Segui questo link per vedere altri tipi di pubblicazioni sul tema: Carbides.
Articoli di riviste sul tema "Carbides"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 articoli di riviste per l'attività di ricerca sul tema "Carbides".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi gli articoli di riviste di molte aree scientifiche e compila una bibliografia corretta.
1
De Bonis, Angela, Mariangela Curcio, Antonio Santagata, Agostino Galasso e Roberto Teghil. "Transition Metal Carbide Core/Shell Nanoparticles by Ultra-Short Laser Ablation in Liquid". Nanomaterials 10, n. 1 (14 gennaio 2020): 145. http://dx.doi.org/10.3390/nano10010145.
Testo completoAbstract (sommario):
Transition metal carbide nanoparticles are a class of technological interesting materials with a wide range of applications. Among metal carbides, tantalum carbides have good compatibility with the biological environment while molybdenum carbides are used as catalyst in electrochemical reactions. Laser ablation of bulk transition metal targets in some liquids is here reported and laser ablation in organic solvents is used as simple synthetic strategy for the production of carbide nanostructures. Herein, the nanoparticles produced by ultra-short laser ablation of tantalum and molybdenum in water, acetone, ethanol and toluene have been characterized by TEM, XRD and XPS analysis. The combined effect of metal and solvent chemical and physical properties on the composition of the nanomaterials obtained has been pointed out. In particular, the different reactivity of Ta and Mo with respect to oxidizing species determines the composition of particles obtained in water, on the other hand the organic solvents decomposition allows to obtain transition metal carbide (TMC) nanoparticles. The observed carbonaceous shell formed on TMC allows to protect the particle’s carbidic core and to improve and tailor the applications of these nanomaterials.
2
Wang, Xijie, Guangqiang Li, Yu Liu, Yulong Cao, Fang Wang e Qiang Wang. "Investigation of Primary Carbides in a Commercial-Sized Electroslag Remelting Ingot of H13 Steel". Metals 9, n. 12 (21 novembre 2019): 1247. http://dx.doi.org/10.3390/met9121247.
Testo completoAbstract (sommario):
The characteristics of primary carbides in a commercial-sized (one ton) electroslag remelting (ESR) ingot of AISI H13 steel were investigated. The interaction between the primary carbides and inclusions was also clarified. The results indicate that there are two types of primary carbides, V-rich and Mo-rich primary carbides, in the H13 ESR ingot. The quantity, the area fraction, and the size of the two primary carbides tend to decrease from the center of the H13 ESR ingot to the outer surface. Additionally, the V-rich primary carbide is obviously larger than the Mo-rich primary carbide. The Al2O3 inclusion can promote the precipitation of the V-rich primary carbide, while the MnS inclusion encourages the precipitation of Mo-rich primary carbide. The CaO∙Al2O3 inclusion cannot act as the nucleation site for the precipitation of the two primary carbides. The solid fraction that the V-rich primary carbide begins to precipitate ranges from 0.965 to 0.983, and that for the Mo-rich primary carbide and the MnS inclusion change from 0.9990 to 0.9998 and from 0.989 to 0.990, respectively.
3
Huang, Yu, Guoguang Cheng e Meiting Zhu. "Effect of Ti Content on the Behavior of Primary Carbides in H13 Ingots". Metals 10, n. 6 (24 giugno 2020): 837. http://dx.doi.org/10.3390/met10060837.
Testo completoAbstract (sommario):
The Ti element plays a role in pinning grain boundaries but also has a good binding ability to C and N, forming large primary carbides. Therefore, the effect of Ti content on primary carbides’ behavior in H13 ingots was comprehensively studied. A non-aqueous electrolysis method was used to determine the three-dimensional (3D) characteristics of primary carbides. We found a great difference between the two-dimensional (2D) and the three-dimensional characteristics of primary carbides. When performing 2D analyses, the density of the primary carbides appeared high, while their size was small. The actual characteristics of primary carbides can be obtained only by 3D observation. The primary carbide showed a typical dendritic structure, whose center consisted of Ti–V-rich carbide wrapped by V-rich carbide. As the Ti content increased, the size of the primary carbide increased from 24.9 μm to 41.3 μm, and the number density increases from 25.6 per/mm2 to 43.9 per/mm2. The Ti4C2S2 phase precipitated first, then changed into Ti–V-rich carbide, and finally further partly transformed into V-rich carbide. The addition of elemental Ti promoted the precipitation and transformation of primary carbides, resulting in an increase of the number density and size.
4
Maddi, Lakshmiprasad, e Ajay Likhite. "Advances in Carbidic Austempered Ductile Iron (CADI) - A Wearresistant Material". Current Materials Science 14, n. 2 (12 agosto 2021): 114–24. http://dx.doi.org/10.2174/2666145414666210423125555.
Testo completoAbstract (sommario):
Background: Ductile irons provide a more viable alternative for malleable cast iron in areas that do not demand extreme wear resistance. Austempering of ductile irons was a well researched area in the last two decades. Attempts to further improve the wear resistance led to the development of Carbidic austempered ductile iron (CADI), wherein the carbides contribute to wear resistance. Combination of ausferritic matrix, graphite nodules, and carbides (eutectic and alloy) symbolizes the microstructure of CADI. Methods: Two principal approaches adopted by the researchers to change the microstructure are (i) addition of carbide forming elements (ii) heat treatment (s). Results: Both the above methods result in the refinement of graphite nodules, carbide precipitations, along fine ausferrite. Conclusion: Improvement in hardness, toughness and wear resistance was observed largely as a consequence of fine carbide precipitations and formation of martensite.
5
Byeon, Jai Won, S. I. Kwun e Kae Myung Kang. "Assessment of Mechanical Degradation in Pressure Vessel Steel by Morphological Analysis of Carbides". Key Engineering Materials 321-323 (ottobre 2006): 561–64. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.561.
Testo completoAbstract (sommario):
In this study, mechanical degradations in 2.25Cr-1Mo steel were evaluated by quantitative morphological analysis of carbides. Based on the morphology, carbides were classified as globular, fine acicular, rod, and grain boundary one. Mean size of carbides were determined as a function of morphology and thermal degradation time at 630°C. Area fraction of grain boundary carbides and fraction of grain boundary M6C carbides were observed to increase rapidly in the initial stage of degradation and then gradually afterwards. Both mean size of globular carbide and fraction of grain boundary M6C carbides were linearly correlated with strength. Potentials of carbide morphology analysis as a health monitoring technique were discussed, in term of correlation coefficient with strength.
6
Jaworski, J., R. Kluz e T. Trzepieciński. "Influence of Heat Treatment on Content of the Carbide Phases in the Microstructure of High-Speed Steel". Archives of Foundry Engineering 17, n. 3 (1 settembre 2017): 59–62. http://dx.doi.org/10.1515/afe-2017-0091.
Testo completoAbstract (sommario):
Abstract This article presents the results of investigations of the effect of heat treatment temperature on the content of the carbide phase of HS3-1-2 and HS6-5-2 low-alloy high-speed steel. Analysis of the phase composition of carbides is carried out using the diffraction method. It is determined that with increasing austenitising temperature, the intensification of dissolution of M6C carbide increases. As a result, an increase in the grain size of the austenite and the amount of retained austenite causes a significant reduction in the hardness of hardened steel HS3-1-2 to be observed. The results of diffraction investigations showed that M7C3 carbides containing mainly Cr and Fe carbides and M6C carbides containing mainly Mo and W carbides are dissolved during austenitisation. During austenitisation of HS3-1-2 steel, the silicon is transferred from the matrix to carbides, thus replacing carbide-forming elements. An increase in a degree of tempering leads to intensification of carbide separation and this process reduce the grindability of tested steels.
7
Lee, Junmo, Taekyung Lee, Young Jin Kwon, Dong-Jun Mun, Jang-Yong Yoo e Chong Soo Lee. "Role of Mo/V carbides in hydrogen embrittlement of tempered martensitic steel". Corrosion Reviews 33, n. 6 (1 novembre 2015): 433–41. http://dx.doi.org/10.1515/corrrev-2015-0052.
Testo completoAbstract (sommario):
AbstractThe vulnerability of tempered martensitic steel to hydrogen embrittlement (HE) has attracted attention from a number of researchers. Although utilizing carbide precipitation is one of effective methods to improve HE resistance, few studies have focused on the effects of carbide characteristics, such as the chemical composition and morphology of carbide. This work clarifies the role of Mo carbide and V carbide in the HE behavior of tempered martensitic steels with four steels whose chemical composition was carefully controlled. The beneficial effect of carbides is discussed in terms of hydrogen trapping and fracture mode. The low amount of trapped hydrogen and undissolved carbide led to excellent HE resistance of Mo carbides compared to V carbides. In addition, the superior mechanical performance of Cr-Mo steel was also interpreted by the effect of Cr addition as well as Mo carbides.
8
He, Bao, Jing Li, Cheng-bin Shi e Hao Wang. "Effect of Mg addition on carbides in H13 steel during electroslag remelting process". Metallurgical Research & Technology 115, n. 5 (2018): 501. http://dx.doi.org/10.1051/metal/2018071.
Testo completoAbstract (sommario):
The effect of Mg on carbides precipitation in H13 steel was studied based on the Thermo-Calc thermodynamic calculation. The results showed that the precipitation temperature of MC phase was significantly improved by adding Mg. The Mg addition had no effect on the type of precipitated carbides. The as-cast microstructure and the characteristic of carbides in Mg-containing H13 steel were analyzed by OM and SEM-EDS. The results showed that the segregation of as-cast microstructure was released and the size of carbides was reduced by increasing Mg. The distribution of carbides was more homogeneous. The formed MgO · Al2O3 arising from Mg treatment provided preferred nucleation site for TiN, which was the core of heterogeneous nucleation of carbides, resulted in decreasing the size of carbides. Furthermore, partial Mg would melt into the carbides, which would change the morphology of carbide and induce the formation of leaf-like carbides. The electron probe micro-analysis (EPMA) results showed that the segregation of V and Mo in H13 steel was inhibited by Mg, and the dissolved Mg in carbide promoted the heterogeneous nucleation of carbides.
9
Rivero, H. D., José A. García, E. Cándido Atlatenco, Alejandro D. Basso e J. Sicora. "Effect of the ratio Mo/Cr in the precipitation and distribution of carbides in alloyed nodular iron". MRS Proceedings 1485 (2012): 113–18. http://dx.doi.org/10.1557/opl.2013.278.
Testo completoAbstract (sommario):
ABSTRACTThis investigation deals with the effect of 2/0, 1/1 and 1/0.5 Cr/Mo ratios on the local fraction, distribution and the comparative size of carbides precipitated in cast nodular iron. “Y” block castings with a thickness of 1.5 cm are cast in green sand molds. Two samples are cut from each casting, one located on the center and another on the wall. The carbide volume fraction is evaluated by a digital analysis system. Each sample is analyzed in three zones: bottom, middle and top. Carbide mappings are generated according to the average local carbide fraction in order to get the distribution of carbides on the casting. Results show that higher volume fractions of carbides precipitate for the ratio 2/0 of Cr/Mo with values between 28.5 and 19.5%. The lowest fraction of carbides is presented in nodular iron alloyed with a Cr/Mo ratio of 1/1 between 6.5 and 4.6%. Also a very heterogeneous distribution of the carbides is observed in the three alloys and massive carbides are observed in the last freezing zone of the castings.
10
Thuvander, Mattias, Hans Magnusson e Ulrika Borggren. "Carbide Precipitation in a Low Alloyed Steel during Aging Studied by Atom Probe Tomography and Thermodynamic Modeling". Metals 11, n. 12 (13 dicembre 2021): 2009. http://dx.doi.org/10.3390/met11122009.
Testo completoAbstract (sommario):
Carbide precipitation in martensitic low alloyed steels contributes to the mechanical properties through precipitation hardening. A high number density of carbides is desired to maximize the hardening effect, which is achieved through the precipitation of carbides on the dislocations in the martensitic structure. In this study, the nucleation, growth, and coarsening of vanadium and molybdenum carbides during aging at 600 °C for periods up to four weeks were investigated. The work covers characterization with atom probe tomography, which showed that the nucleation of V and Mo rich MC/M2C carbides takes place on dislocations. The growth of these carbides proceeds by the diffusion of elements to the dislocations, which has been modeled using Dictra software, confirming the rate of the reaction as well as the depletion of carbide formers in the matrix. For longer aging times, particle coarsening will decrease the number density of particles with a transition from dislocation-based carbides to separate rounded carbides.
11
Xie, Yixin, Xiaonong Cheng, Jiabo Wei e Rui Luo. "Characterization of Carbide Precipitation during Tempering for Quenched Dievar Steel". Materials 15, n. 18 (16 settembre 2022): 6448. http://dx.doi.org/10.3390/ma15186448.
Testo completoAbstract (sommario):
Carbide precipitation and coarsening are investigated for quenched Dievar steel during tempering. Lath/lenticular martensite, retained austenite, lower bainite, auto-tempered, and larger spherical carbides are all observed in the as-quenched condition. The carbide precipitation sequence on tempering is ascertained to be: M8C7 + cementite → M8C7 + M2C + M7C3 → M8C7 + M7C3 + M23C6 → M8C7 + M7C3 + M23C6 + M6C; carbides become coarser on tempering, and the sizes for inter-lath carbides increase noticeably with increasing tempering temperatures due to the faster grain boundary diffusion, whereas the sizes for intra-lath carbides remain nearly constant. The rate of coarsening for carbides by tempering at 650 °C is much higher than those by tempering at 550 °C and 600 °C, due to the faster diffusion of alloying elements at higher temperatures.
12
Adaskina, A. M., S. N. Grigoriev, A. A. Vereschaka, A. S. Vereschaka e V. V. Kashirtsev. "Cemented Carbides for Machining of Heat-Resistant Materials". Advanced Materials Research 628 (dicembre 2012): 37–42. http://dx.doi.org/10.4028/www.scientific.net/amr.628.37.
Testo completoAbstract (sommario):
The optimum ratio of rhenium and cobalt in Co-Re binder of a cemented carbides based on the analysis of phase diagrams and studying the carbides properties is defined.It is shown that properties of carbide binder at the same ratio of rhenium and cobalt are also the same, and the carbide properties are determined by the amount of carbide binders.Researches of wear resistance of the tool from carbides with Co-Re binder at machining of a constructional steel and hard-to-machining alloys have confirmed their high efficiency.
13
Chen, Yangmin, Chenghuan Ye, Xiangru Chen, Qijie Zhai e Henry Hu. "Effect of Alloying and Microalloying Elements on Carbides of High-Speed Steel: An Overview". Metals 14, n. 2 (1 febbraio 2024): 175. http://dx.doi.org/10.3390/met14020175.
Testo completoAbstract (sommario):
In high-speed steel, carbides are essential phase constituents, which have a direct impact on engineering performance and qualities of high-speed steel. The formation, morphology, and distribution of carbides are dictated by alloying elements. In this paper, various types of carbides in high-speed steel are presented. The effects of different alloying elements such as C, W, Mo, Cr, and V on the formation of carbides in high-speed steel are discussed. Research progresses on carbide improvement by microalloying elements such as N, B, Mg, and rare earth (RE) elements are reviewed. It is reported that Cr promotes the precipitation of M2C, N enhances the formation of fibrous M2C, Mg effectively shatters the large-size carbide grid, Nb refines granular carbide MC, and rare earth elements encourage the formation of M6C, resulting in irregular M2C lamellae. The incorporation of microalloying elements improves the distribution and size of carbides and also refines the solidification structure of high-speed steel.
14
Abdulazizov, Tilebaldy Adilovich, Abduraim Satyvaldievich Satyvaldiev e Kalyskan Imatali kyzy. "Oxidation of cubic complex carbides (Ti xVyMoz)C synthesis by electrospark dispersion method with atmospheric oxygen". E3S Web of Conferences 537 (2024): 05011. http://dx.doi.org/10.1051/e3sconf/202453705011.
Testo completoAbstract (sommario):
During the joint electrospark dispersion of titanium with VyMoz alloys in hexane, complex carbides (TixVyMoz)C with a cubic lattice are formed. Assuming that complex carbides (TixVyMoz)C as quasi-binary systems, where complex carbide (VyMoz)C with a cubic structure is dissolved in cubic titanium monocarbide, the composition of complex carbides (Ti0,75V0,05Mo0,20)C and (Ti0,65V0,31Mo0,04)C, formed by electrospark dispersion of Ti-V0,2Mo0,8 and Ti-V0,2Mo0,8 pairs. Using the method of differential thermal analysis, it was shown that the thermal stability against oxidation of complex carbides (TixVyMoz)C, synthesized by joint electrospark dispersion of titanium and the VyMoz alloy, depends on the ratio of metals. Thermal stability against oxidation increases with an increase in the content of titanium and molybdenum in the composition of complex carbides; their resistance to oxidation increases. It has been established that intensive oxidation of complex carbide (Ti0,75V0,05Mo0,20)C occurs at 595oC, and complex carbide (Ti0,65V0,31Mo0,04)C oxidizes at the maximum rate at 520oC.
15
Wang, Ming Yue, Jing Jing Wang, Yan Lin He, Xiao Gang Lu e Lin Li. "Experimental Study and Calculation of the Precipitation Behavior of Carbides in Fe-5.78Cr-0.35C Alloy during High-Temperature Aging". Advanced Materials Research 936 (giugno 2014): 1184–88. http://dx.doi.org/10.4028/www.scientific.net/amr.936.1184.
Testo completoAbstract (sommario):
The precipitation behavior of carbides in Fe-5.78Cr-0.35C (wt.%) alloy during aging at 850°C was studied. The type, particle size and distribution of carbides were determined and measured by the combination of HRTEM (High Resolution Transmission Electron Microscope), XRD (X-Ray Diffraction) and quantitative metallography technique. Results show that the type of carbides was M7C3 and the obvious coarsening of carbides was observed during aging. In addition, the thermodynamic and kinetic calculation using Thermo-Calc software was conducted to study the precipitation of carbides. The stable phase in the alloy aging at 850°C was M7C3 carbide and austenite which is in accordance with experimental results. According to Ostwald coarsening mechanism, the average interfacial energy between γ phase and M7C3 carbide was calculated as 0.7 J·m-2. Then the precipitation behavior of carbides in Fe-5.78Cr-0.35C alloy during aging was well predicted.
16
Zhang, Weiguo, Xiaowei Wu, Jun Tian, Xi Huang, Wentao Yu, Wenchao Zhu e Jingwen He. "Improving Wear Resistance and Corrosive Resistance of Cemented Carbide for Mud Pulser Rotor by Deep Cryogenic Treatment". Materials 17, n. 5 (4 marzo 2024): 1195. http://dx.doi.org/10.3390/ma17051195.
Testo completoAbstract (sommario):
Cemented carbide used in the rotor of a mud pulser is subjected to the scouring action of solid particles and corrosive mud media for a long time, which causes abrasive wear and electrochemical corrosion. To improve the wear and corrosive resistance of cemented carbide, samples with different cobalt content (WC-5Co, WC-8Co, and WC-10Co) receive deep cryogenic treatment (DCT) at −196 °C for 2.5 h. An optical metalloscope (OM) and X-ray diffractometer (XRD) are used to observe the phase changes of cemented carbides, and the XRD is also used to observe the change in residual stress on the cemented carbide’s surface. A scanning electron microscope (SEM) is used to characterize the wear and electrochemical corrosion surface microstructure of cemented carbides (untreated and DCT). The results show that the DCT promotes the precipitation of the η phase, and the diffraction peak of ε-Co tends to intensify. Compared with the untreated, the wear rates of WC-5Co, WC-8Co, and WC-10Co can be reduced by 14.71%, 37.25%, and 41.01% by DCT, respectively. The wear form of the cemented carbides is mainly the extrusion deformation of Co and WC shedding. The precipitation of the η phase and the increase in WC residual compressive stress by DCT are the main reasons for the improvement of wear resistance. The electrochemical corrosion characteristic is the dissolution of the Co phase. DCT causes the corrosion potential of cemented carbide to shift forward and the corrosion current density to decrease. The enhancement of the corrosion resistance of cemented carbide caused by DCT is due to the Co phase transition, η phase precipitation, and the increase in the compressive stress of cemented carbide.
17
Papaefthymiou, Spyros, Marianthi Bouzouni e Roumen H. Petrov. "Study of Carbide Dissolution and Austenite Formation during Ultra–Fast Heating in Medium Carbon Chromium Molybdenum Steel". Metals 8, n. 8 (16 agosto 2018): 646. http://dx.doi.org/10.3390/met8080646.
Testo completoAbstract (sommario):
In this study, UltraFast Heat Treatment (UFHT) was applied to a soft annealed medium carbon chromium molybdenum steel. The specimens were rapidly heated and subsequently quenched in a dilatometer. The resulting microstructure consists of chromium-enriched cementite and chromium carbides (in sizes between 5–500 nm) within fine (nano-sized) martensitic and bainitic laths. The dissolution of carbides in austenite (γ) during ferrite to austenite phase transformation in conditions of rapid heating were simulated with DICTRA. The results indicate that fine (5 nm) and coarse (200 nm) carbides dissolve only partially, even at peak (austenitization) temperature. Alloying elements, especially chromium (Cr), segregate at austenite/carbide interfaces, retarding the dissolution of carbides and subsequently austenite formation. The sluggish movement of the austenite /carbide interface towards austenite during carbide dissolution was attributed to the partitioning of Cr nearby the interface. Moreover, the undissolved carbides prevent austenite grain growth at peak temperature, resulting in a fine-grained microstructure. Finally, the simulation results suggest that ultrafast heating creates conditions that lead to chemical heterogeneity in austenite and may lead to an extremely refined microstructure consisting of martensite and bainite laths and partially dissolved carbides during quenching.
18
Skakov, Маzhyn, Bauyrzhan Rakhadilov e Gaukhar Karipbayeva. "Specifics of Microstructure and Phase Composition of High-Speed Steel R6M5". Applied Mechanics and Materials 404 (settembre 2013): 20–24. http://dx.doi.org/10.4028/www.scientific.net/amm.404.20.
Testo completoAbstract (sommario):
In this paper microstructure, morphology, elemental composition, phase composition and crystal structure of the sample steel R6M5 were investigate by using the methods of scanning electron microscopy, electron backscatter diffraction (EBSD) analysis and X-ray diffraction (XRD) analysis. Determined that the microstructure of steel R6M5 after hardening and three-time tempering consists of tempered martensite and solid carbide M6C and MC-type with spherical shape and a diameter of less than 3 μm. Detected that the volume fraction of each carbide amounted to 10.4±0.6% and 2.3±0.4% - for grey and bright carbides, respectively, and that the sizes of bright carbides particles in the microstructure of steel R6M5 are 0.4-4,5 μm, and the sizes of grey carbides particles are 0.5-1.1 μm. XRD analysis showed that the main carbides in the studied steel are carbides М6С and MC, which have complicated the FCC crystal lattice and the Fd3m spatial group. Determined that carbides are uniform and monocrystalline. ESBD analysis with the support of the XRD analysis showed that carbides spherical shape М6С fit to Fe3W3C composition.
19
Liu, Li Rong, Shuo Han, Yi Fan Pu, Zhi Jiang Peng e Ming Jun Zhang. "Morphological Evolution of Carbides in DZ125 Superalloy during Heat Treatment". Materials Science Forum 879 (novembre 2016): 1153–58. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1153.
Testo completoAbstract (sommario):
Morphological evolution of carbides in DZ125 superalloy during heat treatment was investigated by using SEM and EDS. The results show that in DZ125 directionally solidified superalloy, the MC carbide is either smooth platelet or bone-shaped structure with nodes in morphology in as-cast state, which is rich in Ta, Ti and Hf. During solid solution treatment, parts of primary MC carbides dissolve, so that the morphology of MC carbide changes from smooth and regular surface to scattered configuration. During aging heat treatment and long term aging, the secondary MC carbides enriched in Hf element precipitated from the matrix. Moreover, there is some M6C carbide enriched in W element precipitated on the grain boundary. With the process of heat treatment, the content of Hf element in MC carbides increases obviously.
20
Dai, Yu Mei, e Yong Qing Ma. "Study on Effects of Pretreatment on Carbide of a Medium-Alloy High Carbon Steel". Advanced Materials Research 194-196 (febbraio 2011): 271–74. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.271.
Testo completoAbstract (sommario):
The effect of pre-treatment on carbide transformation and morphology of a medium-alloy high carbon steel (0.86C, 0.84Cr, 1.85W, 0.95Mo, 0.31V) with multi-elements was investigated in this paper. The results show that there are multiple types of carbides (M3C、M23C6、M7C3、M6C、MC) in the annealed steel. The morphology of carbide in the annealing microstructure largely relate to the process before annealing. Carbides with disperse spherical and short rod-like distribution exist in the ferritic matrix when the steels are annealed at 820−860°C. The spherical carbides in the ferritic matrix can be obtained by isothermal annealing at 680−720°C after heating at 800°C. The morphology of carbides with different pretreatment process relate to carbide transformation, which can be described by calculating based on phase equilibrium thermodynamic.
21
Penghui, Yang, Hanguang Fu, Lin Jian, Cheng Haiqiang e Lei Yongping. "Experimental and ab initio study of the influence of a compound modifier on carbidic ductile iron". Metallurgical Research & Technology 116, n. 3 (2019): 306. http://dx.doi.org/10.1051/metal/2018124.
Testo completoAbstract (sommario):
To improve the morphology of carbides in carbidic ductile iron, a compound modifier consisting of 0.1% Nb + 0.1% Ti + 0.1 wt.% Y was added to the base ductile iron with chemical composition of 3.72% C, 2.77% Si, 0.51% Mn, 0.99% Cr and balance Fe (wt.%). The effect of this compound modifier on the microstructures of carbidic ductile iron was studied. Also, first-principles calculations were carried out to better understand the modification mechanisms. The results showed that the maximum diameter of spheroidal graphite nodules decreased from 58 to 34 µm after the addition of compound modifier, and continuous carbide networks changed into a broken network. The roundness of graphite nodules decreased slightly, and the percent nodularity of the graphite nodules and the number of carbides decreased by 3 and 1.8%, respectively. Compounds with higher melting point are formed thanks to the compound modifier which acts as heterogeneous core, and the remaining Ti and Nb elements can be selectively attracted by (010) surface of Fe8Cr4C4. Furthermore, Cr elements can be easily replaced by Ti and Nb in the carbides to form more stable Fe8Cr3TiC4 and Fe8Cr3NbC4, which can prevent the continuing growth of carbide on the Fe8Cr4C4 (010) crystal surface and break the continuous network M3C. Y atoms cannot be directly adsorbed onto Fe8Cr4C4 (010) surfaces. They combine first with oxygen in the ductile iron to form Y2O3. The work of adhesion of the interface between a Y2O3 (100) and a Fe8Cr4C3 (010) is predicted to be 0.3 J/m2. The addition of Y element is found to have a positive effect on breaking up the continuity of the carbide network.
22
Lv, Yanan, e Weimin Gao. "Crystal structural and diffusion property in titanium carbides: A molecular dynamics study". Modern Physics Letters B 30, n. 26 (30 settembre 2016): 1650334. http://dx.doi.org/10.1142/s0217984916503346.
Testo completoAbstract (sommario):
Titanium carbides were studied via molecular dynamics simulation to characterize TiC[Formula: see text] structures with respect to the carbon diffusion properties in this study. The effect of carbon concentration on atomic structures of titanium carbides was investigated through discussing the structure variation and the radial distribution functions of carbon atoms in titanium carbides. The carbon diffusion in titanium carbides was also analyzed, focusing on the dependence on carbon concentration and carbide structure. Carbon diffusivity with different carbon concentrations was determined by molecular dynamics (MD) calculations and compared with the available experimental data. The simulation results showed an atomic exchange mechanism for carbon diffusion in titanium carbide.
23
Zeng, Qiang, Ping Yan, Jing Chen Zhao, Long Fei Zhang e Lian Li. "Coarsening Behavior of Precipitates in a Conventional Cast Nickel Base Superalloy during Long Term Thermal Exposure". Materials Science Forum 788 (aprile 2014): 452–58. http://dx.doi.org/10.4028/www.scientific.net/msf.788.452.
Testo completoAbstract (sommario):
A long term aging treatment at 900oC for 3000h was carried out on a conventional cast nickel base superalloy with standard solution and aging treatment. The microstructural evolution including the phases within grains and at grain boundaries (GBs) during thermal exposure in the alloy was observed using OM and SEM. It was shown that the major phases in the alloy after standard heat treatment were γ' precipitates and coarse blocky MC carbides, both of which were distributed not only within grains but also at GBs. During aging, the size of MC carbides and γ' precipitates both within grains and at GBs increased with increasing aging time. It was found that two characteristics of MC carbide and γ' precipitates evolved with aging time: the one is that the coarsening ratio of carbides and γ' precipitates at GBs were significantly higher than that of carbide and γ' precipitates inside the grains; the other is that the coarsening ratio of carbides was markedly higher than that of γ' precipitates. M6C carbide and η phase initially formed in the edge of MC carbide at the expense of MC carbides and γ' precipitates in the vicinity of MC during the early stage of aging. After 3000h, MC carbides inside the grains were covered by η phase films, while those distributed at GBs were completely decomposed into η phase and M6C particles.
24
Li, Shaoying, Xiaojun Xi, Yiwa Luo, Mingtao Mao, Xiao Shi, Jing Guo e Hanjie Guo. "Carbide Precipitation during Tempering and Its Effect on the Wear Loss of a High-Carbon 8 Mass% Cr Tool Steel". Materials 11, n. 12 (7 dicembre 2018): 2491. http://dx.doi.org/10.3390/ma11122491.
Testo completoAbstract (sommario):
In this paper, the precipitation of carbide and wear loss of high-carbon 8 mass% Cr tool steel at two tempering conditions (i.e., 773–803 K and 823–853 K) were studied by INCA Steel, EPMA-1720H, XRD, and ML-10 tester. The results show that the particles of test steels include the carbides (Cr7C3 and Cr23C6) and carbides nucleated on Al2O3. When carbides are of the same size, the number of carbides in test steel at a tempering temperature of 773–803 K is greater than that at a tempering temperature of 823–853 K, especially when the size of carbides is less than 5 μm. Compared with the test steel tempered at 823–853 K, the distance between adjacent actual particles reduced by 80.6 μm and the maximum amount of reduction was 9.4% for single wear loss at the tempering temperature of 773–803 K. It can be concluded from thermodynamics results that Al2O3 inclusions began to precipitate in liquid, and the precipitation of carbides was at the solid–liquid region. Al2O3 can be used as the nucleation interface of carbide, thus promoting the formation of carbides. During the cooling of molten steel, a lower temperature can increase the difference of actual solubility product bigger than equilibrium solubility product, thus promoting the carbide formation.
25
Liu, Bowen, Tian Qin, Wei Xu, Chengchang Jia, Qiuchi Wu, Mingying Chen e Zhe Liu. "Effect of Tempering Conditions on Secondary Hardening of Carbides and Retained Austenite in Spray-Formed M42 High-Speed Steel". Materials 12, n. 22 (11 novembre 2019): 3714. http://dx.doi.org/10.3390/ma12223714.
Testo completoAbstract (sommario):
In this study, the effect of tempering conditions on microstructure, grain size, and carbide phase compositions of spray-formed high-speed steel after quenching at 1180 °C was studied. The influence of carbide phase, size of carbides, and retained austenite content on secondary hardening of the steel was analyzed by field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), electron backscattered diffraction (EBSD), and differential scanning calorimetry (DSC); the hardness, microhardness of carbide, and bending strength were tested. The results show that M3C, M6C, M7C3, and MC carbides may precipitate at different tempering temperatures and the transformation of the retained austenite can be controlled by tempering. The phase composition of carbides, microstructure, and retained austenite content strongly influences the performance characteristics of M42 high-speed steel after tempering. In contrast, the secondary carbides produced by tempering thrice at 540 °C are mainly M6C carbides rich in W and Mo elements, and the content of retained austenite is effectively reduced. At this stage, the Rockwell hardness reaches 67.2 HRC, bending strength reaches 3115 MPa, and the properties and microstructure are optimal.
26
Gogte, Chandrashekhar, Dilip Peshwe e Ravindra Paretkar. "On the Presence of Eta Carbide in the Cryogenically Treated High Speed Steel". Advanced Materials Research 602-604 (dicembre 2012): 356–59. http://dx.doi.org/10.4028/www.scientific.net/amr.602-604.356.
Testo completoAbstract (sommario):
The research in the cryogenic treatment of tool steels and other alloy steels is important as it causes substantial increase in the wear characteristics of alloy and tool steels. The present day research of this technology indicates precipitation of submicroscopic carbides referred to as eta carbides. This work comprises of reviewing the carbide types that form during heat treatment of high speed steels and presenting the results of the experiment for finding eta carbide in the cryogenically treated AISI T42 high speed steels using advanced microscopy. The results of this work indicate the contribution from the other secondary carbides (other than eta carbides) in the enhancement of wear characteristics in high speed steels.
27
Bauer-Grosse, Elizabeth. "Nucleation and Growth of Triangular Prismatic Iron Carbides in Amorphous Films by In Situ Transmission Electron Microscopy". Solid State Phenomena 172-174 (giugno 2011): 959–64. http://dx.doi.org/10.4028/www.scientific.net/ssp.172-174.959.
Testo completoAbstract (sommario):
The crystallization mechanisms of sputtered Fe1-xCx amorphous thin films for three values of atomic carbon content x = 0.28, 0.30 and 0.32 are directly observed using hot stage transmission electron microscopy. Images recorded sequentially are used to track the change caused by heating. Observations concern the nucleation and the growth of iron carbides and their structural identification. Information is also given about their crystallochemistry. They belong to the family of interstitial carbides with carbon atoms located inside iron Triangular Prisms (TP). They are built either from TP Sheets (TPS) stacks deriving from the cementite θ-Fe3C or from TP Chains (TPC) arrangements deriving from the Eckström-Adcock Fe7C3 carbide. The sharp transition between dominant TPS and dominant TPC carbides formations is illustrated. Nucleation and growth processes of both types of carbides are discussed and focus is put on the TPC crystals. They are the first to be formed whatever carbon content of the specimen and really correspond to the dominant phase for the richest-carbon film. When they are less numerous, they can act as nucleation sites for TPS carbides and it is in situ illustrated during the crystallization of the poorest-carbon film where orientation relationships can be found between the TPC-Fe7C3 carbideand a TPS carbide close to the Hägg carbide χ-Fe5C2 The crystallization ofFe0.70C0.30 film corresponds to a particular case where TPC carbides and TPS carbides can coexist with the same composition.
28
Weinberger, Christopher R., e Gregory B. Thompson. "The crystal structure and phase stability of the zeta phase in the group VB transition metal carbides: a computational investigation". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 75, n. 5 (20 settembre 2019): 870–79. http://dx.doi.org/10.1107/s2052520619011302.
Testo completoAbstract (sommario):
The crystal structure and composition of the zeta phase in the group VB transition metal carbides are not completely understood despite decades of experimental studies. As such, the phase rarely appears on phase diagrams of the group VB transition metal carbides. There is currently renewed interest in this phase, as tantalum carbide composites exhibit high fracture toughness in the presence of this phase. This work extends the initial computational study using density functional theory of the phase stability of the zeta phase in the tantalum carbide system, where the tantalum carbide zeta-phase crystal structure and stability were determined, to the niobium and vanadium carbides. It is shown that the zeta phases in the three systems share the same crystal structure and it is an equilibrium phase at low temperatures. The carbon atom ordering in the three different phases is explored and it is demonstrated that the zeta phase in the tantalum carbides prefers to order carbon atoms differently than in the niobium and vanadium carbide zeta phases. Finally, the properties of this crystal are computed, including elastic constants, electronic densities of states and phonon dispersion curves, to illustrate that this crystal structure is similar to other transition metal carbides.
29
Idrees, Maria, Husnain Ahmad Chaudhary, Arslan Akbar, Abdeliazim Mustafa Mohamed e Dina Fathi. "Effect of Silicon Carbide and Tungsten Carbide on Concrete Composite". Materials 15, n. 6 (10 marzo 2022): 2061. http://dx.doi.org/10.3390/ma15062061.
Testo completoAbstract (sommario):
Flexural strength of concrete is an important property, especially for pavements. Concrete with higher flexural strength has fewer cracking and durability issues. Researchers use different materials, including fibers, polymers, and admixtures, to increase the flexural strength of concrete. Silicon carbide and tungsten carbide are some of the hardest materials on earth. In this research, the mechanical properties of carbide concrete composites were investigated. The silicon carbide and tungsten carbide at different percentages (1%, 2%, 3%, and 4%) by weight of cement along with hybrid silicon carbide and tungsten carbide (2% and 4%) were used to produce eleven mixes of concrete composites. The mechanical tests, including a compressive strength test and flexural strength test, along with the rapid chloride permeability test (RCPT), were conducted. It was concluded that mechanical properties were enhanced by increasing the percentages of both individual and hybrid carbides. The compressive strength was increased by 17% using 4% tungsten carbide, while flexural strength was increased by 39% at 4% tungsten carbide. The significant effect of carbides on flexural strength was also corroborated by ANOVA analysis. The improvement in flexural strength makes both carbides desirable for use in concrete pavement. Additionally, the permeability, the leading cause of durability issues, was reduced considerably by using tungsten carbide. It was concluded that both carbides provide promising results by enhancing the mechanical properties of concrete and are compatible with concrete to produce composites.
30
Rakhadilov, B. K., W. Wieleba, М. K. Kylyshkanov, A. B. Kenesbekov e М. Maulet. "Structure and phase composition of high-speed steels". Bulletin of the Karaganda University "Physics Series" 98, n. 2 (30 giugno 2020): 83–92. http://dx.doi.org/10.31489/2020ph2/83-92.
Testo completoAbstract (sommario):
This work is devoted to the study of the structure and phase composition of high-speed steels R6M5, R9 and R18. High service properties of high-speed steel tools are achieved by heat treatment. Therefore, the sample blanks for the study were cut from cutting tools from R6M5, R9 and R18steels, which were subjected tothe usual standard heat treatment for these steels. Installed that the structure of high-speed steels R6M5, R9 and R18 in the initial state, i.e. after standard heat treatment, consists of martensite and special carbides. The carbide particles are evenly distributed in the matrix and are close to the correct spherical shape. Thus in the structure of steels R6M5 and R9 are carbides of type М6С, MC, and in the structure of steel R18 only carbides of the type М6С. EBSD analysis showed that M6C carbides are most optimally combined with the Fe3W3C cubic phase, and the MS type carbide corresponds to the VC phase. Electron microscopic analysis showed that in addition to M6C and MС carbides, high-speed steel contains small amounts of «cementite» type М3С carbides.
31
Zou, De-Ning, e Han-Guang Fu. "Influence of Ce, K, and Na on spheroidization of eutectic carbides in low-tungsten white cast iron". International Journal of Materials Research 96, n. 11 (1 novembre 2005): 1328–31. http://dx.doi.org/10.1515/ijmr-2005-0231.
Testo completoAbstract (sommario):
Abstract Tungsten alloy white cast iron (TAWCI) exhibits strong brittleness and a narrow application scope. The influences of Ce, K and Na on the microstructure and performance of TAWCI have been studied, and the idea to estimate the spheroidization effect of carbides using circular degree (C.D.) is put forward. The results show that eutectic carbides turn from network into sphericity after the modification. Carbide is refined and uniformly distributed and the C.D. of eutectic carbides increases. The mechanism of carbide spheroidization has been analyzed. The impact toughness and wear resistance of TAWCI obviously improves with the rise of C.D. of carbides. The service life of a modified TAWCI roll is 35 % higher than that of high-chromium cast-iron roll, its production cost is reduced by 25 %.
32
Eriksson, Emil, Joel Andersson e Magnus Hörnqvist Colliander. "The Effect of Grain Boundary Carbides on Dynamic Recrystallization During Hot Compression of Ni-Based Superalloy Haynes $$282^{\mathrm{TM}}$$". Metallurgical and Materials Transactions A 53, n. 1 (15 novembre 2021): 29–38. http://dx.doi.org/10.1007/s11661-021-06524-x.
Testo completoAbstract (sommario):
AbstractIn alloys where carbides are the main grain boundary phase, the role of carbides during hot working is not known. Here, we address the effect of grain boundary carbides on the dynamic recrystallization during hot compression of Ni-base superalloy Haynes 282. When excluding variations from experimental factors neither stress evolution nor final microstructure indicated that carbides exerted a significant influence on the dynamic recrystallization. The carbide solvus temperature is not a critical limit during thermomechanical processes.
33
Sun, Fan, D. Mantovani e Frédéric Prima. "Carbides and their Role in Advanced Mechanical Properties of L605 Alloy: Implications for Medical Devices". Materials Science Forum 783-786 (maggio 2014): 1354–59. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.1354.
Testo completoAbstract (sommario):
L605 (ASTM F90), a cobalt-chromium-tungsten alloy with excellent mechanical properties and high radiopacity, has been widely accepted as a suitable alloy for stent applications. The presence of carbides in this alloy, primary carbides and secondary carbides, leads to difficulties in controlling mechanical performances and therefore in optimizing stent size and performances. This work is thus to investigate the carbides and their role in advanced mechanical properties of L605 alloy for stent fabrication. Herein, the nature, nucleation, distribution and dissolution of the carbides were investigated in a series of recrystallized L605 tubes from hard-drawn (HD) state. The mechanical properties corresponding to each carbide state were examined by tensile tests and microhardness measurements. The results indicate important relationships among carbide precipitation, grain size and mechanical behaviors, as a function of annealing temperature and duration. The intergranular secondary carbides, induced at the onset of the recrystallization of L605 matrix, were preferentially precipitated at grain boundaries. The nucleation of such particulate phase leads to a pinning effect on grain coarsening, resulting in a strengthening effect of the material. However, the further growth of the secondary carbides brings about considerable reduction of ductility, which is inacceptable for stent application. Therefore, an optimization protocol on carbides controlling was developed to maintain the strengthening effect without losing ductility and small grain size.
34
Rutkowski, Paweł, Ludosław Stobierski, Mirosław M. Bućko e Bartosz Handke. "Phase, Structural and Microstructural Changes in the TiC1-x – Cr3C2 Materials". Advances in Science and Technology 65 (ottobre 2010): 112–17. http://dx.doi.org/10.4028/www.scientific.net/ast.65.112.
Testo completoAbstract (sommario):
The earlier studies showed that addition of different chromium carbides to nonstoichiometric fine titanium carbide improve sintering in the similar way. The phase, structural and microstructural changes for addition of various chromium carbides were also similar. In the present work the composite materials were made of various carbon quantity saturated titanium carbide (as matrix) and commercial chromium carbide Cr3C2 (as additive). The titanium carbide powders with variable content of carbon in structure were synthesized by the SHS method. The chromium carbide in quantity of 7.5 % by volume was added to the initial mixture. The influence of various stoichiometry of titanium carbide on onset temperature of sintering was examined by use of high temperature dilatometer. The phase and structural changes of examined materials during sintering were made using XRD and Rietveld method. The evolution of microstructure, versus of different stoichiometry titanium carbides, was observed by use of scanning electron microscopy.
35
Lee, J. S., Je Hyun Lee, Baig Gyu Choi, Chang Yong Jo, Ung Yu Paik e S. G. Gang. "The Solidification Microstructure and Carbide Formation Behaviors in the Cobalt-Based Superalloy ECY768". Materials Science Forum 486-487 (giugno 2005): 374–77. http://dx.doi.org/10.4028/www.scientific.net/msf.486-487.374.
Testo completoAbstract (sommario):
Co-base superalloys have been applied in the stationary compoents of gas turbine owing to their excellent high temperaure properties. The stationary Co-base alloy components are generally manufactured by casting. Solidification behavior of the alloy is an important factor in the selection of casting parameters. In the present study, solidification microstructure and carbide formation behaviors were studied by directional solidification. Directional solidification experiments were carried out at the solidification rates of 0.5 ~ 150µm/s with the Co-base superalloy ECY768. Between the dendrites just below the final freezing temperature, MC carbide and M23C6 carbide were found. It was identified that the script or blocky carbides were Ta or W-rich MC carbide, and the lamellar carbides were Cr-rich M23C6 eutectic carbides. The solid/liquid interface morphology clearly showed that freezing of the Cr-rich eutectic carbide occurred just after the script type MC carbide.
36
Rhyim, Young Mok, Sang Ho Han, Young Sang Na e Jong Hoon Lee. "Effect of Deep Cryogenic Treatment on Carbide Precipitation and Mechanical Properties of Tool Steel". Solid State Phenomena 118 (dicembre 2006): 9–14. http://dx.doi.org/10.4028/www.scientific.net/ssp.118.9.
Testo completoAbstract (sommario):
It is well known that the durability of tool steel could be improved by deep cryogenic treatment. It has been assumed that the increase of service life of tool steel caused by decrease of retained austenite and/or by formation of nano-scale fine η-carbide. But the principles of deep cryogenic treatment remain unclear yet. In this research, to manifest the effect of deep cryogenic treatment on wear resistance, the specimen was emerged in liquid nitrogen for 20 hours for deep cryogenic treatment after austenitizing and the following tempering temperature was varied. The microstructure of specimens was observed using TEM and the mechanical properties and wear resistance were examined. As the tempering temperature increased, the carbides became larger and fine carbides were formed above certain temperature. In the case of deep cryogenic treated specimen, the number of carbides increased while the carbides size was decreased, furthermore, the fine carbide forming temperature was lowered also. It was considered that the deep cryogenic treatment increased the driving force for the nucleation of carbides. As tempering temperature increased, hardness decreased while wear resistance and impact energy increased. The deep cryogenic treated specimens showed this tendency more clearly. It was considered that the wear resistance is affected not only to the hardness but also to the precipitation of fine carbides, and this carbide evolution can be optimized through the deep cryogenic treatment.
37
Zhang, Yongjie, Goro Miyamoto e Tadashi Furuhara. "Atom Probe Compositional Analysis of Interphase Precipitated Nano-Sized Alloy Carbide in Multiple Microalloyed Low-Carbon Steels". Microscopy and Microanalysis 25, n. 2 (12 novembre 2018): 447–53. http://dx.doi.org/10.1017/s1431927618015374.
Testo completoAbstract (sommario):
AbstractThe composition of nano-sized alloy carbides formed by interphase precipitation in V–Nb and V–Ti multiple microalloyed low-carbon steels is analyzed by using three-dimensional atom probe. Carbide-forming alloying elements including V, Nb, and Ti, are simultaneously precipitated from the early stage of isothermal treatment, whose atoms are uniformly distributed in the carbide particles, even after prolonged holding. Cluster analysis by the maximum separation method, with parameters optimized using different methods, is carried out to extract alloy carbides from matrix. The composition of alloy carbides evaluated by site fraction of substitutional carbide-forming alloying elements indicates that at the early stage of their formation, Nb and Ti are more strongly enriched than V.
38
Novák, Pavel, Kateřina Nová, Lucyna Jaworska e Andrei Shishkin. "Identification of Carbides in Tool Steel by Selective Etching". Defect and Diffusion Forum 395 (agosto 2019): 55–63. http://dx.doi.org/10.4028/www.scientific.net/ddf.395.55.
Testo completoAbstract (sommario):
This paper describes simple metallographic technique for selective etching of individual types of carbides (MC, M2C and M6C and M7C3) in tool steel. Electrolytic etching in chromic acid was used in order to reveal the MC carbides. Chemical etching in permanganate solution revealed the M2C and M6C carbides, while the electrolytic etching in the latter solution enabled to observe M7C3, M2C and M6C carbides. These techniques were demonstrated on an experimental niobium-containing tool steel prepared by powder metallurgy. The results confirm that the MC carbides are highly thermally stable, while the M2C carbides decompose during austenitizing at the temperature of 1050 °C and higher. The M7C3 carbides dissolve in the austenite significantly. This exact and simple observation of the carbides behaviour enables to describe the role of particular carbides on heat treatment behaviour and also to save the carbide-forming elements, where the important ones (tungsten, vanadium) are listed as critical raw materials and the others (chromium and molybdenum) are also strategic.
39
Funakawa, Yoshimasa. "Mechanical Properties of Ultra Fine Particle Dispersion Strengthened Ferritic Steel". Materials Science Forum 706-709 (gennaio 2012): 2096–100. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.2096.
Testo completoAbstract (sommario):
The influence of carbides diameter on the mechanical properties of the ferritic steel that was strengthened by the interface precipitated carbides in rows was investigated. Low carbon steel containing titanium as much as carbon in atomic concentration was induction-melt and hot-rolled, followed by the soaking at some temperatures to obtain completely transformed ferrite in which fine carbides precipitated. Lowering holding temperature resulted in fine carbide generation and reduction of the row spacing. Yield strength significantly increased with the decrease in the carbide diameter. The amount of the particle dispersion strengthening was close to the calculation result according to Ashby-Orowan Mechanism. On the other hand, elongation slowly decreased. The decrease in elongation is caused by the reduction of the uniform-elongation. Local elongation did not change by the change of the diameter of the fine carbides in the matrix since voids in the specimen were generated not besides fine carbides but beside large TiN during tensile test.
40
Öztürk, Kubilay, Alptekin Kısasöz, Gökhan Özer e Ahmet Karaaslan. "Precipitation of carbides in a nickel-based cast heat-resistant alloy during thermal exposure: evolution of microstructure, hardness and corrosion properties". Materials Testing 65, n. 2 (1 febbraio 2023): 233–43. http://dx.doi.org/10.1515/mt-2022-0243.
Testo completoAbstract (sommario):
Abstract Ni-based G-NiCr28W alloy, which is widely preferred in high-temperature applications, has an austenite matrix as well as carbides dispersed in the structure. The morphology of the carbides in the structure varies depending on the chemical composition and heat treatment. Carbide phases commonly seen in these alloys are MC, M7C3, and M23C6. These carbides can transform into each other and the mechanical properties of the alloy can be affected by the carbide transformation. In this study, the effects of the carbides on the morphology, distribution, and strength of the alloy were investigated following the solution treatment applied at different temperatures and durations. Samples were characterized by light metal microscopy, SEM, EDS, XRD analysis, hardness, and potentiodynamic polarization tests. After the process, due to the excess of more stable carbides and their homogeneous distribution within the structure, the highest hardness and corrosion values were revealed in the sample that was processed at 1000 °C for 100 h.
41
Wang, Hongwei, Lei Wang, Yang Liu e Xiu Song. "Improving Intermediate Temperature Plasticity of Co–Al–W–Base Superalloy: Based on Optimizing MC Carbides". Metals 13, n. 2 (15 febbraio 2023): 402. http://dx.doi.org/10.3390/met13020402.
Testo completoAbstract (sommario):
The brittleness of the new Co–Al–W–base superalloys is said to be a fatal weakness for their application in the intermediate temperature range, especially for polycrystal Co–Al–W–base superalloys. MC carbide controlling is used to improve the intermediate temperature plasticity of the Co–Al–W–base superalloy in the present study. Both microstructure characterization and interrupted tensile tests were performed to investigate the mechanism of improving the plasticity of the superalloy by MC carbides at an intermediate temperature of 800 °C. The results show that the plasticity of the superalloy is mainly dependent on MC carbides. MC carbide breakers appear after yielding, which closely depends on the morphology and size of MC carbides. Based on the experimental and calculation results, it is found that the intermediate temperature plasticity of the superalloy can be guaranteed by controlling the critical mean size of MC carbides, and the desired mean size of MC carbides should be less than 47 μm.
42
Gaqi, Yila, Kenta Kusumoto, Kazumichi Shimizu e Riki Hendra Purba. "Effect of Carbide Orientation on Wear Characteristics of High-Alloy Wear-Resistant Cast Irons". Lubricants 11, n. 7 (22 giugno 2023): 272. http://dx.doi.org/10.3390/lubricants11070272.
Testo completoAbstract (sommario):
Both erosive and abrasive wear are common in mechanical systems and moving components in industrial production. Once they occur in machine parts, the task of breakdown maintenance should be carried out, leading to high production costs. Previous research has shown that high-chromium cast iron (HCCI), a commonly used wear-resistant material, experiences repeated particle impacts that break up the chromium carbides (M7C3) on its surface, resulting in the formation of fine fracture carbides. It has been reported that erosion wear occurs progressively due to the shedding of protrusions caused by the plastic deformation of the material’s matrix. Thus, the erosion wear characteristics of a material are strongly affected by carbides, which come in various shapes and can affect resistance. This research examined the orientation of carbides on the microstructure and their effects on erosion and abrasion properties. The wear tests showed that 27 wt.% chromium content high-alloy cast irons showed the best wear resistance properties due to the coarse strips of M7C3 carbides that effectively suppressed wear propagation. Additionally, the M2C carbides crystallized around the M7C3 carbides which support the M7C3 carbide to reduce plastic deformation and carbide peel-out. Consequently, the wear resistance properties of this material are significantly improved.
43
Wu, Yan, Zhi Wei Zhang, Qian Wang, Na Xiao e Xiang Zhao. "Effect of Magnetic Field Strength on Carbide Precipitation Behavior in W6Mo5Cr4V3 High Speed Steel during Medium Temperature Tempering". Key Engineering Materials 709 (settembre 2016): 15–18. http://dx.doi.org/10.4028/www.scientific.net/kem.709.15.
Testo completoAbstract (sommario):
Effect of magnetic field strength on carbide precipitation behavior in W6Mo5Cr4V3 highspeed steel during medium temperature tempering was investigated. The applied magnetic field promoted the precipitation and refinement of M6C and MC carbides at boundaries and in the grain interior, but maximum spheroidization occurred for those M6C carbides precipitated at boundaries, the stronger the magnetic field strength, the stronger the spheroidization effect. The high magnetic field hinders the precipitation of M2C type carbides, and the M2C type carbides basically disappear when applying the magnetic field.
44
Krutskii, Yu L., T. S. Gudyma, T. M. Krutskaya, А. О. Semenov e A. V. Utkin. "Carbides of transition metals: Properties, application and production. Review. Part 2. Chromium and zirconium carbides". Izvestiya. Ferrous Metallurgy 66, n. 4 (19 agosto 2023): 445–58. http://dx.doi.org/10.17073/0368-0797-2023-4-445-458.
Testo completoAbstract (sommario):
The properties, application, and methods for producing chromium and zirconium carbides are considered. These carbides are oxygen-free refractory metal-like compounds. As a result, they are characterized by high values of thermal and electrical conductivity. Their hardness is relatively high. Chromium and zirconium carbides exhibit significant chemical resistance in aggressive environments. For these reasons, they have found application in modern technology. Chromium carbide is used mainly as component of surfacing mixtures to create protective coatings that resist intensive abrasive wear, including at elevated temperatures (up to 800 °C) in oxidizing environments. This compound is also used in the manufacture of tungsten-free hard alloys and carbide steels. Chromium carbide, along with vanadium carbide, is used as a grain growth inhibitor in WC – Co hard alloys. Powdered zirconium carbide can be used to polish the surface of items made of ferrous and non-ferrous metals. The properties of refractory compounds depend on the content of impurities and dispersion (particle size). To solve a specific problem associated with the use of refractory compounds, it is important to choose the right method for their preparation, to determine the permissible content of impurities in the initial components. This leads to the existence of different methods for the synthesis of carbides. The main methods for their preparation are: synthesis from simple substances (metals and carbon), metallothermal and carbothermal reduction. Plasma-chemical synthesis (vapor-gas phase deposition) is also used to obtain carbide nanopowders. A characteristic is given to each of these methods. Information on the possible mechanism of the processes of carbothermal synthesis is presented.
45
Vereschaka, A. A., A. S. Vereschaka e A. I. Anikeev. "Carbide Tools with Nano-Dispersed Coating for High-Performance Cutting of Hard-to-Cut Materials". Advanced Materials Research 871 (dicembre 2013): 164–70. http://dx.doi.org/10.4028/www.scientific.net/amr.871.164.
Testo completoAbstract (sommario):
The problem of increasing performance of carbide too lin machining hard-to-machine materials has been studied. Composite material was developed comprising carbide with heat-resistant bond Co-Re, significantly increasing resistance of carbide to thermoplastic deformation, and nanodispersed multilayer composite coating, significantly reducing thermomechanical impact on cutting part of tool.Studies to find the performance of tool made of developed composite material in turning hardened steel40H and heat-resistant nickel alloy HN77TYUR have shown its superiority compared to commercial carbides with coatings of modern generation.Studies have found out practicability of using VRK-13 cobalt-rhenium carbides with reduced content of expensive rhenium from 9% (weight) Re to 6% (weight), and it is highly competitive by heat resistance with VRK-15 carbide and is significantly superior to it by its strength.Results of cutting properties research forultra-dispersed Re-added WC-Co-carbides with Ti-TiN-TiCrAlNnano-dispersed multilayer composite coating are presented at longitudinal turning of constructional steels and hard-to-machine alloys. It is shown that the combination of ultra-dispersedheat-resistant WC-(Co,Re)-carbides and wear-resistant Ti-TiN-TiCrAlN coatings increase cutting properties of tool in some times.
46
Zhang, Xiao Jing, Yong Qing Ma, Yu Fen Liang e Guo Fang Liu. "Influence of the Mo and V Contents on Microstructure and Secondary Hardening of 6Cr6W2MoV Steel". Advanced Materials Research 936 (giugno 2014): 1267–72. http://dx.doi.org/10.4028/www.scientific.net/amr.936.1267.
Testo completoAbstract (sommario):
The influence of Mo and V contents on the microstructure and secondary hardening of 6Cr6W2MoV steel was studied in this paper, and the process factors and the transformation mechanism of the influence results were discussed by phase equilibrium thermodynamic analysis. The results show that, the microstructure of 6Cr6W2MoV steel is uniform and thin, in which the undissolved carbide size after quenching is 0.23μm. In the heating and cooling process of the annealing, the dissolution and precipitation of M23C6↔M6C carbides transformation can be used to carbides distributing uniform refinement. Adding an overmany Mo content will lead to coarsening of carbide particles due to small amplitude of M23C6↔M6C transformation. Adding an overmany V content will appear a small of the bulk MC carbide on the crystallization, so the heterogeneity of carbides is increasing. The tempering hardness of 6Cr6W2MoV steel is 63.5HRC, and when adding an overmany Mo content the maximal hardness arrives to 65HRC. Adding Mo changes the carbide composing, it is conducive to the variety of carbides precipitation strengthening near intermediate temperature and the tempering hardness increasing. When adding an overmany V content the more MC carbide well occupy more amount of C, the tempering temperature dispersion increases too, so the tempering hardness debases deservedly and the highest hardness only reaches HRC60.5.
47
Cai, Hang Wei, Hong Guan Wu, Zhi Kang Ma, Cheng Lei Wang, Lin Yuan, Wei Zhang, Bing Li e Yuan Gao. "Research on the Carbides of Its Alloying Layer Conducted by W-Mo-Y Surface Alloying and Carburizing Process". Advanced Materials Research 472-475 (febbraio 2012): 2891–95. http://dx.doi.org/10.4028/www.scientific.net/amr.472-475.2891.
Testo completoAbstract (sommario):
Q235 steel was processed by solid carburizing and quenching after conducted by W-Mo-Y double glow-discharge plasma surface alloying process. Finally carbon contents, the morphologies and phases of the samples' surface were analyzed. The results show as follows: Carbon contents of the samples' surface are 1.28 wt%, 1.36 wt%, 1.51 wt% respectively after W-Mo-Y alloying layer (also called co-penetrated layer) was processed by solid carburizing at 960 °C, 980 °C, 1020 °C respectively; The amount of the carbides in W-Mo-Y alloying layer is obviously more than that of the carbides in W-Mo alloying layer; The granular carbides distribute dispersively and uniformly in alloying layer, and the sizes of carbide particle are less than 1 μm; There is no eutectic carbide at the grain boundaries; With temperatures of carburizing and quenching process rising, the carbides increases in number; After W-Mo-Y alloying layer was carburized and quenched at 1020 °C, the phases of alloying layer are Fe2C, W2C, Fe2MoC, MoC, Fe3C, Mo2C and Y2C3; and the types of their carbides are M3C, M2C, and MC, which are different from the types of W-Mo carbides in general metallurgy high-speed steel (HSS). It can be seen from the available, the morphologies, the sizes and the amount of surface HSS's carbides can be adjusted by heat treatment.
48
Hu, Qipeng, Miaohui Wang, Yunbo Chen, Hailong Liu e Zhen Si. "The Effect of MC-Type Carbides on the Microstructure and Wear Behavior of S390 High-Speed Steel Produced via Spark Plasma Sintering". Metals 12, n. 12 (16 dicembre 2022): 2168. http://dx.doi.org/10.3390/met12122168.
Testo completoAbstract (sommario):
The microstructure and wear behavior of S390 high-speed steel (HSS) reinforced with different volume fractions of MC-type carbides produced via spark plasma sintering were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) in this study. SEM and TEM results show that V-W-rich carbides are formed around the added MC-type carbides, and these carbides have a similar composition to the M(C, N) carbides precipitated at high temperatures according to thermodynamic calculations. Both macrohardness and three-point bending results show that the carbide type is the dominant factor increasing the hardness, and the volume fraction of the carbide is the dominant factor leading to a decrease in the three-point bending strength. The wear mechanism of HSS metal matrix composites (MMCs) is confirmed as abrasive wear and oxidative wear via wear tracks and oxidation films. Compared with the sample without reinforcement (85 HRA, wear coefficient of 1.50 × 10−15 m2/N), the best MT-3 sample exhibits a hardness increase of 1.8 HRA and a three-fold increase in wear resistance.
49
Kopyciński, D., E. Guzik e A. Szczęsny. "Equiaxed and Oriented Microstructure in High Chromium Cast Iron". Archives of Metallurgy and Materials 59, n. 2 (1 giugno 2014): 723–26. http://dx.doi.org/10.2478/amm-2014-0119.
Testo completoAbstract (sommario):
Abstract It has been proved that an addition of boron carbide and shredded steel scrap introduced as an inoculants to the chromium white cast iron changes the microstructure of castings. The operation increases the number of crystallization nuclei of M7C3 carbides. In this case the B4C carbides act as substrates for the nucleation of M7C3 (chromium carbides). Castings after B4C inoculation have fine grain fracture surface. Primary precipitates of chromium carbide also appeared, lowering the mechanical properties of as-cast parts. Additionally, in order to increase the mechanical properties of chromium cast iron, unidirectional solidification was used. In this case, 0.3 wt. % cerium was used as inoculant.
50
Faye, Omar, e Jerzy A. Szpunar. "Effect of Metal Carbides on Hydrogen Embrittlement: A Density Functional Theory Study". Hydrogen 5, n. 1 (20 marzo 2024): 137–48. http://dx.doi.org/10.3390/hydrogen5010009.
Testo completoAbstract (sommario):
This study uses plane wave density functional theory (DFT) to investigate the effect of certain metal carbides (Niobium carbide, Vanadium carbide, Titanium carbide, and Manganese sulfide) on hydrogen embrittlement in pipeline steels. Our results predict that the interaction of hydrogen molecules with these metal carbides occurs in the long range with binding energy varying in the energy window [0.043 eV to 0.70 eV].In addition, our study shows the desorption of H2 molecules from these metal carbides in the chemisorptions. Since atomic state hydrogen interacts with NbC, VC, TiC, and MnS to cause embrittlement, we classified the strength of the hydrogen trapping as TiC + H > VC + H > NbC + H> MnS + H. In addition, our study reveals that the carbon site is a more favorable hydrogen-trapping site than the metal one.