Journal articles on the topic 'Cantor alloy'
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Glatzel, Uwe, Felix Schleifer, Christian Gadelmeier, Fabian Krieg, Moritz Müller, Mike Mosbacher, and Rainer Völkl. "Quantification of Solid Solution Strengthening and Internal Stresses through Creep Testing of Ni-Containing Single Crystals at 980 °C." Metals 11, no. 7 (July 16, 2021): 1130. http://dx.doi.org/10.3390/met11071130.
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Various alloy compositions were cast as single crystals in a Bridgman vacuum induction furnace and creep tested at 980 °C: pure Ni, the equiatomic alloys CoCrNi and CrMnFeCoNi (Cantor alloy), single-phase fcc (Ni) solid solution alloys (with the composition of the matrix-phase of CMSX-3 and CMSX-4), and two-phase Ni-based superalloys CMSX-3 and CMSX-4. Due to the single-crystal state, grain size effects, grain boundary sliding, and grain boundary diffusion can be excluded. The results identify two major strengthening mechanisms: solid solution strengthening and other mechanisms summarized as precipitation hardening. Configurational entropy does not increase creep strength: The Cantor alloy, with the highest configurational entropy of all alloys tested, shows a weak and similar creep strength at 980 °C in comparison to pure Ni with zero configurational entropy. The element Re is a very effective strengthener, both in single-phase fcc (Ni) solid solution alloys as well as in two-phase superalloys. Quantitative estimations of different strengthening mechanisms: internal back stress, misfit stresses, Orowan bowing, and γ′-phase cutting (in the case of two-phase superalloys) are presented. Finite element simulations allow estimating the influence of solid solution strengthening of the matrix on the creep behavior of the two-phase superalloys.
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Zhang, Xiangkai, Hanting Ye, Jacob C. Huang, Taiyou Liu, Pinhung Lin, Yaocheng Wu, Mintsang Tsai, Yuchin Liao, and Jason S. C. Jang. "Nano-Scaled Creep Response of TiAlV Low Density Medium Entropy Alloy at Elevated Temperatures." Materials 13, no. 1 (December 20, 2019): 36. http://dx.doi.org/10.3390/ma13010036.
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A low density, medium entropy alloy (LD-MEA) Ti33Al33V34 (4.44 g/cm3) was successfully developed. The microstructure was found to be composed of a disordered body-centered-cubic (BCC) matrix and minor ordered B2 precipitates based on transmission electron microscopy characterization. Equilibrium and non-equilibrium modeling, simulated using the Calphad approach, were applied to predict the phase constituent. Creep behavior of {110} grains at elevated temperatures was investigated by nanoindentation and the results were compared with Cantor alloy and Ti-6Al-4V alloy. Dislocation creep was found to be the dominant mechanism. The decreasing trend of hardness in {110} grains of BCC TiAlV is different from that in {111} grains of face-centered-cubic (FCC) Cantor alloy due to the different temperature-dependence of Peierls stress in these two lattice structures. The activation energy value of {110} grains was lower than that of {111} grains in FCC Cantor alloy because of the denser atomic stacking in FCC alloys. Compared with conventional Ti-6Al-4V alloy, TiAlV possesses considerably higher hardness and specific strength (63% higher), 83% lower creep displacement at room temperature, and 50% lower creep strain rate over the temperature range from 500 to 600 °C under the similar 1150 MPa stress, indicating a promising substitution for Ti-6Al-4V alloy as structural materials.
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Yamanaka, Syuki, Ken-ichi Ikeda, and Seiji Miura. "The effect of titanium and silicon addition on phase equilibrium and mechanical properties of CoCrFeMnNi-based high entropy alloy." Journal of Materials Research 36, no. 10 (May 28, 2021): 2056–70. http://dx.doi.org/10.1557/s43578-021-00251-0.
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Abstract The effects of Ti and Si addition on the phase equilibrium and mechanical properties of the equiatomic CoCrFeMnNi high entropy alloy (Cantor alloy) were investigated. The phase equilibrium at 1000 °C was determined from the result of X-ray diffraction and electron probe micro-analysis. Ti addition stabilizes the $$\sigma$$ σ phase, A12 phase and C14-Laves phase, while Si addition stabilizes the A13 phase. The phase relationships were represented by projection onto (Co, Fe, Mn, Ni)–Cr–X(Ti or Si) isothermal ternary cross-section at 1000 °C in Co–Cr–Fe–Mn–Ni–X senary system. Tensile tests were conducted on Cantor-based fcc single solid solution alloys with Ti or Si dissolution at room temperature. The 0.2% yield strength and ultimate tensile strength increased with either element addition. The Ti-added alloy showed higher strength than the Si-added alloy. The difference in ductility in the alloys is related to their strain hardening behavior in the higher strain range. Graphic abstract
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Babić, Emil, Đuro Drobac, Ignacio Alejandro Figueroa, Mathilde Laurent-Brocq, Željko Marohnić, Vesna Mikšić Trontl, Damir Pajić, et al. "Transition from High-Entropy to Conventional Alloys: Which Are Better?" Materials 14, no. 19 (October 5, 2021): 5824. http://dx.doi.org/10.3390/ma14195824.
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The study of the transition from high-entropy alloys (HEAs) to conventional alloys (CAs) composed of the same alloying components is apparently important, both for understanding the formation of HEAs and for proper evaluation of their potential with respect to that of the corresponding CAs. However, this transition has thus far been studied in only two types of alloy systems: crystalline alloys of iron group metals (such as the Cantor alloy and its derivatives) and both amorphous (a-) and crystalline alloys, TE-TL, of early (TE = Ti, Zr, Nb, Hf) and late (TL = Co, Ni, Cu) transition metals. Here, we briefly overview the main results for the transition from HEAs to CAs in these alloy systems and then present new results for the electronic structure (ES), studied with photoemission spectroscopy and specific heat, atomic structure, thermal, magnetic and mechanical properties of a-TE-TL and Cantor-type alloys. A change in the properties of the alloys studied on crossing from the HEA to the CA concentration range mirrors that in the ES. The compositions of the alloys having the best properties depend on the alloy system and the property selected. This emphasizes the importance of knowing the ES for the design of new compositional complex alloys with the desired properties.
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Campari, Enrico Gianfranco, Angelo Casagrande, Elena Colombini, Magdalena Lassinantti Gualtieri, and Paolo Veronesi. "The Effect of Zr Addition on Melting Temperature, Microstructure, Recrystallization and Mechanical Properties of a Cantor High Entropy Alloy." Materials 14, no. 20 (October 12, 2021): 5994. http://dx.doi.org/10.3390/ma14205994.
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The effect of Zr addition on the melting temperature of the CoCrFeMnNi High Entropy Alloy (HEA), known as the “Cantor’s Alloy”, is investigated, together with its micro-structure, mechanical properties and thermomechanical recrystallization process. The base and Zr-modified alloys are obtained by vacuum induction melting of mechanically pre-alloyed powders. Raw materials are then cold rolled and annealed. recrystallization occurred during the heat treatment of the cold-rolled HEA. The alloys are characterized by X-ray diffraction, electron microscopy, thermal analyses, mechanical spectroscopy and indentation measures. The main advantages of Zr addition are: (1) a fast vacuum induction melting process; (2) the lower melting temperature, due to Zr eutectics formation with all the Cantor’s alloy elements; (3) the good chemical alloy homogeneity; and (4) the mechanical properties improvement of re-crystallized grains with a coherent structure. The crystallographic lattice of both alloys results in FCC. The Zr-modified HEA presents a higher recrystallization temperature and smaller grain size after recrystallization with respect to the Cantor’s alloy, with precipitation of a coherent second phase, which enhances the alloy hardness and strength.
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Ledieu, J., M. Feuerbacher, C. Thomas, M. C. de Weerd, S. Šturm, M. Podlogar, J. Ghanbaja, S. Migot, M. Sicot, and V. Fournée. "The (110) and (320) surfaces of a Cantor alloy." Acta Materialia 209 (May 2021): 116790. http://dx.doi.org/10.1016/j.actamat.2021.116790.
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Gromov, V. E., Yu A. Rubannikova, S. V. Konovalov, K. A. Osintsev, and S. V. Vorob’ev. "Generation of increased mechanical properties of Cantor highentropy alloy." Izvestiya. Ferrous Metallurgy 64, no. 8 (September 2, 2021): 599–605. http://dx.doi.org/10.17073/0368-0797-2021-8-599-605.
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The article considers a brief review of the last years of Russian and foreign research on the possibilities of improving mechanical properties of the Cantor quinary highentropy alloy (HEA) with different phase composition in wide temperature range. The alloy, one of the frst created equimolar HEAs with FCC structure, needs mechanical properties improvement in accordance with possible felds of application in spite of its high impact toughness and increased creep resistance. It has been noted that bimodal distribution of the grains by sizes under severe plastic torsional strain at high pressure of 7.8 GPa of cast alloy and subsequent shorttime annealing at 873 and 973 K can change strength and plastic properties. Nanodimensional scale of the grains surrounded by amorphous envelope has been obtained for HEA produced by the method of magnetron sputtering and subsequent annealing at 573 K. In such a twophase alloy nanohardness amounted to 9.44 GPa and elasticity modulus – to 183 GPa. Using plasticity effect induced by phase transformation in (CrMnFeCoNi)50Fe50 alloy obtained by the method of laser additive technology the ultimate strength of 415 – 470 MPa has been reached at high level of plasticity up to 77 %. It has been ensured by FCC → BCC diffusionless transformation. It is shown that difference in mechanisms of plastic strain of cast alloy at 77 K and 293 K (dislocation glide and twinning) determines a combination of increased “strengthplasticity” properties. Samples for generation of twins prestrained at 77 K exhibit increased strength and plasticity under subsequent loading at 293 K in comparison with the unstrained ones. For HEA obtained by laser additive technology this way of increasing properties is also true. The way of improving mechanical properties at the expense of electron beam processing is noted. The attention is paid to the necessity of taking into account the role of entropy, crystal lattice distortions, shortrange order, weak diffusion and “cocktail” effect in the analysis of mechanical properties.
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Kang, You Bin, Seung Min Oh, Kap Ho Lee, and Sun Ig Hong. "Stress-Strain Responses of Multi-Phase CoCrCuMnNi and CoCrMnFeCu Alloys." Key Engineering Materials 765 (March 2018): 166–72. http://dx.doi.org/10.4028/www.scientific.net/kem.765.166.
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Stress-strain responses and microstructure of multi-phase CoCrCuMnNi and CoCrMnFeCu alloys in which Fe or Ni was replaced by Cu from Cantor alloy were studied. The deformation mechanisms of CoCrCuMnNi and CoCrMnFeCu were observed to be influenced by the presence of brittle sigma phase and the separated Cu-rich and the matrix phase. CoCrCuMnNi exhibited the relatively lower strength and excellent deformability, while CrMnFeCoCu alloy exhibited higher strength and lower ductility. The higher strength and the lower ductility of CoCrCuMnNi is associated with the presence more frequent and coarser sigma phase than those in CoCrCuMnNi.
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Brotzu, Andrea, Stefano Natali, Zortea Laura, and De Filippo Barbara. "High Entropy Cantor Alloys (HEAs) modification induced by tungsten alligation, heat treatment and deep cold plastic deformation." Frattura ed Integrità Strutturale 17, no. 63 (December 21, 2022): 309–20. http://dx.doi.org/10.3221/igf-esis.63.24.
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High Entropy Alloys (HEAs) is a unique class of materials that combine particular properties in a large-scale of temperatures, able to guarantee new unexplored materials and alloys with several potentially engineering applications (i.e. space and aerospace industries). As promising structural materials, HEAs consist of five or more principal elements. As a consequence of the monophasic microstructure which usually characterizes HEAs, these alloys offer an excellent combination of strength, strain hardening ability, good plasticity, ductility and fracture toughness especially at cryogenic temperatures better than the existing conventional metals and alloys. For the above reasons, the present work deals with Classic Cantor alloy, a well-known CoCrFeMnNi HEA, where mechanical properties were improved using low cost casting techniques and a combination of different metallurgical methodologies (heat treatment, cold working and adding alloying elements). A promising alloy element, tungsten, was used in the experimentation where mechanical and microstructural characterization were performed using different techniques
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Ko, Jun Yeong, and Sun Ig Hong. "Effect of Carbon Addition on the Cast and Rolled Microstructures of FeCoCrNiMn High Entropy Alloys." Key Engineering Materials 737 (June 2017): 16–20. http://dx.doi.org/10.4028/www.scientific.net/kem.737.16.
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In this study, the effect of carbon addition the cast and rolled microstructures of Cantor alloy type FeCoCrNiMn high entropy alloys. Both as-cast FeCoCrNiMn and FeCoCrNiMnC0.1 alloys have dendritic microstructure. Small particles, which may be associated carbon addition exist in the dendrite arms in FeCoCrNiMnC0.1 alloy. After homogenization treatment at 1327K for 24 hrs., dendritic structure was completely eliminated after annealing. Dendritic structure was converted to the structure with elongated grains, especially for carbon added FeCoCrNiMnC0.1. The development of elongated grains is associated with the direction of the primary arms in the dendritic structure. Carbides are segregated at the grain boundaries in FeCoCrNiMnC0.1 alloy. It also appears that growth of grains is impeded by the segregation of carbides. It is apparent that the grain boundary precipitates are Cr-rich. Both the strength and ductility of FeCoCrNiMnC0.1 increased over FeCoCrNiMn with the addition of 0.1 wt. % carbon. The increase of ductility in FeCoCrNiMnC0.1 may be caused by the rapid hardening in FeCoCrNiMnC0.1 due to dislocation-solute interaction.
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Wang, Hao, Dengke Chen, Xianghai An, Yin Zhang, Shijie Sun, Yanzhong Tian, Zhefeng Zhang, et al. "Deformation-induced crystalline-to-amorphous phase transformation in a CrMnFeCoNi high-entropy alloy." Science Advances 7, no. 14 (March 2021): eabe3105. http://dx.doi.org/10.1126/sciadv.abe3105.
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The Cantor high-entropy alloy (HEA) of CrMnFeCoNi is a solid solution with a face-centered cubic structure. While plastic deformation in this alloy is usually dominated by dislocation slip and deformation twinning, our in situ straining transmission electron microscopy (TEM) experiments reveal a crystalline-to-amorphous phase transformation in an ultrafine-grained Cantor alloy. We find that the crack-tip structural evolution involves a sequence of formation of the crystalline, lamellar, spotted, and amorphous patterns, which represent different proportions and organizations of the crystalline and amorphous phases. Such solid-state amorphization stems from both the high lattice friction and high grain boundary resistance to dislocation glide in ultrafine-grained microstructures. The resulting increase of crack-tip dislocation densities promotes the buildup of high stresses for triggering the crystalline-to-amorphous transformation. We also observe the formation of amorphous nanobridges in the crack wake. These amorphization processes dissipate strain energies, thereby providing effective toughening mechanisms for HEAs.
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Chida, Yoshihiro, Takeru Tomimori, Tomoaki Ebata, Noboru Taguchi, Tsutomu Ioroi, Naoto Todoroki, and Toshimasa Wadayama. "Oxygen Reduction Reaction of Pt and Non-PGM Transition Metal High Entropy Alloys Single Crystal Stacking Structures." ECS Meeting Abstracts MA2022-02, no. 42 (October 9, 2022): 1552. http://dx.doi.org/10.1149/ma2022-02421552mtgabs.
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Introduction Nanoparticles of Pt as well as Pt-based alloys are widely used as cathode catalyst materials for proton exchange membrane fuel cells (PEMFC). However, electrochemical stability of the materials is rather low under practical operating conditions of PEMFC cathode, resulting in severe deactivation of oxygen reduction reaction (ORR). Therefore, further material’s developments are required for next-generation PEMFC cathode catalysts, i.e., more enhanced ORR durability with low platinum group metal (PGM) usage. High entropy alloys (HEAs), defined as single phase solid solutions of five or more elements in equal composition ratios, are known as thermodynamically stable, in comparison to conventional binary alloys. Furthermore, complex atomic-level local structures bring about unique electronic as well as (electro-)chemical properties that originating from lattice strains induced by specific local structures and/or so-called sluggish diffusion of the constituent elements. [1] However, to our best knowledge, no study has been made for ORR properties of Pt alloying with non-PGM Cantor alloy (fcc structure HEA with equi-atomic ratio of Cr-Mn-Fe-Co-Ni [2]) elements in strong acid condition. In this study, we synthesized lattice stacking structures of Pt/HEA(hkl) (hkl = (111), (110), (100)) through arc-plasma deposition (APD) of the Cantor alloy layer on Pt(hkl) substrate surfaces, followed by deposition of the surface Pt layer in ~10-7 Pa. Then, we performed cross-sectional STEM-EDS observations for Pt/HEA/Pt(hkl) stacking structures with atomic-level resolution and evaluated the ORR properties (initial activity and structural stability). Experimental An APD target of Cr-Mn-Fe-Co-Ni (Cantor alloy) was fabricated by sintering of equal quantity corresponding elements. 10 ML(monolayer)-thick (1 ML = ca. 0.3 nm) Cantor alloy layer (as HEA) was vacuum-deposited by APD on surface cleaned Pt(hkl) substrate surfaces at 300 K, and subsequently annealed in vacuum at 773 K for 30 minutes. Then, 4ML-thick Pt layer was deposited on the pre-deposited Cantor alloy layer at 300 K and annealed at 623 K. The samples thus prepared are designated as Pt/HEA/Pt(hkl). The atomic-level micro-structures and chemical bonding states of Pt/HEA/Pt(hkl) surfaces were characterized by cross-sectional STEM-EDS, RHEED, XPS etc. CV and LSV with the RDE method were conducted in N2-purged and O2-saturated 0.1 M HClO4. ORR activity was evaluated from j k values at 0.9 V vs. RHE by using Koutecky-Levich equation and structural stability (ORR durability) was discussed based upon activity transitions during applying the potential cycles (PCs) of 0.6(3s)‐1.0(3s) V vs. RHE in O2 saturated 0.1 M HClO4 at room temperature. Results and Discussion Atomically-resolved, cross-sectional HAADF-STEM images for Pt/HEA/Pt(hkl) (a) and EDS line profiles of elemental distributions at corresponding yellow arrows (b) are presented in Figure 1. As clearly shown in (a), irrespective of the Pt surface indices, (hkl), HEA (Cantor alloy) and surface Pt layers are epitaxially grown on the substrates. By contrast, elemental distributions in each surface normal (b) seriously depend on the substrate Pt lattice indices. Notably, severe thermal diffusion of the constituent elements including Pt is confirmed by (a) and (b) for both Pt/HEA/Pt(110) and (100). Figure 2 summarizes electrochemical results. 4ML-thick-Pt/10ML-thick-Co/Pt(hkl) that prepared under the same preparation condition of Pt/HEA/Pt(hkl), and clean Pt(hkl) (light blue and gray, respectively) are also shown as references. As shown in the figure, the Pt/HEA and Pt/Co fabricated on Pt(111) substrate (top) show quite similar CV characteristics (shrink in hydrogen adsorption charges (0 – 0.3 V) and higher potential shifts in oxygen-related species adsorption (0.6 – 1.0 V)), in comparison to clean Pt(111), and almost the same initial ORR activity. Meanwhile, the Pt/HEA fabricated on Pt(110) and (100) substrates show more reduced hydrogen absorption charges, compared with corresponding Pt/Co samples. Particularly, distinctive redox features for clean Pt(110) at 0.12 V and for Pt(100) at 0.35 V are absent for corresponding CVs, suggesting specific topmost surface atomic-structures might be formed in the electrolyte, that probably resulting from significant electronic interactions between surface Pt and HEA constituent elements (Cr, Mn, Fe, Co, Ni) and/or local strain of the surface Pt layer induced by distorted Pt-HEA lattices located nearby. One might notice that Pt/HEA/Pt(110) reveals remarkable ORR activity enhancement compared with corresponding Pt/Co/Pt(110), while the activities for Pt/HEA and corresponding Pt/Co surfaces fabricated on Pt(100) are almost the same value. At the meeting, correlations between surface atomic-level micro-structures of Pt/HEA/Pt(hkl) and ORR properties will be discussed in detail. Acknowledgement This study was supported by new energy and industrial technology development organization (NEDO) of Japan and JST SPRING, Grant Number JPMJJSP2114. Reference [1] J. Yeh, JOM, 65, 1759 (2013). [2] B. Cantor et al., Mater. Sci. Eng. A, 375, 213 (2004). Figure 1
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Gromov, V. E., S. V. Konovalov, Yu A. Shlyarova, M. O. Efimov, and I. A. Panchenko. "Control of mechanical properties of a high-entropy alloy Cantor CoCrFeMnNi." Izvestiya. Ferrous Metallurgy 65, no. 8 (September 1, 2022): 563–72. http://dx.doi.org/10.17073/0368-0797-2022-8-563-572.
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A brief analysis of the work on changing the mechanical properties of the high-energy alloy (HEA) Cantor CoCrFeMnNi in various ways has been performed. The article describes the influence of alloying with aluminum, vanadium, manganese, titanium, silicon, carbon, copper on the hardening of wind turbines obtained by vacuum arc melting, laser melting, arc melting and drip casting, mechanical alloying with subsequent plasma sintering, gas sputtering followed by shock wave and static compaction. It is shown that additives of 2.5 % TiC and 5 % WC significantly improve the tensile strength, but reduce the elongation to failure. The effect of grain size in the range of 4.4 – 155 µm is to increase the tensile strength with a decrease in grain size. Lowering the temperature increases the strength and yield limits for grains of all sizes. Intensive plastic deformation forming nanoscale (~50 nm) grains significantly increases the tensile strength up to 1950 MPa and hardness up to 520 HV. Subsequent isochronous and isothermal annealing allows varying the strength and ductility of wind turbines. The formation of nanostructured-phase states during shock compounding, mechanical alloying and subsequent spark plasma formation significantly increase the tensile strength at room temperature, maintaining excellent plasticity (elongation of approximately 28 %). As one of the methods of modifying the mechanical properties of wind turbines, the authors propose electron-beam processing (EPO). The analysis of the deformation curves of the wind turbine, obtained by the technology of wire-arc additive production, after EPO with an electron beam energy density of 10 – 30 J/cm2, has been carried out; assumptions about the reasons for the decrease in strength and ductility characteristics have been found and substantiated. A comparative analysis of mechanical properties of the Cantor wind turbine obtained by various methods was carried out, and the reasons for discrepancy in the values of strength and plastic parameters were noted.
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Panchenko, Marina, Evgenii Melnikov, Darya Gurtova, and Elena Astafurova. "Effect of carbon alloying on hydrogen embrittlement of a Cantor alloy." Letters on Materials 12, no. 4 (December 2022): 282–86. http://dx.doi.org/10.22226/2410-3535-2022-4-282-286.
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Gianelle, Madison A., Chase Clapp, Animesh Kundu, and Helen M. Chan. "Solid state processing of the cantor derived alloy CoCrFeMnNi by oxide reduction." Results in Materials 14 (June 2022): 100286. http://dx.doi.org/10.1016/j.rinma.2022.100286.
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Oh, Seung Min, and Sun Ig Hong. "Microstructure and Mechanical Properties of Equitomic CoCrFeCuNi High Entropy Alloy." Key Engineering Materials 765 (March 2018): 149–54. http://dx.doi.org/10.4028/www.scientific.net/kem.765.149.
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Microstructure and mechanical properties of cast and cold-rolled equitomic CoCrFeCuNi alloy in which Mn was substituted by Cu from Cantor alloy was studied. The separation into two solid solutions (Cr-Co-Fe rich and Cu-rich phases) were observed in CoCrFeCuNi. Coarsening and widening of interdendritic Cu-rich phase after homogenization was observed after homogenization, suggesting Cu-rich phase is thermodynamically stable. The compressive stress-strain curves of homogenized cast CoCrFeCuNi alloy exhibited the reasonably high strength and excellent deformability for the cast alloy. The yield strength increased up to 960MPa after cold rolling from 265MPa of the homogenized cast alloy. The significant increase of yield strength is thought to be associated with the alignment of Cu-rich second phase in addition to cold work dislocation storage after cold rolling.
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Haase, Christian, and Luis Antonio Barrales-Mora. "From High-Manganese Steels to Advanced High-Entropy Alloys." Metals 9, no. 7 (June 27, 2019): 726. http://dx.doi.org/10.3390/met9070726.
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Arguably, steels are the most important structural material, even to this day. Numerous design concepts have been developed to create and/or tailor new steels suited to the most varied applications. High-manganese steels (HMnS) stand out for their excellent mechanical properties and their capacity to make use of a variety of physical mechanisms to tailor their microstructure, and thus their properties. With this in mind, in this contribution, we explore the possibility of extending the alloy design concepts that haven been used successfully in HMnS to the recently introduced high-entropy alloys (HEA). To this aim, one HMnS steel and the classical HEA Cantor alloy were subjected to cold rolling and heat treatment. The evolution of the microstructure and texture during the processing of the alloys and the resulting properties were characterized and studied. Based on these results, the physical mechanisms active in the investigated HMnS and HEA were identified and discussed. The results evidenced a substantial transferability of the design concepts and more importantly, they hint at a larger potential for microstructure and property tailoring in the HEA.
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Čech, Jaroslav, Petr Haušild, Miroslav Karlík, Jiří Čapek, and Filip Průša. "Indentation Size Effect in CoCrFeMnNi HEA Prepared by Various Techniques." Materials 14, no. 23 (November 27, 2021): 7246. http://dx.doi.org/10.3390/ma14237246.
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High entropy alloys (HEAs) are materials of great application potential and which have been extensively studied during the last two decades. As the number of possible element combinations is enormous, model materials representing certain groups of HEAs are used for the description of microstructure, properties, and deformation mechanisms. In this study, the microstructure and mechanical properties of the so-called Cantor alloy composed of Co, Cr, Fe, Mn, and Ni in equiatomic ratios prepared by various techniques (casting, melt-spinning, spark plasma sintering) were examined. The research focused on the indentation measurements, namely, the indentation size effect describing the evolution of the hardness with penetration depth. It was found that the standard Nix–Gao model can be used for this type of alloy at higher penetration depths and its parameters correlate well with microstructural observations. The Nix–Gao model deviates from the measured data at the submicrometer range and the applied modification affords additional information on the deformation mechanism.
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Balyakin, I. A., and A. A. Rempel. "Atomistic Calculation of the Melting Point of the High-Entropy Cantor Alloy CoCrFeMnNi." Doklady Physical Chemistry 502, no. 1 (January 2022): 11–17. http://dx.doi.org/10.1134/s0012501622010018.
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Akinbami, Olusola, Lesego M. Mohlala, Desmond Klenam, Josias van der Merwe, and Michael Bodunrin. "The Status of High Entropy Alloys Studies in Africa: An Overview." Key Engineering Materials 917 (April 13, 2022): 41–53. http://dx.doi.org/10.4028/p-yu1c05.
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One valid way to access the state of knowledge in a specific research area is by assessing the availability of quality publications in that research area. In this work, we assess the level of high entropy research in Africa considering that it is a hot topic in the field of materials engineering. Precedent on the independent studies of Cantor and Yeh, the conventional alloying techniques are evolving towards the high entropy approach. To determine the extent of high entropy research in Africa, SCOPUS database was used following specific keywords searches. The result ranked South Africa as the most publisher of high entropy alloy-related articles in Africa followed by Egypt then Kenya, Nigeria and Algeria. Notably, most high entropy alloy articles published from South Africa and Egypt are within the last two years. In South Africa, the high entropy alloys are majorly fabricated via arc melting, spark plasma sintering and laser deposition techniques while Egypt shows proficiency in studies focusing on mechanical alloying, sintering and casting processes for high entropy alloys. Conclusively, the research output from Africa is still lagging when compared to those of other continents however, maximizing the limited infrastructure within Africa and improving collaborations will go a long way towards improving Africa’s research output on high entropy alloys.
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Yoon, Kook Noh, Hyun Seok Oh, Je In Lee, and Eun Soo Park. "Development of Light-Weight TRIP/TWIP FCC High Entropy Alloy with High Specific Strength and Large Ductility." Korean Journal of Metals and Materials 59, no. 12 (December 5, 2021): 857–69. http://dx.doi.org/10.3365/kjmm.2021.59.12.857.
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In this study we developed a novel (TRIP+TWIP) high entropy alloy (HEA) with high specific strength and large ductility. First, by controlling the atomic constitution of the 3d transition metals (Cr, Mn, Fe, Co, and Ni), we designed a light-weight TRIP-assisted dual-phase HEA with a non-equiatomic composition of Cr22Mn6Fe40Co26Ni6, which exhibited 5% lighter density than the Cantor HEA. Secondly, we systematically added Al (a lightweight element (2.7 g/cm3), which has a large atomic size misfit with 3d transition metals, and Ferrite stabilizer) up to 5 at.% in Cr22Mn6Fe40Co26Ni6 HEA. With increasing Al content, the phase constitution of the alloy changed from a dual-phase of FCC and HCP (0 to 2.0 at.%) to a FCC single-phase (2.5 to 3.5 at.%), to a dual-phase of FCC and BCC (4.0 to 5.0 at.%). In particular, the (Cr22Mn6Fe40Co26Ni6)97.5Al2.5 HEA with the FCC single-phase exhibited a large Hall-Petch coefficient and relatively lower thermal conductivity due to its three times larger atomic size mismatch (δ) than the Cantor HEA, which causes the superior solid solution strengthening effect. Furthermore, the (Cr22Mn6Fe40Co26Ni6)96Al4.0 HEA, a boundary composition of BCC precipitation in the FCC phase, exhibited a 10% higher specific strength than the Cantor HEA as well as 50% larger strain, due to the unique TRIP and TWIP complex deformation mechanism. This result shows that the addition of Al in Cr22Mn6Fe40Co26Ni6 HEA can result not only in greater chemical complexity due to the multicomponent high entropy compositions, but also microstructural complexity due to the increase in competing crystalline phases. The confusion effect caused by both complexities lets the alloy overcome the trade-off relationship among conflicting intrinsic properties, such as strength versus ductility (or density). Consequently, these results pave the way for a new design strategy of a novel (TRIP+TWIP) HEA with high specific strength and large ductility.
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Li, Y. J., A. Savan, and A. Ludwig. "Atomic scale understanding of phase stability and decomposition of a nanocrystalline CrMnFeCoNi Cantor alloy." Applied Physics Letters 119, no. 20 (November 15, 2021): 201910. http://dx.doi.org/10.1063/5.0069107.
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Lobzenko, Ivan, Daixiu Wei, Mitsuhiro Itakura, Yoshinori Shiihara, and Tomohito Tsuru. "Improved mechanical properties of Co-free high-entropy Cantor alloy: A first-principles study." Results in Materials 17 (March 2023): 100364. http://dx.doi.org/10.1016/j.rinma.2023.100364.
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Oh, Seung Min, and Sun Ig Hong. "Microstructure and Mechanical Properties of Equiatomic CrMnCoNiCu High Entropy Alloy." Materials Science Forum 909 (November 2017): 39–43. http://dx.doi.org/10.4028/www.scientific.net/msf.909.39.
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Microstructure and mechanical properties of equiatomic CrMnCoNiCu alloy in which Fe was substituted by Cu from Cantor alloy was studied. The separation of solid solution phase into two solid solutions (Cr-Co rich and Cu-rich phases) were observed in CrMnCoNiCu. The coarsening and widening of interdendritic Cu-rich phase after homogenization was observed and supported by the increase of XRD peak height from Cu-rich phase compared to that from Cr-Co rich phase after homogenization. The increase of the peak from Cu-rich phase can be attributed to the thermodynamic stability of Cu due to positive mixing enthalpy of adding Cu. The stress-strain curves of CrMnCoNiCu alloy exhibited the reasonably high strength and excellent deformability for the cast alloy. The yield stress of CrMnCoNiCu was observed to be 390MPa and it could be deformed without crack formation up to the true strain 0.85 to reach the flow stress as high as 662Mpa.
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Keil, Tom, Daniel Utt, Enrico Bruder, Alexander Stukowski, Karsten Albe, and Karsten Durst. "Solid solution hardening in CrMnFeCoNi-based high entropy alloy systems studied by a combinatorial approach." Journal of Materials Research 36, no. 12 (April 21, 2021): 2558–70. http://dx.doi.org/10.1557/s43578-021-00205-6.
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Abstract Solid solution hardening in high entropy alloys was studied for the Cantor alloy using diffusion couples and nanoindentation. We study a continuous variation of the alloying content and directly correlate the nanoindentation hardness to the local composition up to the phase boundary. The composition dependent hardness is analysed using the Labusch model and the more recent Varvenne model. The Labusch model has been fitted to experimental data and confirms Cr as the most potent strengthening element. For comparison of the experimental hardness and the predicted yield strength of the Varvenne model, a concentration-dependent strain-hardening factor is introduced to account for strain hardening during indentation, which leads to a very good agreement between experiment and model. A study of the input parameters of the Varvenne model, performed by atomistic computer simulations, shows no significant effect of fluctuations in the atomic size misfit volumes or in the local shear modulus to the computed yield strength. Graphic Abstract
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Oh, Seung Min, and Sun Ig Hong. "Microstructural Evolution and Mechanical Properties in a Mn1.05Fe1.05CoNiCu0.9 High Entropy Alloy." Key Engineering Materials 737 (June 2017): 44–49. http://dx.doi.org/10.4028/www.scientific.net/kem.737.44.
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In the present study, the microstructural stability and mechanical properties of a MnFeCoNiCu alloy in which Cr was replaced by Cu from Cantor composition (CoCrFeMnNi) was studied. In the as-cast alloy, the dendrite arms are enriched with Cu and Mn and matrix between dendrite arms is enriched with Fe and Co. Ni was richer in the matrix, but also observed in the dendrite arms. Cu and Mn tend to segregate and solidify initially because the melting temperatures of Cu and Mn are lower than Fe and Co, resulting in the growth of Cu-Mn dendrite. After homogenization, the dendrites structure disappeared and grain boundaries are visible, indicating the segregated elements in the dendrite structure were homogenized. The presence of single phase FCC structure was confirmed after homogenization. The tensile strength of 1220 MPa with the ductility of 6 % was obtained in MnFeCoNiCu alloy.
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Ehler, Andrew, Abhijeet Dhiman, Tyler Dillard, Remi Dingreville, Erin Barrick, Andrew Kustas, and Vikas Tomar. "High-Strain Rate Spall Strength Measurement for CoCrFeMnNi High-Entropy Alloy." Metals 12, no. 9 (September 7, 2022): 1482. http://dx.doi.org/10.3390/met12091482.
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In this study, we experimentally investigate the high stain rate and spall behavior of Cantor high-entropy alloy (HEA), CoCrFeMnNi. First, the Hugoniot equations of state (EOS) for the samples are determined using laser-driven CoCrFeMnNi flyers launched into known Lithium Fluoride (LiF) windows. Photon Doppler Velocimetry (PDV) recordings of the velocity profiles find the EOS coefficients using an impedance mismatch technique. Following this set of measurements, laser-driven aluminum flyer plates are accelerated to velocities of 0.5–1.0 km/s using a high-energy pulse laser. Upon impact with CoCrFeMnNi samples, the shock response is found through PDV measurements of the free surface velocities. From this second set of measurements, the spall strength of the alloy is found for pressures up to 5 GPa and strain rates in excess of 106 s−1. Further analysis of the failure mechanisms behind the spallation is conducted using fractography revealing the occurrence of ductile fracture at voids presumed to be caused by chromium oxide deposits created during the manufacturing process.
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Fan, Pengfei, Nirmal Kumar Katiyar, Xiaowang Zhou, and Saurav Goel. "Uniaxial pulling and nano-scratching of a newly synthesized high entropy alloy." APL Materials 10, no. 11 (November 1, 2022): 111118. http://dx.doi.org/10.1063/5.0128135.
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Multicomponent alloys possessing nanocrystalline structure, often alluded to as Cantor alloys or high entropy alloys (HEAs), continue to attract the great attention of the research community. It has been suggested that about 64 elements in the periodic table can be mixed in various compositions to synthesize as many as ∼108 different types of HEA alloys. Nanomechanics of HEAs combining experimental and atomic simulations are rather scarce in the literature, which was a major motivation behind this work. In this spirit, a novel high-entropy alloy (Ni25Cu18.75Fe25Co25Al6.25) was synthesized using the arc melting method, which followed a joint simulation and experimental effort to investigate dislocation-mediated plastic mechanisms leading to side flow, pileup, and crystal defects formed in the sub-surface of the HEA during and after the scratch process. The major types of crystal defects associated with the plastic deformation of the crystalline face-centered cubic structure of HEA were 2,3,4-hcp layered such as defect coordination structures, coherent ∑3 twin boundary, and ∑11 fault or tilt boundary, in combination with Stair rods, Hirth locks, Frank partials, and Lomer–Cottrell locks. Moreover, 1/6 <112> Shockley, with exceptionally larger dislocation loops, was seen to be the transporter of stacking faults deeper into the substrate than the location of the applied cutting load. The (100) orientation showed the highest value for the kinetic coefficient of friction but the least amount of cutting stress and cutting temperature during HEA deformation, suggesting that this orientation is better than the other orientations for improved contact-mode manufacturing.
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Ji, Weiming, and Mao See Wu. "Atomistic studies of ductile fracture of a single crystalline cantor alloy containing a crack at cryogenic temperatures." Engineering Fracture Mechanics 258 (December 2021): 108120. http://dx.doi.org/10.1016/j.engfracmech.2021.108120.
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Wang, H., ZG Zhu, HS Chen, SM Nai, XH An, RK Zheng, S. Primig, SP Ringer, and XZ Liao. "Effect of Cyclic Thermal Loadings on the Microstructural Evolution of a Cantor Alloy in 3D Printing Processes." Microscopy and Microanalysis 25, S2 (August 2019): 2568–69. http://dx.doi.org/10.1017/s1431927619013576.
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Chen, Wentian, Yufan Wu, Lin Guo, Ji Gu, Junyang He, and Min Song. "Dual-effects of carbon doping on the recrystallization kinetics of the Cantor alloy during mid-temperature annealing." Intermetallics 155 (April 2023): 107828. http://dx.doi.org/10.1016/j.intermet.2023.107828.
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Zhang, Guoying, Qi Zhang, Qikai Li, Yuan Wu, Chuanyi Ji, and Mo Li. "Homogenization of diffusion in multicomponent liquids." Journal of Chemical Physics 157, no. 24 (December 28, 2022): 244503. http://dx.doi.org/10.1063/5.0130697.
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Diffusion is a key kinetic factor determining chemical mixing and phase formation in liquids. In multicomponent systems, the presence of different elements makes it experimentally challenging to measure diffusivities and understand their mechanisms. Using a molecular dynamics simulation, we obtain the diffusion constants and the atomic process of a model Cantor alloy liquid made of five equimolar components. We show that the diffusivities conform remarkably well to the Arrhenius law in a wide range of temperature covering both the equilibrium and undercooled liquid regions. The activation energies for all the alloy elements with different bonding energies and atomic sizes are close to each other. The results suggest that the diffusivity in the multicomponent liquid tends to be homogenized by the components with marginal differences. This finding allows us to treat the different elements as a single type of atom, the pseudo-atom, for diffusional and maybe structural and physical properties in multicomponent liquids.
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Sharma, Ashutosh, Min Chul Oh, and Byungmin Ahn. "Microstructural evolution and mechanical properties of non-Cantor AlCuSiZnFe lightweight high entropy alloy processed by advanced powder metallurgy." Materials Science and Engineering: A 797 (October 2020): 140066. http://dx.doi.org/10.1016/j.msea.2020.140066.
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Yuan, Yuan, Zihao Xu, Piaopiao Han, Zhenhua Dan, Fengxiang Qin, and Hui Chang. "MnO2-decorated metallic framework supercapacitors fabricated from duplex-phase FeCrCoMnNiAl0.75 Cantor high entropy alloy precursors through selective phase dissolution." Journal of Alloys and Compounds 870 (July 2021): 159523. http://dx.doi.org/10.1016/j.jallcom.2021.159523.
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Karantzalis, Alexandros E., Anthoula Poulia, Spyros Kamnis, Athanasios Sfikas, Anastasios Fotsis, and Emmanuel Georgatis. "Modification of Cantor High Entropy Alloy by the Addition of Mo and Nb: Microstructure Evaluation, Nanoindentation-Based Mechanical Properties, and Sliding Wear Response Assessment." Alloys 1, no. 1 (May 10, 2022): 70–92. http://dx.doi.org/10.3390/alloys1010006.
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The classic Cantor (FeCoCrMnNi) isoatomic high entropy alloy was modified by separate additions of Mo and Nb in an effort to optimize its mechanical properties and sliding wear response. It was found that the introduction of Mo and Nb modified the single phase FCC solid solution structure of the original alloy and led to the formation of new phases such as the BCC solid solution, σ-phase, and Laves, along with the possible existence of intermetallic phases. The overall phase formation sequence was approached by parametric model assessment and solidification considerations. Nanoindentation-based mechanical property evaluation showed that due to the introduction of Mo and Nb; the modulus of elasticity and microhardness were increased. Creep nanoindentation assessment revealed the beneficial action of Mo and Nb in increasing the creep resistance based on the stress sensitivity exponent, strain rate sensitivity, and critical volume for the dislocation nucleation considerations. The power law and power law breakdown were identified as the main creep deformation mechanisms. Finally, the sliding wear response was increased by the addition of Mo and Nb with this behavior obeying Archard’s law. A correlation between microstructure, wear track morphologies, and debris characteristics was also attempted.
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Xie, Chenyang, Xuejie Li, Fan Sun, Junsoo HAN, and Kevin Ogle. "The Spontaneous Repassivation of Cr Containing Steels and Multi-Principal Element Alloys." ECS Meeting Abstracts MA2022-02, no. 11 (October 9, 2022): 735. http://dx.doi.org/10.1149/ma2022-0211735mtgabs.
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The corrosion resistance of an alloy in most environments will depend on its ability to spontaneously passivate at the corrosion potential. This is especially true for localized forms of corrosion such as occur in acidic, occluded environments during pitting and crevice corrosion. In the laboratory however, the kinetics of passivation are mainly investigated using electrochemical methods that require polarization of the material via an external power source. Spontaneous passivation cannot directly be observed by this approach. It is therefore of interest to investigate the repassivation phenomena as it occurs at open circuit, driven by the oxidizing agents present in the electrolyte. To this end, we have recently developed a methodology to determine the kinetics of spontaneous passivation using element-resolved electrochemistry (atomic spectroelechemistry, or ASEC) [1-3]. Passivation may be measured by first disrupting the original passive film using an electrochemical perturbation and then monitoring the corrosion rate as a function of time on an element-by-element basis. As the passive film reforms, the corrosion rate decreases allowing a real time monitoring of film formation. The perturbation may be either a cathodic pulse to reduce the passive film as in a conventional polarization curve experiment, or it may be an anodic pulse into the transpassive domain. In addition, the contribution of the individual alloying elements to dissolution and to passive film formation may be quantitatively accessed thereby yielding insight into one of the fundamental questions for engineering new alloys - what is the specific role of the different alloying elements? For example, it is widely recognized that for the Cr containing alloys, Cr is the primary constituent of the passive film, at least when Cr is above about 12%. However, the presence of other elements may affect the efficiency of Cr-oxide film formation, some like Mo in a beneficial way [2], others like Mn in a negative way [3]. Via a simple mass balance, the elemental dissolution rate profiles may be transformed into a time resolved elemental surface enrichment profile. This allows a direct look into the role of the alloying elements. The Figure gives an example of this approach based on the results from Ref. 3. The system under investigation was the high entropy Cantor alloy containing alloyed nitrogen in a sulfuric acid solution. The left-hand side gives the open dissolution rate for an experimental sequence of (a) open circuit, (b) cathodic activation (300 s at -0.8 V vs. SCE), (c) repassivation at open circuit (300 s). Repassivation is indicated by the initially large corrosion rate (active state) followed by the decrease of the corrosion rate as the passive film reforms. The contribution of the individual alloying elements is shown all of which dissolved congruently with the exception of Cr which was below the congruent level (black line) indicative of Cr surface enrichment. The right hand side gives the quantity of Cr enriched on the surface during the sequence calculated by mass balance. Cr dissolves during the cathodic activation but reforms as soon as the potential is released. Also shown is the Cr enrichment during an anodic step to 0.4 V which leads to a more rapid and significant build-up of surface Cr. This presentation will review the methodology of spontaneous passivation measurements for both austenitic stainless steel (304L) and for the high entropy Cantor alloy (equimolar NiFeCrCoMn) with variable Mn content. In particular, we will focus on the differences between repassivation following cathodic activation and transpassive activation. The mechanisms of spontaneous repassivation will be discussed with an emphasis on how the alloying elements influence repassivation under these two conditions. 1) K Ogle “Atomic emission spectroelectrochemistry: real-time rate measurements of dissolution, corrosion, and passivation”, Corrosion 75 (2019)1398-1419. Open access. 2) X Li, J D Henderson, F P Filice, D Zagidulin, M C Biesinger, F Sun, B Qian, D W Shoesmith, J J Noël, K Ogle, “The contribution of Cr and Mo to the passivation of Ni22Cr and Ni22Cr10Mo alloys in sulfuric acid”, Corrosion Science 176, (2020) 109015. 3) X Li, P Zhou, H Feng, Z Jiang, H Li, K Ogle, “Spontaneous passivation of the CoCrFeMnNi high entropy alloy in sulfuric acid solution: The effects of alloyed nitrogen and dissolved oxygen”, Corrosion Science 196(2022)110016. Figure 1
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Oliveros, Daniela, Anna Fraczkiewicz, Antonin Dlouhy, Chen Zhang, Hengxu Song, Stefan Sandfeld, and Marc Legros. "Orientation-related twinning and dislocation glide in a cantor high entropy alloy at room and cryogenic temperature studied by in situ TEM straining." Materials Chemistry and Physics 272 (November 2021): 124955. http://dx.doi.org/10.1016/j.matchemphys.2021.124955.
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Brunke, Florian, Carsten Siemers, and Joachim Rösler. "Second-generation Titanium alloys Ti-15Mo and Ti-13Nb-13Zr: A Comparison of the Mechanical Properties for Implant Applications." MATEC Web of Conferences 321 (2020): 05006. http://dx.doi.org/10.1051/matecconf/202032105006.
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Due to their outstanding mechanical properties, excellent corrosion resistance and biocompatibility titanium and titanium alloys are the first choice for medical engineering products. Alloys currently used for implant applications are Ti-6Al-4V (ELI) and Ti-6Al-7Nb. Both alloys belong to the class of (α+β)-alloys and contain aluminium as an alloying element. Aluminium is cytotoxic and can cause breast cancer. In addition, the stiffness of (α+β)-alloys is relatively high which can lead to stress shielding, bone degradation and implant loss. For this reason, second-generation titanium alloys like Ti-15Mo (solute-lean metastable β-alloy) and Ti-13Nb-13Zr (β-rich (α+β)-alloy) have been developed. However, their application in medical implants is limited due to a relatively low strength. Therefore, in the present study, the mechanical properties of Ti-15Mo and Ti-13Nb-13Zr have been optimised by thermomechanical treatments to achieve high strengths combined with low stiffnesses. Different phase compositions have been used, namely, α-, β- and ω-phase in Ti-15Mo and α-, β- and αʺ-phase in Ti-13Nb-13Zr. For Ti-15Mo, the required mechanical properties’ combination could not be achieved whereas Ti-13Nb-13Zr showed high strength and a low Young’s modulus after a dedicated thermo-mechanical treatment. This makes the latter alloy a good option for replacing the (α+β)-alloys in implant applications in the future.
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Kagawa, Akio, Keishi Katsura, Masayuki Mizumoto, Yutaka Tagawa, and Yoichi Masiko. "Influence of Hydrogen Discharged from Palladium Base Hydrogen Storage Alloys on Cancer Cells." Materials Science Forum 706-709 (January 2012): 520–25. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.520.
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The influence of discharged hydrogen from Pd-Ni based hydrogen storage alloys (HSAs) on cultured cells has been investigated. The susceptibility of cells to discharged hydrogen varied with the kind of cells. No influence was seen in the normal cells, while an effect of killing cancer cells was observed near the HAS and the region where the cell death was observed was limited to an extent of a few mm from the alloy surface. In order to examine the cause of the effects, the amount of gaseous hydrogen and hydrogen radicals released from the alloy surface and pH change of physiological saline aq. solution were measured. The amount of gaseous hydrogen and hydrogen radicals increased with time. The pH of physiological saline aq. solution decreased first and then recovered to the starting value after about 50h. The pH change behavior varied with alloy composition. It is inferred that the hydrogen radicals formed on alloy surface may bring a characteristic change in the cancer cells, leading to the effect of discharged hydrogen on cancer cell death.
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Humud, Hammad R. "Synthesis of Au –Ag– Cu trimetallic alloy nanoparticles prepared by electrical exploding wire technique in distilled water." Iraqi Journal of Physics (IJP) 16, no. 39 (January 5, 2019): 81–92. http://dx.doi.org/10.30723/ijp.v16i39.106.
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Formation of Au–Ag–Cu ternary alloy nanoparticles (NPs) is of particular interest because this trimetallic system have miscible (Au–Ag and Au–Cu) and immiscible (Ag– Cu) system. So there is a possibility of phase segregation in this ternary system. At this challenge it was present attempts synthetic technique to generate such trimetallic alloy nanoparticles by exploding wire technique. The importance of preparing nanoparticles alloys in distilled water and in this technique makes the possibility of obtaining nanoparticles free of any additional chemical substance and makes it possible to be used in the treatment of cancer or diseases resulting from bacterial or virus with least toxic. In this work, three metals alloys Au-Ag-Cu nanoparticles (A, B, and C) were prepared by exploding wire with different ratio of each elements. A high purity wire with diameters (0.3mm) against plate of these alloys were held at 20V with respect to the wire achieving different currents of 75, 100 and 160 A in distilled water and then the size and a shape of the synthesized alloy nanoparticles modify by pulse laser with different energies, where the colloids of nanoparticles were exposed to one thousand pulses of 532 nm wavelengths per pulse from second harmonic Nd-YAG laser, after it has been focused by a lens with 15 cm focal length. The structural properties were studied using x-ray diffraction. It was found that alloy nanoparticles with crystalline structure identical with face center cubic (fcc) and there is a new phase was appear for the A alloy this phase have the name tetragonal AuCu. It can be concludes that electrical explosion wire in liquid medium (EEW) is promising technique for preparation metal alloy Au-Ag-Cu nanoparticles.
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Azmat, Ambreen, Muhammad Tufail, and Ali Dad Chandio. "Synthesis and Characterization of Ti-Sn Alloy for Orthopedic Application." Materials 14, no. 24 (December 12, 2021): 7660. http://dx.doi.org/10.3390/ma14247660.
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Titanium (Ti)-based alloys (e.g., Ti6Al4V) are widely used in orthopedic implant applications owing to their excellent mechanical properties and biocompatibility. However, their corrosion resistance needs to be optimized. In addition, the presence of aluminum and vanadium cause alzheimer and cancer, respectively. Therefore, in this study, titanium-based alloys were developed via powder metallurgy route. In these alloys, the Al and V were replaced with tin (Sn) which was the main aim of this study. Four sets of samples were prepared by varying Sn contents, i.e., 5 to 20 wt. %. This was followed by characterization techniques including laser particle analyzer (LPA), X-ray diffractometer (XRD), scanning electron microscope (SEM), computerized potentiostate, vicker hardness tester, and nanoindenter. Results demonstrate the powder sizes between 50 and 55 µm exhibiting very good densification after sintering. The alloy contained alpha at all concentrations of Sn. However, as Sn content in the alloy exceeded from 10 wt. %, the formation of intermetallic compounds was significant. Thus, the presence of such intermetallic phases are attributed to enhanced elastic modulus. In particular, when Sn content was between 15 and 20 wt. % a drastic increase in elastic modulus was observed thereby surpassing the standard/reference alloy (Ti6Al4V). However, at 10 wt. % of Sn, the elastic modulus is more or less comparable to reference counterpart. Similarly, hardness was also increased in an ascending order upon Sn addition, i.e., 250 to 310 HV. Specifically, at 10 wt. % Sn, the hardness was observed to be 250 HV which is quite near to reference alloy, i.e., 210 HV. Moreover, tensile strength (TS) of the alloys were calculated using hardness values since it was very difficult to prepare the test coupons using powders. The TS values were in the range of 975 to 1524 MPa at all concentrations of Sn. In particular, the TS at 10 wt. % Sn is 1149 MPa which is comparable to reference counterpart (1168 MPa). The corrosion rate of Titanium-Sn alloys (as of this study) and reference alloy, i.e., Ti6Al4V were also compared. Incorporation of Sn reduced the corrosion rate at large than that of reference counterpart. In particular, the trend was in decreasing order as Sn content increased from 5 to 20 wt. %. The minimum corrosion rate of 3.65 × 10−9 mm/year was noticed at 20 wt. % than that of 0.03 mm/year of reference alloy. This shows the excellent corrosion resistance upon addition of Sn at all concentrations.
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Milenin, Andrij, Mirosław Wróbel, Piotr Kustra, Dorota Byrska-Wójcik, Joanna Sulej-Chojnacka, Bartłomiej Płonka, Krzysztof Łukowicz, Karolina Truchan, and Anna Osyczka. "Microstructure and In Vitro Evaluation of Extruded and Hot Drawn Alloy MgCa0.7 for Biodegradable Surgical Wires." Materials 14, no. 21 (November 5, 2021): 6673. http://dx.doi.org/10.3390/ma14216673.
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The MgCa0.7 alloy may be a promising material for biodegradable surgical wires. In this paper, the technology for producing surgical wires from this alloy has been developed, based both on finite element modelling and experimental study. In particular, the extrusion and hot-drawing effects on the mechanical properties, microstructures, in-vitro rates of biocorrosion, and cytotoxicity to human cancer cells (SaOS-2) and healthy (hPDL) ones, have been determined. An approximately 30–40% increase in corrosion rate due to increasing hot-drawing temperature was observed. An effect of hot-drawing temperature on cytotoxicity was also found. Notably, at various stages of the final wires’ production, the MgCa0.7 alloy became toxic to cancer cells. This cytotoxicity depended on the alloys’ processing parameters and was maximal for the as-extruded rod and for the wires immediately after hot drawing at 440 °C. Thus, the careful selection of processing parameters makes it possible to obtain a product that is not only a promising candidate for biodegradable surgical wires, but one which also has intrinsic bioactive properties that produce antitumor activity.
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Dodero, Anna, Francesco Spina, Franco Narni, Francesca Patriarca, Fabio Benedetti, Donatella Baronciani, Alessandro Rambaldi, et al. "Role of Allogeneic Stem Cell Transplantation (AlloSCT) in Patients Affected By Peripheral T-Cell Lymphomas (PTCL): No Difference in Outcome Between Patients Allografted at Diagnosis and in First Chemosensitive Relapse." Blood 124, no. 21 (December 6, 2014): 2574. http://dx.doi.org/10.1182/blood.v124.21.2574.2574.
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Abstract Introduction: Despite novel therapies are under investigation in peripheral T-cell lymphomas (PTCL), the majority of the patients (pts) still have a dismal outcome. AlloSCT seems an effective approach in the salvage setting, but very small series of pts have been transplanted at diagnosis. Methods: We report the long-term outcome (median follow-up of 60 months) of 72 pts affected by PTCL who underwent AlloSCT at diagnosis (Allo1) (n=23) or for chemosensitive relapse (Allo2) (n=49) that have been enrolled in two transplantation protocols. Pathological classification included: 20 PTCL-not otherwise specified (PTCL-NOS), 2 anaplastic large cell lymphoma (ALCL) and 1 rare subtype in Allo1 group; 18 PTCL-NOS, 11 ALCL, 8 AILD and12 rare subtypes in Allo2 group. Donor sources were HLA-matched siblings [n=39: n=13 Allo1 and n=26 Allo2 (p=0.80)], matched or mismatched unrelated donors [n=25: n=10 Allo1 and n=15 Allo2 (p=0.30], and haploidentical family donors [n=8, only in the Allo2 group]. All pts underwent transplant with chemosensitive disease: 45 in complete remission (CR) (63%) [n=20 Allo1, n=25 Allo2 (p=0.003)]; 27 in partial remission (PR) (37%) [n=3 Allo1, n=24 Allo2 (p=0.003)]. In the Allo2 group, 37 pts (75%) were allografted in first relapse and 12 in second relapse. Results: In the Allo1 group, at a median follow-up of 59 months, of the 23 pts 15 (65%) are alive in CR, 4 (17%) died for progressive disease (PD), 3 for non-relapse mortality (NRM, 13%) and 1 for myocardial infarction. In the Allo2 group, at a median follow-up of 64 months, of the 49 pts 31 (63%) are alive (29 in CR), 11 (22%) died for PD and 6 (12%) for NRM while 1 for a second cancer. Five years crude cumulative incidence of relapse was 18% and 38% in Allo1 and Allo2 group (p=0.11), respectively. Five-year relapse-free survival (RFS), progressive-free-survival (PFS), and overall-survival (OS) were as follows: 80%, 60% and 62%, respectively, in Allo1 group; 61%, 47%and 59%, respectively, in Allo2 group without any statistical difference. However, we observed a significant difference in PFS between pts allografted at diagnosis and those in second-relapse (5-year PFS 61% versus 16%, p=0.0044) but not between the allografted at diagnosis and first-relapse (5-year PFS 61% versus 57%, p=0.92). When analyzed pts affected by PTCL-NOS, a better PFS trend was confirmed in pts receiving allograft at diagnosis or in first relapse as compared to second relapse [5-year PFS: 65% versus 55% versus 25%, respectively, (p=0.2)]. Pts who went to alloSCT in first CR did not have a significant advantage [5-year PFS and OS: 59% versus 43% (p=0.44); 60% versus 58% (p=0.82) in Allo1 and Allo2 group, respectively]. Conclusions: Despite the limitations due to the sample size, this is the first analysis in this setting. AlloSCT should be not indicated as a consolidation of first complete or partial remission approach/treatment outside a clinical trial. In fact, AlloSCT is very effective in patients with chemosensitive first relapse. Disclosures No relevant conflicts of interest to declare.
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Azmat, Ambreen, Muhammad Tufail, and Alidad Chandio. "Effect of Niobium on Ti–Sn Alloy for Implant Applications." Journal of Nanoelectronics and Optoelectronics 16, no. 12 (December 1, 2021): 1956–63. http://dx.doi.org/10.1166/jno.2021.3157.
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Titanium (Ti) based alloys (e.g., Ti6Al4V) are extensively utilized in the field orthopedic and dental implant applications due to their enhanced bio-mechanical properties. Nevertheless, their resistance to corrosion requirements needs to be enhanced. Furthermore, existence of vanadium (V) and almunium (Al) elements causes cancer and alzymer respectively. Therefore, in this research Ti-Sn-Nb alloy was produced through the powder metallurgy (PM) route. Tin (Sn) and niobium (Nb) is chosen as an alloying element which replaces toxic Al and V elements. The effect Nb on the Ti–Sn–Nb alloy was studied. Three set of variations of Nb namely 5%, 7.5% & 10% were used for the improvement of properties of parent alloy. The particle dimensions of the parent alloy were analyzed through a laser particle analyzer (LPA). Morphology was studied through Scanning Electron Microscopy (SEM) and phases were determined through X-Ray Diffraction (XRD). Vicker (450SVA) tester was utilized to examine the effect on rigidity after the addition of Nb. The hardness of the alloy was decreasing and corrosion rate was increasing with an increase in Nb content. Furthermore, niobium addition enhances the ability of appetite formation when immersed in the Stimulated body fluid (SBF).
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Xu, W., T. G. Frank, and A. Cuschieri. "Development of a shape memory alloy multiple-point injector for chemotherapy." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 219, no. 3 (March 1, 2005): 213–17. http://dx.doi.org/10.1243/095441105x9354.
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A medical needle is described that allows injection to take place at multiple sites through a single stab wound. This is achieved by extruding multiple, thin, and curved internal needles from a larger, straight, outer needle. The development and finite element modelling of the shape memory alloy (SMA) inner needles is presented in this paper. A non-linear elastic element model was used in this process to allow for the non-linear properties of the alloy and the large deformations that occur. The model provided maximum strain values and penetration forces for the inner needles. The deformation force on the tip of the needle was measured against displacement to confirm the predicted penetration force. Applications for the device include the treatment of liver cancer by direct injection of alcohol into the tumours.
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Becerra, Luis Humberto Campos, and Alejandro Torres Castro. "Bio-Fabrication and Experimental Validation of an Mg - 25Ca - 5Zn Alloy Proposed for a Porous Metallic Scaffold." Crystals 11, no. 11 (November 19, 2021): 1416. http://dx.doi.org/10.3390/cryst11111416.
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This paper proposes the bio-fabrication of a porous scaffold from a selection procedure of elements taking into account biological behavior, using magnesium (Mg) alloyed with calcium (Ca) and zinc (Zn). The proposed scaffold could work as a treatment for specific pathologies in trauma and oncology, on the one hand, in addition to possible applications in osteosynthesis, through contrib-uting to osseointegration and infection control through the release of drugs. Finally, another pos-sible attribute of this alloy could be its use as a complementary treatment for osteosarcoma; this is due to the basification produced by oxidative degradation (attack on cancer cells). The evaluation of cell viability of an alloy of Mg - 25 wt% Ca - 5 wt% Zn will strengthen current perspectives on the use of Mg in the clinical evaluation of various treatments in trauma and oncology. Considera-tions on the preparation of an alloy of Mg - 25 wt% Ca - 5 wt% Zn and its morphological charac-terization will help researchers understand its applicability for the development of new surgical techniques and lead to a deeper investigation of alternative treatments. However, it is very im-portant to bear in mind the mechanical effect of elements such as Ca and Zn on the degradation of the alloy matrix; the best alternative to predict the biological-mechanical potential starts with the selection of the essential-nutritional elements and their mechanical evaluation by mi-cro-indentation due to the fragility of the matrix. Therefore, the morphological evaluation of the specimens of Mg - 25 wt% Ca - 5 wt% Zn will show the crystallinity of the alloy; these results to-gether contribute to the design of biomedical alloys for use in treatments for various medical spe-cialties. The results indicated that cell viability is not affected, and there are no morphological changes in the cells.
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Wood, William A., Allison M. Deal, Bryce B. Reeve, Amy P. Abernethy, Claudio L. Battaglini, Yoon Hie Kim, Julia S. Whitley, et al. "Feasibility of Daily and Weekly Symptom and Health-Related Quality of Life (HRQOL) Surveillance in Patients Receiving Hematopoietic Cell Transplantation (HCT)." Blood 120, no. 21 (November 16, 2012): 4471. http://dx.doi.org/10.1182/blood.v120.21.4471.4471.
Full textAbstract:
Abstract Abstract 4471 Background: Patient-Reported Outcome (PRO) measures help clinicians and researchers monitor symptoms, HRQOL, satisfaction, and adherence related to cancer treatment. Symptoms affect HRQOL, and when both are reported frequently and longitudinally, a patient-reported data stream emerges that reflects physiological functioning and complements traditional laboratory and clinician-based assessments. Such data could significantly enhance risk prediction and safety monitoring in patients undergoing HCT. This study evaluates the feasibility of collecting daily and weekly PRO measurements to inform our ability to capture variation in patient experiences over time. Patients and methods: We enrolled 32 patients undergoing planned HCT (10 autologous, 11 myeloablative allogeneic, 11 reduced intensity allogeneic) in a feasibility study of frequent HRQOL and symptom surveillance following HCT. All surveys were administered electronically though patients could opt for pen and paper. PRO measures were derived from the NIH PROMIS and PRO-CTCAE measures, which have not been previously used extensively or at all in HCT patients. All patients completed a 10-question HRQOL measure (PROMIS-Global Health) and a 34-question symptom measure (a pre-selected subset of the 83-question PRO-CTCAE, with 7-day recall period) prior to HCT and weekly until D+100. Auto patients completed a daily 21-question symptom measure (a pre-selected subset of the weekly symptom surveys, with 24-hour recall period) until hospital discharge, and allo patients completed daily symptom surveys until 100 days after stem cell infusion (D+100). Kruskal-Wallis tests were used to compare groups. Median age of the sample was 55 years (range 18–70). 16 patients (50%) were female. Most auto patients had myeloma (N=8, 80%) and most allo patients had acute leukemia (16, 72%); other diagnoses included NHL (4), CML, MDS and AA. Twenty-six (81%) patients were Caucasian, 4 (12.5%) were African American, 2 were other (6.2%). Thirteen (41%) had a high school education or lower. Results: Median daily survey completion percentages prior to hospital discharge for surviving patients were 94% among auto patients, 90% among reduced intensity allo patients and 70% among myeloablative allo patients (p=0.07). Prior to D+100, median daily survey completion percentages were 87% among reduced intensity allo patients and 58% among myeloablative allo patients (p=0.004). Median weekly survey completion percentages prior to hospital discharge were 100% in all cohorts. Prior to D+100, these were 100% in auto and reduced intensity allo cohorts, and 80% among myeloablative allo patients (p=0.002). Daily surveys were completed in a median of 3 minutes, and longer weekly surveys in a median of 4.3 minutes. 93% of respondents were satisfied with survey length and 85% of respondents were satisfied with the electronic self-report system. Median weekly total symptom scores (higher scores indicated greater symptom severity) prior to conditioning were 16 in autos, 12 in myeloablative allos, and 5 in reduced intensity allos (p=0.3) and at D+7 were 23 in autos, 40 in myeloablative allos and 18 in reduced intensity allos (p=0.01). For the physical health subscale of the PROMIS measure (lower scores indicated greater impairment), baseline mean weekly HRQOL scores were 47.7 in autos, 50.8 in myeloablative allos and 50.8 in reduced intensity allos (p=0.9). By D+7, mean HRQOL scores were 37.4 in autos, 37.4 in myeloablative allos and 52.5 in reduced intensity allos (p=0.005). Conclusion: Frequent symptom and HRQOL surveillance is feasible and acceptable to HCT patients, and survey data correlates with toxicity and physiological function after transplant. Compliance rates were lower in myeloablative allo patients, especially for daily surveys, perhaps reflecting the higher burden of critical illness in this population. Future studies may be enhanced by caregiver-reported proxy data. Analyses of weekly symptom and HRQOL surveys beyond D+7, daily surveys, symptom clusters, biologic correlates and individualized profiles are ongoing. Larger studies are warranted to explore and develop risk prediction models based on this technique. Disclosures: No relevant conflicts of interest to declare.
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Greil, Christine, Monika Engelhardt, Jürgen Finke, and Ralph Wäsch. "Allogeneic Stem Cell Transplantation in Multiple Myeloma." Cancers 14, no. 1 (December 23, 2021): 55. http://dx.doi.org/10.3390/cancers14010055.
Full textAbstract:
The development of new inhibitory and immunological agents and combination therapies significantly improved response rates and survival of patients diagnosed with multiple myeloma (MM) in the last decade, but the disease is still considered to be incurable by current standards and the prognosis is dismal especially in high-risk groups and in relapsed and/or refractory patients. Allogeneic hematopoietic stem cell transplantation (allo-SCT) may enable long-term survival and even cure for individual patients via an immune-mediated graft-versus-myeloma (GvM) effect, but remains controversial due to relevant transplant-related risks, particularly immunosuppression and graft-versus-host disease, and a substantial non-relapse mortality. The decreased risk of disease progression may outweigh this treatment-related toxicity for young, fit patients in high-risk constellations with otherwise often poor long-term prognosis. Here, allo-SCT should be considered within clinical trials in first-line as part of a tandem approach to separate myeloablation achieved by high-dose chemotherapy with autologous SCT, and following allo-SCT with a reduced-intensity conditioning to minimize treatment-related organ toxicities but allow GvM effect. Our review aims to better define the role of allo-SCT in myeloma treatment particularly in the context of new immunomodulatory approaches.
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Kaupp, Gerd. "Scanning near-field optical microscopy on rough surfaces: Applications in chemistry, biology, and medicine." International Journal of Photoenergy 2006 (2006): 1–22. http://dx.doi.org/10.1155/ijp/2006/69878.
Full textAbstract:
Shear-force apertureless scanning near-field optical microscopy (SNOM) with very sharp uncoated tapered waveguides relies on the unexpected enhancement of reflection in the shear-force gap. It is the technique for obtaining chemical (materials) contrast in the optical image of “real world” surfaces that are rough and very rough without topographical artifacts, and it is by far less complicated than other SNOM techniques that can only be used for very flat surfaces. The experimental use of the new photophysical effect is described. The applications of the new technique are manifold. Important mechanistic questions in solid-state chemistry (oxidation, diazotization, photodimerization, surface hydration, hydrolysis) are answered with respect to simultaneous AFM (atomic force microscopy) and detailed crystal packing. Prehistoric petrified bacteria and concomitant pyrite inclusions are also investigated with local RAMAN SNOM. Polymer beads and unstained biological objects (rabbit heart, shrimp eye) allow for nanoscopic analysis of cell organelles. Similarly, human teeth and a cancerous tissue are analyzed. Bladder cancer tissue is clearly differentiated from healthy tissue without staining and this opens a new highly promising diagnostic tool for precancer diagnosis. Industrial applications are demonstrated at the corrosion behavior of dental alloys (withdrawal of a widely used alloy, harmless substitutes), improvement of paper glazing, behavior of blood bags upon storage, quality assessment of metal particle preparations for surface enhanced RAMAN spectroscopy, and determination of diffusion coefficient and light fastness in textile fiber dyeing. The latter applications include fluorescence SNOM. Local fluorescence SNOM is also used in the study of partly aggregating dye nanoparticles within resin/varnish preparations. Unexpected new insights are obtained in all of the various fields that cannot be obtained by other techniques.
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Globig, Philipp, Regine Willumeit-Römer, Fernanda Martini, Elisa Mazzoni, and Bérengère J. C. Luthringer-Feyerabend. "Optimizing an Osteosarcoma-Fibroblast Coculture Model to Study Antitumoral Activity of Magnesium-Based Biomaterials." International Journal of Molecular Sciences 21, no. 14 (July 19, 2020): 5099. http://dx.doi.org/10.3390/ijms21145099.
Full textAbstract:
Osteosarcoma is among the most common cancers in young patients and is responsible for one-tenth of all cancer-related deaths in children. Surgery often leads to bone defects in excised tissue, while residual cancer cells may remain. Degradable magnesium alloys get increasing attention as orthopedic implants, and some studies have reported potential antitumor activity. However, most of the studies do not take the complex interaction between malignant cells and their surrounding stroma into account. Here, we applied a coculture model consisting of green fluorescent osteosarcoma cells and red fluorescent fibroblasts on extruded Mg and Mg–6Ag with a tailored degradation rate. In contrast to non-degrading Ti-based material, both Mg-based materials reduced relative tumor cell numbers. Comparing the influence of the material on a sparse and dense coculture, relative cell numbers were found to be statistically different, thus relevant, while magnesium alloy degradations were observed as cell density-independent. We concluded that the sparse coculture model is a suitable mechanistic system to further study the antitumor effects of Mg-based material.