Journal articles: 'Ni-Mn-Ga System'

1

Ma, Yunqing, Shuiyuan Yang, Yan Zhou, Cuiping Wang, and Xingjun Liu. "A new ternary compound (Ni, Mn)2Ga in Ni–Mn–Ga system." Intermetallics 18, no. 11 (November 2010): 2105–8. http://dx.doi.org/10.1016/j.intermet.2010.06.017.

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Mahendran, Manickam, Jorge Feuchtwanger, and Robert C. O'Handley. "Acoustic Energy Absorption in Ferromagnetic Ni-Mn-Ga Shape Memory Alloy Polymer Composites." Advanced Materials Research 52 (June 2008): 87–94. http://dx.doi.org/10.4028/www.scientific.net/amr.52.87.

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The single crystal Ni-Mn-Ga and Ni-Mn-Ga particulate composites have responded to mechanical stress up to 1 kHz frequencies with significant acoustic attenuation. It has been observed that in Ni-Mn-Ga polymer composites, a heavy static load on both the ends of the system increases the acoustic stress amplitude and appears to have acoustic loss drops. The attenuation, as a function of frequency shows resonances in the displacement of the vibrating particle indicating the twin boundary motions. It is inferred that the resonances beyond the principal mode are highly damped in the Ni-Mn-Ga composite samples.

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Gupta, K. P. "The Ga-Mn-Ni (Gallium-Manganese-Nickel) System." Journal of Phase Equilibria and Diffusion 29, no. 1 (August 23, 2007): 101–9. http://dx.doi.org/10.1007/s11669-007-9017-x.

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Ma, Yun Qing, Shui Yuan Yang, Ryosuke Kainuma, Kiyohito Ishida, Cui Ping Wang, and Xing Jun Liu. "Experimental Investigations of the High-Temperature Phase Relationship and Ordering Transition in Ni-Mn-Ga Ternary System." Advanced Materials Research 148-149 (October 2010): 1695–700. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.1695.

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The phase equilibria at 900 °C and B2/L21 order-disorder transition in the Ni-Mn-Ga ternary system were investigated by analyzing the equilibrated alloys and diffusion couples using a combination of techniques. It was confirmed that a bcc single phase region exists in a wide composition range at 900 °C, and the critical temperatures of B2/L21 order-disorder transition were determined in Ni-50 at.% section, which exhibits a maximal ordering transition temperature of 796 at Mn content of 25 at.%. The obtained results will be helpful for the preparation and annealing of Ni-Mn-Ga alloys in the specific temperature.

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Mahalakshmi, Chelliah, Racil Jeya Geetha, Shanmugam Vinodh Kumar, Sonai Seenithurai, and Manickam Mahendran. "Attenuation of dilatational wave in ferromagnetic shape memory alloy polyurethane polymer composites." Journal of Composite Materials 51, no. 19 (November 13, 2016): 2727–32. http://dx.doi.org/10.1177/0021998316677848.

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The ferromagnetic shape memory alloy polyurethane, Ni-Mn-Ga-PU, polymer composites absorb more mechanical energy than the conventional materials used for vibration damping applications. The vibration damping has been investigated using the custom-made experimental setup. The computed resonance peak values are in agreement with the experimental data. The dilatational wave decreases at high frequencies which is consistent with the theory of resonance frequency. The previously free end of the system increases the amplitude stress for an appreciable static load but loss appears to be very small. The 20% ferromagnetic shape memory alloy in polyurethane absorbs much more energy than the pure polyurethane due to the movement of twin boundaries present in Ni-Mn-Ga. The Ni-Mn-Ga-PU polymer composites of this nature can be a suitable candidate for acoustic attenuation applications.

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Chernenko, V. A., V. V. Kokorin, O. M. Babii, and I. K. Zasimchuk. "Phase diagrams in the NiMnGa system under compression." Intermetallics 6, no. 1 (January 1998): 29–34. http://dx.doi.org/10.1016/s0966-9795(97)00050-2.

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Jiang, Lei, Yanbo Dong, and Zhen Cui. "Adsorption of Metal Atoms on SiC Monolayer." Inorganics 11, no. 6 (May 30, 2023): 240. http://dx.doi.org/10.3390/inorganics11060240.

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The electronic, magnetic, and optical behaviors of metals (M = Ag, Al, Au, Bi, Ca, Co, Cr, Cu, Fe, Ga, K, Li, Mn, Na, Ni) adsorbed on the SiC monolayer have been calculated based on density functional theory (DFT). The binding energy results show that all the M-adsorbed SiC systems are stable. All the M-adsorbed SiC systems are magnetic with magnetic moments of 1.00 μB (Ag), 1.00 μB (Al), 1.00 μB (Au), 1.01 μB (Bi), 1.95 μB (Ca), 1.00 μB (Co), 4.26 μB (Cr), 1.00 μB (Cu), 2.00 μB (Fe), 1.00 μB (Ga), 0.99 μB (K), 1.00 μB (Li), 3.00 μB (Mn), and 1.00 μB (Na), respectively, except for the Ni-adsorbed SiC system. The Ag, Al, Au, Cr, Cu, Fe, Ga, Mn, and Na-adsorbed SiC systems become magnetic semiconductors, while Bi, Ca, Co, K, and Li-adsorbed SiC systems become semimetals. The Bader charge results show that there is a charge transfer between the metal atom and the SiC monolayer. The work function of the K-adsorbed SiC system is 2.43 eV, which is 47.9% lower than that of pristine SiC and can be used in electron-emitter devices. The Bi, Ca, Ga, and Mn-adsorbed SiC systems show new absorption peaks in the visible light range. These results indicate that M-adsorbed SiC systems have potential applications in the field of spintronic devices and solar energy conversion photovoltaic devices.

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Chernenko, Volodymyr A., O. Babii, Victor A. L'vov, and Paul G. McCormick. "Martensitic Transformations in Ni-Mn-Ga System Affected by External Fields." Materials Science Forum 327-328 (January 2000): 485–88. http://dx.doi.org/10.4028/www.scientific.net/msf.327-328.485.

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Wedel, C., and K. Itagaki. "High-temperature phase relations in the ternary Ga-Mn-Ni system." Journal of Phase Equilibria 22, no. 3 (May 2001): 324–30. http://dx.doi.org/10.1361/105497101770338833.

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Sokolovskaya, Yulia, Olga Miroshkina, Danil Baigutlin, Vladimir Sokolovskiy, Mikhail Zagrebin, Vasilly Buchelnikov, and Alexey T. Zayak. "A Ternary Map of Ni–Mn–Ga Heusler Alloys from Ab Initio Calculations." Metals 11, no. 6 (June 17, 2021): 973. http://dx.doi.org/10.3390/met11060973.

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In the search for new magnetic functional materials, non-stoichiometric compounds remain a relatively unexplored territory. While experimentalists create new compositions looking for improved functional properties, their work is not guided by systematic theoretical predictions. Being designed for perfect periodic crystals, the majority of first-principles approaches struggle with the concept of a non-stoichiometric system. In this work, we attempt a systematic computational study of magnetic and structural properties of Ni–Mn–Ga, mapped onto ternary composition diagrams. Compositional stability was examined using the convex hull analysis. We show that the cubic austenite has its stability region close to the stoichiometric Ni2MnGa, in agreement with experimental data, while the tetragonal martensite spreads its stability over a wider range of Mn and Ni contents. The unstable compositions in both austenite and martensite states are located in the Ga-rich corner of the ternary diagram. We note that simultaneous stability of the austenite and martensite should be considered for potentially stable compounds suitable for synthesis. The majority of compounds are predicted to be ferrimagnetically ordered in both austenitic and martensitic states. The methodology used in this work is computationally tractable, yet it delivers some predictive power. For experimentalists who plan to synthesize stable Ni–Mn–Ga compounds with ferromagnetic order, we narrow the target compositional range substantially.

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Chernenko, Volodymyr A., and Victor A. L'vov. "Magnetoelastic Nature of Ferromagnetic Shape Memory Effect." Materials Science Forum 583 (May 2008): 1–20. http://dx.doi.org/10.4028/www.scientific.net/msf.583.1.

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The giant magnetically-induced deformation of ferromagnetic shape memory alloys results from the magnetic field-induced rearrangement of twinned martensite under the magnetic field. This deformation is conventionally referred to as the magnetic-field-induced-strain (MFIS). The MFIS is comparable in value with the spontaneous deformation of crystal lattice during the martensitic transformation of an alloy. Although the first observations of MFIS were reported more than 30 years ago, it has got a world-wide interest 20 years later after the creation of the Ni–Mn–Ga alloy system with its practically important room-temperature martensitic structure and experimental evidence of the large magnetostriction. The underlying physics as well as necessary and sufficient conditions for the observation of MFIS are the main focus of this chapter. A magnetostrictive mechanism of the unusual magnetic and magnetomechanical effects observed in Ni–Mn–Ga alloys is substantiated and a framework of consistent theory of these effects is outlined starting from the fundamental conception of magnetoelasticity and the commonly known principles of ferromagnetism and linear elasticity theories. A reasonable agreement between the theoretical deductions and available experimental data is demonstrated and, in this way, a key role of magnetoelastic coupling in the magnetomechanical behavior of Ni–Mn–Ga alloys is proved. A correspondence of magnetostrictive mechanism to the crystallographic features of MFIS and the basic relationships of the thermodynamics of solids are discussed.

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Wang, Yu, Chonghui Huang, Jinghui Gao, Sen Yang, Xiangdong Ding, Xiaoping Song, and Xiaobing Ren. "Evidence for ferromagnetic strain glass in Ni-Co-Mn-Ga Heusler alloy system." Applied Physics Letters 101, no. 10 (September 3, 2012): 101913. http://dx.doi.org/10.1063/1.4751250.

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13

Chernenko, V. A., E. Cesari, V. V. Kokorin, and I. N. Vitenko. "The development of new ferromagnetic shape memory alloys in Ni-Mn-Ga system." Scripta Metallurgica et Materialia 33, no. 8 (October 1995): 1239–44. http://dx.doi.org/10.1016/0956-716x(95)00370-b.

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14

Seguí, Concepcio, Joan Torrens-Serra, Eduard Cesari, and Patricia Lázpita. "Optimizing the Caloric Properties of Cu-Doped Ni–Mn–Ga Alloys." Materials 13, no. 2 (January 16, 2020): 419. http://dx.doi.org/10.3390/ma13020419.

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With the purpose to optimize the functional properties of Heusler alloys for their use in solid-state refrigeration, the characteristics of the martensitic and magnetic transitions undergone by Ni50Mn25−xGa25Cux (x = 3–11) alloys have been studied. The results reveal that, for a Cu content of x = 5.5–7.5, a magnetostructural transition between paramagnetic austenite and ferromagnetic martensite takes place. In such a case, magnetic field and stress act in the same sense, lowering the critical combined fields to induce the transformation; moreover, magnetocaloric and elastocaloric effects are both direct, suggesting the use of combined fields to improve the overall refrigeration capacity of the alloy. Within this range of compositions, the measured transformation entropy is increased owing to the magnetic contribution to entropy, showing a maximum at composition x = 6, in which the magnetization jump at the transformation is the largest of the set. At the same time, the temperature hysteresis of the transformation displays a minimum at x = 6, attributed to the optimal lattice compatibility between austenite and martensite. We show that, among this system, the optimal caloric performance is found for the x = 6 composition, which displays high isothermal entropy changes (−36 J·kg−1·K−1 under 5 T and −8.5 J·kg−1·K−1 under 50 MPa), suitable working temperature (300 K), and low thermal hysteresis (3 K).

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15

Kostromitin, K. I., Vasiliy D. Buchelnikov, V. V. Sokolovskiy, and P. Entel. "Theoretical Study of Twin Boundary Motion in Heusler Ni-Mn-Ga Alloys Using Monte Carlo Method." Solid State Phenomena 190 (June 2012): 327–30. http://dx.doi.org/10.4028/www.scientific.net/ssp.190.327.

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The twin boundary motion in Ni-Mn-Ga Heusler alloys has been investigated using Monte Carlo simulations. The Hamiltonian of system includes magnetic and elastic parts and two magnetoelastic terms. It is shown that the twin boundary shifts in a magnetic field at the constant temperature. The spin and strain volume fractions have been obtained at different temperatures.

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16

Yang, Shuiyuan, Cuiping Wang, and Xingjun Liu. "Phase equilibria and composition dependence of martensitic transformation in Ni–Mn–Ga ternary system." Intermetallics 25 (June 2012): 101–8. http://dx.doi.org/10.1016/j.intermet.2011.12.009.

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17

BHATTACHARYA, JAYEE, VIJAY SINGH, SURAJIT SENGUPTA, and INDRA DASGUPTA. "MAGNETO-STRUCTURAL TRANSITIONS: MOLECULAR DYNAMICS SIMULATIONS OF A UNITED-ATOM, MESOSCOPIC MODEL." Modern Physics Letters B 27, no. 07 (March 19, 2013): 1350047. http://dx.doi.org/10.1142/s0217984913500474.

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In this paper, we perform hybrid Langevin and molecular dynamics simulations on a two-dimensional, united-atom, mesoscopic model to obtain the phase diagram for a solid undergoing a magneto-structural transition. The interatomic exchange interactions are inspired by ab initio calculations in the Ni 2 MnGa system. The spins are updated with the help of Langevin soft spin dynamics. The nature of the phase diagram obtained from our simulations is similar to that obtained experimentally in Ni 2+x Mn 1-x Ga Heusler alloys showing magnetic and martensitic transitions with excess Ni stoichiometry viz. x.

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Cristea, Gabriela, Adriana Dehelean, Romulus Puscas, Florina-Dorina Covaciu, Ariana Raluca Hategan, Csilla Müller Molnár, and Dana Alina Magdas. "Characterization and Differentiation of Wild and Cultivated Berries Based on Isotopic and Elemental Profiles." Applied Sciences 13, no. 5 (February 25, 2023): 2980. http://dx.doi.org/10.3390/app13052980.

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The isotopic content (δ13C, δ2H, δ18O) and concentrations of 30 elements (Li, Na, Mg, P, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, Ag, Cd, Ba, Pb, La, Ce, Pr, Nd, Sm, Eu, Gd, and Tb) were determined in different wild and cultivated berries (raspberry, seaberry, blackberry, cranberry, and blueberry). Partial least squares discriminant analysis (PLS-DA) was applied in order to develop models for differentiating berries according to their botanical origin and growing system. δ13C, δ2H, δ18O, Li, Na, Mg, P, Ca, V, Mn, Co, Ni, Zn, As, Rb, Sr, Ba, and Eu were identified as significant elements for the differentiation of berry species, based on which an 85% PLS-DA model accuracy was obtained. Similarly, the PLS-DA model developed for the growing system differentiation correctly classified 94.4% of the cultivated berries and 77.2% of the wild ones, based on the main predictors: δ13C, δ18O, Li, Na, Ca, Cr, Mn, Ni, Rb, and Ba. The developed PLS-DA model for the discrimination of wild blueberries from cultivated ones showed excellent levels of sensitivity (100%), specificity (100%), and accuracy (100%).

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Okamoto, Nariaki, Takashi Fukuda, Tomoyuki Kakeshita, and Tetsuya Takeuchi. "Magnetocrystalline Anisotropy and Twinning Stress of 10M and 2M Martensites in Ni-Mn-Ga System." Materials Science Forum 512 (April 2006): 195–200. http://dx.doi.org/10.4028/www.scientific.net/msf.512.195.

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Ni2MnGa alloy with 10M martensite exhibits rearrangement of martensite variants (RMV) by magnetic field, but Ni2.14Mn0.92Ga0.94 with 2M martensite does not. In order to explain the difference, we measured uniaxial magnetocrystalline anisotropy constant Ku and the stress required for twinning plane movement τreq in these alloys. Concerning the former alloy, the maximum value of magnetic shear stress acting across twinning plane τmag, which is evaluated as |Ku| divided by twinning shear, becomes larger than τr eq. On the other hand, concerning the latter alloy, the maximum of τmag is only one-tenth of τreq at any temperature examined. Obviously, the relation, τmag> τr eq, is satisfied when RMV occurs by magnetic field and vice versa. In this martensite, the large twinning shear of 2M martensite is responsible for small τmag and large τreq.

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Mehrer, Helmut, and Sergiy V. Divinski. "Diffusion in Metallic Elements and Intermetallics." Defect and Diffusion Forum 289-292 (April 2009): 15–38. http://dx.doi.org/10.4028/www.scientific.net/ddf.289-292.15.

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Starting from some fundamentals of solid-state diffusion, we remind the reader to the major techniques for lattice diffusion measurements. Self-diffusion is the most basic diffusion phenomenon in any solid. The paper covers main features of self-diffusion in pure fcc and bcc metals and some important facts about diffusion of substitutional solutes in metals. Binary intermetallics are compounds of two metals or of a metal and a semimetal. Their structures are different from those of the constituents. Some intermetallics are interesting functional materials others have attracted attention as high-temperature structural materials. The paper reviews some results mainly from our laboratory on diffusion in binary intermetallics from the systems Cu-Zn, Ni-Al, Fe-Al, Ni-Ge, Ni-Ga, Fe-Si, Ti-Al, Ni-Mn, Mo-Si and Co-Nb, which have been published in detail elsewhere. Some results for the ternary system Ni-Fe-Al are also mentioned.

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Locmelis, Marek, Ricardo D. Arevalo, Igor S. Puchtel, Marco L. Fiorentini, and Euan G. Nisbet. "Transition metals in komatiitic olivine: Proxies for mantle composition, redox conditions, and sulfide mineralization potential." American Mineralogist 104, no. 8 (August 1, 2019): 1143–55. http://dx.doi.org/10.2138/am-2019-6914.

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AbstractWe present the results of a comprehensive study on the concentrations of first-row transition elements (FRTE: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn), as well as Ga and Ge, in liquidus olivine from 2.7–3.5 Ga old Al-undepleted and Al-depleted komatiites from the Kaapvaal and Zimbabwe Cratons in southern Africa, the Yilgarn Craton in Australia, and the Superior Craton in Canada. The sample set includes komatiites that remained sulfur-undersaturated upon emplacement, as well as komatiites that reached sulfide saturation owing to assimilation of crustal sulfur.All olivine grains display concentrations of Mn, Zn, Ge, Co, Fe, Mg, and Ni similar to the Bulk Silicate Earth (BSE) values, with significant negative anomalies in Sc, Ti, V, Cr, Ga, and Cu. Olivine from the studied Al-depleted komatiites displays on average higher 100×Ga/Sc ratios (>5) than olivine from Al-undepleted komatiites (≤5). Because garnet preferentially incorporates Sc over Ga, the data suggest that elevated Ga/Sc ratios in komatiitic olivine are indicative of garnet retention in the source region of komatiites, highlighting the potential of olivine trace element chemistry as a proxy for the depth of komatiite melting and separation of the magma from the melting residue. Copper concentrations in the studied olivine grains are controlled by sulfur saturation of the host komatiite during olivine crystallization. Olivine from sulfur-undersaturated komatiite systems displays Cu concentrations mostly between 1 and 10 ppm, whereas olivine from sulfide-bearing komatiites has Cu contents of <0.5 ppm. Because komatiites contain some of the world's highest metal tenor magmatic Ni-Cu sulfide deposits, the Cu variability in olivine as a function of the sulfide-saturation state highlights a potential application of olivine chemistry in the exploration for sulfide ore deposits.Olivine from the Paleo-Archean (3.5–3.3 Ga) komatiites displays overall higher V/Sc ratios (V/Sc = 2.1 ± 0.96; 2 S.D.) than olivine from their Neo-Archean (2.7 Ga) counterparts (V/Sc = 1.0 ± 0.81, 2 S.D.). Vanadium and Sc behave similarly during partial melting of the mantle and are similarly compatible in majorite garnet. However, V is redox-sensitive and its compatibility in olivine increases as the system becomes less oxidized, whereas Sc is redox-insensitive. We argue that olivine from the studied Paleo-Archean komatiites crystallized from more reduced magmas than their Neo-Archean counterparts. Elevated Fe/Mn ratios in olivine from Paleo-Archean komatiites mimic the V/Sc signatures and are interpreted to reflect that Fe2+ is more compatible in olivine than Fe3+. These results imply that V/Sc and Fe/Mn in komatiitic olivine may potentially provide insight into the evolution of the oxidation state of the Archean mantle. Additional studies that integrate the chemistry of komatiitic olivine with those of relict interstitial glass and melt/fluid inclusions are encouraged to fully understand and quantify the potential of FRTE in olivine as a proxy for the oxidation state of the mantle sources of komatiite magmas.

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Sun, Guo-Tao, and Jia-Xi Zhou. "Application of Machine Learning Algorithms to Classification of Pb–Zn Deposit Types Using LA–ICP–MS Data of Sphalerite." Minerals 12, no. 10 (October 14, 2022): 1293. http://dx.doi.org/10.3390/min12101293.

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Pb–Zn deposits supply a significant proportion of critical metals, such as In, Ga, Ge, and Co. Due to the growing demand for critical metals, it is urgent to clarify the different types of Pb–Zn deposits to improve exploration. The trace element concentrations of sphalerite can be used to classify the types of Pb–Zn deposits. However, it is difficult to assess the multivariable system through simple data analysis directly. Here, we collected more than 2200 analyses with 14 elements (Mn, Fe, Co, Ni, Cu, Ga, Ge, Ag, Cd, In, Sn, Sb, Pb, and Bi) from 65 deposits, including 48 analyses from carbonate replacement (CR), 684 analyses from distal magmatic-hydrothermal (DMH), 197 analyses from epithermal, 456 analyses from Mississippi Valley-type (MVT), 199 analyses from sedimentary exhalative (SEDEX), 377 analyses from skarn, and 322 analyses from volcanogenic massive sulfide (VMS) types of Pb–Zn deposits. The critical metals in different types of deposits are summarized. Machine learning algorithms, namely, decision tree (DT), K-nearest neighbors (KNN), naive Bayes (NB), random forest (RF), and support vector machine (SVM), are applied to process and explore the classification. Learning curves show that the DT and RF classifiers are the most suitable for classification. Testing of the DT and RF classifier yielded accuracies of 91.2% and 95.4%, respectively. In the DT classifier, the feature importances of trace elements suggest that Ni (0.22), Mn (0.17), Cd (0.13), Co (0.11), and Fe (0.09) are significant for classification. Furthermore, the visual DT graph shows that the Mn contents of sphalerite allow the division of the seven classes into three groups: (1) depleted in Mn, including MVT and CR types; (2) enriched in Mn, including epithermal, skarn, SEDEX, and VMS deposits; and (3) DMH deposits, which have variable Mn contents. Data mining also reveals that VMS and skarn deposits have distinct Co and Ni contents and that SEDEX and DMH deposits have different Ni and Ge contents. The optimal DT and RF classifiers are deployed at Streamlit cloud workspace. Researchers can select DT or RF classifier and input trace element data of sphalerite to classify the Pb–Zn deposit type.

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Калашников, В. С., И. И. Мусабиров, В. В. Коледов, В. А. Андреев, Д. В. Гундеров, and В. Г. Шавров. "Функциональная усталость сплавов с эффектом памяти формы систем Ni-Mn-Ga и Ni-Ti в условиях термоциклирования под постоянной нагрузкой." Журнал технической физики 90, no. 4 (2020): 603. http://dx.doi.org/10.21883/jtf.2020.04.49084.110-19.

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A comparative study of the functional properties and functional fatigue of Ni-Mn-Ga alloys in the initial cast state and Ni-Ti alloys in the initial hot-forged state without heat treatment was carried out. Measurements were carried out using experimental technique of three-point bending of samples in the form of plates of ~ 0.7 mm x 10 mm x 1.5 mm. It is shown that Ni2MnGa alloy in the cast state is preferably used for lightly loaded actuators (up to 100 MPa) and reversible deformations (up to 1.5%) in the temperature range from -85 C to -75 C; Ni-Ti system alloy in hot-forged state is recommended for highly loaded actuators (up to 500 MPa) , high reversible deformations (up to 8.5%) in the temperature range from -40 C to 40 C.

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Mehrer, Helmut. "Self-Diffusion, Solute-Diffusion and Interdiffusion in Binary Intermetallics." Diffusion Foundations 2 (September 2014): 1–72. http://dx.doi.org/10.4028/www.scientific.net/df.2.1.

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800x600 Intermetallics are compounds of two metals or of metal(s) and semimetal(s). Their structures are usually different from those of the constituents. Some intermetallics are interesting functional materials, others have attracted attention as high-temperature structural materials. We remind the reader of some fundamentals of solid-state diffusion and to the major techniques for tracer diffusion measurements, interdiffusion studies and the growth kinetics of layers in solid diffusion couples. Starting from self-diffusion, which is the most basic diffusion phenomenon in any solid, the paper covers the main features of diffusion in binary intermetallics from the systems Cu-Zn, Ni-Al, Fe-Al, Mg-Al, Ni-Ge, Ni-Ga, Fe-Si, Ti-Al, Ni-Mn, Mo-Si, Co-Nb and Ni-Nb.. We illustrate the influence of phase transitions on diffusion and point out some common features of diffusion in intermetallics. We discuss in detail diffusion in silicides of iron, molybdenum and of silicides of refractory metals. We also consider aluminides of iron, nickel, and titanium and in the aluminium-magnesium system. We consider diffusion in intermetallics of the cobalt-niobium and nickel-niobium system and in in the Nb-Sn and V-Ga systems. We finish with some remarks about grain boundary diffusion in intermetallics. Normal 0 21 false false false UK X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";}

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Ustinov, A., L. Olikhovska, N. Glavatska, and I. Glavatskyy. "Diffraction features due to ordered distribution of twin boundaries in orthorhombic Ni–Mn–Ga crystals." Journal of Applied Crystallography 42, no. 2 (March 14, 2009): 211–16. http://dx.doi.org/10.1107/s0021889809007171.

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The diffraction intensity distributions for orthorhombic crystals containing the ordered twin boundaries of the system (110), 〈1{\overline 1}0〉 were calculated in the kinematic approach using the Monte Carlo computer simulation technique. A simple model of short-range order in the arrangement of the twin boundaries was assumed to generate the nano-twinned structure. Analysis of the intensity distributions showed that such a twin boundary distribution results in the formation of extra peaks along the reciprocal lattice rods that are perpendicular to the close-packed planes. These extra peak intensities and positions are dependent on the most probable distances between the twin boundaries and on the degree of short-range order.

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Chiu, Wan-Ting, Pimpet Sratong-on, Masaki Tahara, Volodymyr Chernenko, and Hideki Hosoda. "Large magnetostrains of Ni-Mn-Ga/silicone composite containing system of oriented 5M and 7M martensitic particles." Scripta Materialia 207 (January 2022): 114265. http://dx.doi.org/10.1016/j.scriptamat.2021.114265.

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Gao, Q., H. Zhang, R. Yang, Z. Fan, Y. Liu, J. Wang, X. Geng, et al. "Effect of alloying elements on the stacking fault energies of dilute al-based alloys." Journal of Mining and Metallurgy, Section B: Metallurgy 54, no. 2 (2018): 185–96. http://dx.doi.org/10.2298/jmmb180107007g.

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A systematic study of the stacking fault energy (?SF) for the dilute Al-based alloys (Al23X, Al47X and Al71X, where X = Al, Ag, Be, Ca, Cd, Co, Cu, Cr, Fe, Ga, Ge, Hf, In, K, La, Li, Mn, Mg, Ni, Na, Pb, Sc, Sn, Sr, Si, Ti, V, Zn, and Zr) has been performed by means of first-principles calculations. Alias shear deformation is adopted in the present investigations. The presently calculated ?SF for Al is in favorable accordance with experimental and other theoretical data. For the targeted elements, the calculations indicate that Na, Si, K, Ca, Sc, Ga, Ge, Sr, Zr, In, Sn, La, Hf, and Pb, in any concentration we considered, decrease the ?SF of Al, while Ag, Be, Cd, Co, Cu, Cr, Fe, Li, Mn, Mg, Ni, Ti, V, and Zn increase the ?SF of Al, when the concentration of alloying elements is 1.39 at. % in the system. With increasing concentration of alloying elements, Li, Mg, V, Ti, and Cd change from increasing the ?SF of Al to decreasing it, based on present investigations. Among the alloying elements, which decrease the ?SF of Al, La decreases the ?SF most significantly. It is also found that the ?SF of Al-X generally decreases with the increase of equilibrium volume. The results obtained in the present work provide an insight into the design of Al based alloys.

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Dobrzański, Zbigniew, Katarzyna Chojnacka, Tadeusz Trziszka, Sebastian Opaliński, Łukasz Bobak, Damian Konkol, and Mariusz Korczyński. "The Effect of Dietary Humic Preparations on the Content of Essential and Non-Essential Chemical Elements in Hen Eggs." Animals 10, no. 8 (July 23, 2020): 1252. http://dx.doi.org/10.3390/ani10081252.

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This study was conducted to determine the effect of dietary supplementation with two humic preparations, Humokarbowit (HKW) and Humobentofet (HBF), on the mineral content of the albumen and egg yolk of Lohmann Brown hens. The content of macroelements (Ca, K, Mg, Na, P, S), microelements (Al, Ba, Cu, Fe, I, Mn, Si, Sr, Zn) and trace elements (Ag, As, Be, Bi, Cd, Co, Cr, Ga, Hg, Li, Mo, Ni, Pb, Rb, Sb, Se, Sn, Ti, Tl, V, W, Y and Zr) in the feed mixture (FM), albumen and yolk were presented. The material was collected from laying hens kept in a cage system in two groups, control (C) and enriched (E), with standard feed and feed enriched with humic preparations, respectively. The enriched feed mixture was characterised by a significantly higher Ag, Ba, Be, Bi, Co, Fe, Ga, Hg, K, Mg, Ni, S, Sb, Si, Zn and Zr content compared to the standard, basal mixture. Only some of these elements were found in significantly increased levels in albumen (Bi, Co, Ni, S) and yolk (Bi, Fe, K, Sb). Another noteworthy finding was a significantly lower concentration of Na in the content of eggs from the E-Group, which corresponds to the content of this important macronutrient in the feed. In addition, a significant increase in the concentration of elements such as Al, I, Li, Sr, Ti, Tl, Y, W was noted with a reduction in Cd, Cr, Hg, Mn, Rb, Sn in Group-E, which indicates a complicated egg formation processes, including biotransfer-essential and non-essential chemical elements.

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Stepanova, V. A., and N. P. Mironycheva-Tokareva. "Lateral and radial geochemical structure of bog catena soils (on the example of middle-taiga bog system of Western Siberia)." IOP Conference Series: Earth and Environmental Science 928, no. 1 (December 1, 2021): 012012. http://dx.doi.org/10.1088/1755-1315/928/1/012012.

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Abstract Lateral and radial geochemical structure of bog catena soils of Western Siberia middle-taiga subzone has been investigated on the base of B, Na, Mg, Al, P, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, Y, Zr, Mo, Cd, Sb, Cs, Ba, Hf, W, Pb, Th, U and lanthanoides content. Bog catena is characterized with high contrast of radial distribution of most studied elements. Lateral differentiation is significantly lower than radial one and is monotonous for most elements. In bog catena soils of Western Siberia middle-taiga subzone there are investigated correlations between elements content and soils characteristics that are mainly determined by specific peculiarities of ecosystem development.

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Zhou, Xuezhi, Wei Li, H. P. Kunkel, and Gwyn Williams. "A criterion for enhancing the giant magnetocaloric effect: (Ni–Mn–Ga)—a promising new system for magnetic refrigeration." Journal of Physics: Condensed Matter 16, no. 6 (January 30, 2004): L39—L44. http://dx.doi.org/10.1088/0953-8984/16/6/l02.

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Yang, Tonghan, Wei He, Guojian Chen, Weijing Zeng, Jinzhi Wang, Lingmin Zeng, and Jianlie Liang. "The Phase Relations of the Co-Ni-In Ternary System at 673 K and 873 K and Magnetic Properties of Their Compounds." Materials 13, no. 18 (September 9, 2020): 3990. http://dx.doi.org/10.3390/ma13183990.

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The phase relationships of the ternary Co-Ni-In system at 673 K and 873 K were investigated by means of powder X-ray diffraction, scanning electron microscopy equipped with energy dispersive spectroscopy, and optical microscopy. Though CoIn2 does not exist at 873 K, the ternary solid solution Co1−xNixIn2 exists at both 673 K and 873 K with different composition ranges. The Rietveld refinements were carried out to investigate the crystal structure of Co1−xNixIn2 (x = 0.540, and 0.580) and Ni2−xCoxIn3 (x = 0.200). The magnetization dependence of temperature (MT) curves of Ni2−xCoxIn3 (x = 0.200) and Co1−xNixIn2 (x = 0.540) are similar to those of the ferromagnetic shape memory alloys Ni-Mn-A (A = Ga, Sn, and In), but do not undergo martensitic transformation. The maximum magnetic entropy changes in Ni2−xCoxIn3 (x = 0.200) and Co1−xNixIn2 (x = 0.540) under 3T are 1.25 and 1.475 J kg−1K−1, respectively.

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McLeod, Michael V., Bhaskar S. Majumdar, and Zafer Turgut. "Magnetocaloric Improvements in Doped Heusler Alloys." MRS Advances 2, no. 56 (2017): 3453–58. http://dx.doi.org/10.1557/adv.2017.372.

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ABSTRACTMagnetocaloric materials have gained significant interest as an environment friendly and efficient refrigeration technology. We have been working on Heusler alloys, primarily the Ni-Mn-Ga system for improved magnetocaloric effect (MCE). We have observed significant MCE increase in stress assisted thermally cycled samples and demonstrated that one primary mechanism is texture change. More recently, we have observed volumetric decrease as well as anisotropy changes due to stressed cycling. The influence of these parameters on magnetic anisotropy and MCE are discussed. We have also utilized isoelectronic Al substitution at the Ga lattice sites for optimizing atomic distances and exchange interactions in an effort to bring about magnetostructural transformation closer to room temperature (RT) while retaining high MCE. The results show that Al substitutions can bring about large decreases (50 – 70K) in both the Curie (TC) and martensite start (Ms) temperatures, and permit fine tuning the magnetostructural transformation temperature.

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Srivastava, Saurabh Kumar, Vijay Kumar Srivastava, Anupam Joshi, Pawel Kamasa, Lajos Károly Varga, V. V. Khovaylo, and Ratnamala Chatterjee. "A low temperature anomaly observed in off-stoichiometric Ni–Mn–Ga system studied by higher harmonic ac-susceptibility measurements." Applied Physics Letters 97, no. 12 (September 20, 2010): 122505. http://dx.doi.org/10.1063/1.3486155.

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Suñol, Joan Josep, J. Saurina, Rastislav Varga, B. Hernando, José Luis Sánchez Llamazares, J. D. Santos, and V. M. Prida. "Structural and Magnetic Transitions in Rapidly Solidified Heusler Alloys Ribbons." Solid State Phenomena 150 (January 2009): 143–57. http://dx.doi.org/10.4028/www.scientific.net/ssp.150.143.

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The most extensively studied Heusler alloys are those based on the Ni-Mn-Ga system. However, to overcome the high cost of Gallium and the usually low martensitic transformation temperature, the search for Ga-free alloys has been recently attempted, particularly, by introducing In, Sn or Sb. In this work, Mn50Ni40In10, Mn50Ni34In16, Ni50Mn36-xIn14+x (x = 0, 0.5, 1, 1.5) and Ni50Mn37Sn13 ribbons has been obtained by melt spinning. We outline their structural and thermomagnetic behavior. Columnar grains and preferential orientation has been obtained. The martensitic, Tm, and the Curie, TC, temperatures of the ribbons are lower than those of the bulk samples with similar compositions. This effect is probably due to the ribbons small and constrained grains. For it, a large under-cooling is necessary for the martensitic transformation. The decrease of TC in the ribbons could be associated with the increased degree of quenched-in short-range disorder around defects.

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Jain, Deepti, Soma Banik, L. S. Sharath Chandra, S. R. Barman, R. Nath, and V. Ganesan. "Domain Structures across the Martensitic Transformation in Ni_2+xMn_1-xGa." Materials Science Forum 635 (December 2009): 69–74. http://dx.doi.org/10.4028/www.scientific.net/msf.635.69.

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Evolution of domain structures across the martensitic transition (Tm) in the ferromagnetic shape memory alloy system Ni-Mn-Ga is studied using an optical microscope with a temperature variation. Compositions chosen have Tm < Tc, Tm = Tc and Tm > Tc, (Tc=Curie temperature) so that one can compare the nature of martensitic domains. There are no appreciable domain structures when Tm < Tc as compared to the one with Tm > Tc. However, giant morphological changes in the form of appearance of well-developed domains that are propagating with different directions are seen for the composition in which Tm=Tc. The results are discussed in the light of Magnetic Force Microscopy observations as well as giant entropy changes known to occur on samples with co-occurrence of Tm and Tc.

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Zhou, Xuezhi, Wei Li, H. P. Kunkel, and Gwyn Williams. "Influence of the nature of the magnetic phase transition on the associated magnetocaloric effect in the Ni–Mn–Ga system." Journal of Magnetism and Magnetic Materials 293, no. 3 (June 2005): 854–62. http://dx.doi.org/10.1016/j.jmmm.2004.12.004.

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Карпенков, Алексей Юрьевич, Павел Андреевич Ракунов, Ирек Ильфирович Мусабиров, and Галина Григорьевна Дунаева. "INFLUENCE OF DEFORMATION PROCESSING ON MAGNETOCALORIC EFFECT OF HEUSLER ALLOYS." Physical and Chemical Aspects of the Study of Clusters, Nanostructures and Nanomaterials, no. 14 (December 15, 2022): 149–58. http://dx.doi.org/10.26456/pcascnn/2022.14.149.

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В настоящей работе представлены результаты комплексных исследований влияния деформации, полученной методом всесторонней изотермической ковки, на магнитокалорические свойства сплава Гейслера на основе Ni-Mn-Ga. Прямые измерения адиабатического изменения температуры показали, что в результате циклирования образца в магнитном поле μΔH-1,85Тл, ΔT(T) может уменьшаться на величину, соответствующую необратимому изменению температуры на этапе первого цикла намагничивания, связанному с выделением срытой теплоты перехода. Пренебрежение этим эффектом приводит к завышенной оценке магнитокалорического эффекта материалов с переходом первого рода. Анализ влияния деформационной обработки на температуры фазовых превращений и величину магнитокалорического эффекта указывает на то, что применение всесторонней изотермической ковки к исходному составу привело к незначительному уменьшению намагниченности, а следовательно и величины магнитокалорического эффекта, а также смещению температуры фазового перехода в сторону низких температур и уменьшение ширины температурного гистерезиса на температурных зависимостях магнитных свойств, измеренных в процессе нагревания и охлаждения образца. This paper presents the results of complex studies of the effect of deformation obtained by the multiple isothermal forging method on the magnetocaloric properties of the Ni-Mn-Ga Heusler alloy system. Direct measurements of the adiabatic temperature change show that cycling the sample in a magnetic field μΔH-1,85T can decrease the maximum of ΔT(T) by the value corresponding to the latent heat of transition. Neglecting this transformation effect leads to an overestimation of the magnetocaloric effect of materials with the first-order transition. An analysis of the deformation treatment effect on the phase transformation temperatures and the magnitude of the magnetocaloric effect indicates that the application of multiple isothermal forging leads to a small decrease of the magnetization and the magnitude of the magnetocaloric effect. Deformation also causes a shift in the phase transition temperature towards low temperatures and decrease of the temperature hysteresis width.

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Dilmieva, E. T., A. P. Sivachenko, A. V. Golovchan, A. I. Ivanova, R. M. Grechishkin, A. D. Zigert, and V. G. Shavrov. "Technology for synthesis of single crystals of Heusler alloys of Ni-Mn-Ga family for applicationin cascade magnetocaloric cooling system 5." Челябинский физико-математический журнал 5, no. 4-2 (2020): 525–36. http://dx.doi.org/10.47475/2500-0101-2020-15412.

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Musabirov, I. I., I. M. Safarov, I. Z. Sharipov, M. I. Nagimov, V. V. Koledov, V. V. Khovailo, and R. R. Mulyukov. "Effect of upsetting deformation temperature on the formation of the fine-grained cast alloy structure of the Ni–Mn–Ga system." Physics of the Solid State 59, no. 8 (August 2017): 1570–76. http://dx.doi.org/10.1134/s1063783417080170.

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Ohtsuka, Makoto, Christina Wedel, and Kimio Itagaki. "Phase Relations in the Ni–Mn–Ga Ternary System and Aging Effect on Shape Memory Properties of Ferromagnetic Ni2MnGa Sputtered Films." Monatshefte für Chemie - Chemical Monthly 136, no. 11 (November 2005): 1909–14. http://dx.doi.org/10.1007/s00706-005-0382-z.

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Song, Y., R. Yang, D. Li, W. T. Wu, and Z. X. Guo. "First principles study of influence of alloying elements on TiAl: Lattice distortion." Journal of Materials Research 14, no. 7 (July 1999): 2824–29. http://dx.doi.org/10.1557/jmr.1999.0377.

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The influence of ternary additions Cr, Fe, Mn, Ni, Zr, Nb, Mo, Hf, Ta, Si, Ga, Ge, In, and Sb, as well as the anti-site defects of both Ti and Al, on lattice parameters of TiAl were studied by the first principles electronic structure calculations with a discrete variational cluster method. The results of the calculation show that the effect of ternary additions on the distortion of TiAl lattice varies with the substitution behavior of the individual alloying element involved. The addition of alloying elements in TiAl causes a change in the electronic structure and the density of states of the system and results in variation of the bond strength between the atoms. The total and partial density of states (DOS) of binary TiAl and of ternary TiAl–M, M = Cr, Zr, and Sb, etc., were comparatively examined. The relationship between the DOS and the bond strength is discussed. The present work suggests that the origin of the lattice distortion of the ternary TiAl–M systems lies in the variation of the electronic structure.

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Yi, Liu Zhi, and J. Kanski. "Superconducting and electronic properties of the metallic glass system La75Si25?x M x (M=Cr, Mn, Fe, Co, Ni, Cu, B, Al, Ga, In)." Zeitschrift f�r Physik B Condensed Matter 73, no. 4 (December 1989): 495–99. http://dx.doi.org/10.1007/bf01319378.

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43

Takhsha Ghahfarokhi, Milad, Lucia Nasi, Francesca Casoli, Simone Fabbrici, Giovanna Trevisi, Riccardo Cabassi, and Franca Albertini. "Following the Martensitic Configuration Footprints in the Transition Route of Ni-Mn-Ga Magnetic Shape Memory Films: Insight into the Role of Twin Boundaries and Interfaces." Materials 13, no. 9 (May 1, 2020): 2103. http://dx.doi.org/10.3390/ma13092103.

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Magnetic shape memory Heuslers have a great potential for their exploitation in next-generation cooling devices and actuating systems, due to their “giant” caloric and thermo/magnetomechanical effects arising from the combination of magnetic order and a martensitic transition. Thermal hysteresis, broad transition range, and twinning stress are among the major obstacles preventing the full exploitation of these materials in applications. Using Ni-Mn-Ga seven-modulated epitaxial thin films as a model system, we investigated the possible links between the phase transition and the details of the twin variants configuration in the martensitic phase. We explored the crystallographic relations between the martensitic variants from the atomic-scale to the micro-scale through high-resolution techniques and combined this information with the direct observation of the evolution of martensitic twin variants vs. temperature. Based on our multiscale investigation, we propose a route for the martensitic phase transition, in which the interfaces between different colonies of twins play the major role of initiators for both the forward and reverse phase transition. Linking the martensitic transition to the martensitic configuration sheds light onto the possible mechanisms influencing the transition and paves the way towards microstructure engineering for the full exploitation of shape memory Heuslers in different applications.

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Silva Campos, Maria del Rosario, Carsten Blawert, Nico Scharnagl, Michael Störmer, and Mikhail L. Zheludkevich. "Cathodic Protection of Mild Steel Using Aluminium-Based Alloys." Materials 15, no. 4 (February 10, 2022): 1301. http://dx.doi.org/10.3390/ma15041301.

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Typically, steel is protected from corrosion by employing sacrificial anodes or coatings based on Zn, Mg, Al or Cd. However, stricter environmental regulations require new environmentally friendly alternatives to replace Cd. Traditionally, Al-based anodes have been employed to cathodically protect steel in marine applications or as ion vapour deposition (IVD)-Al sacrificial coatings for aerospace applications. However, Al tends to passivate, thus losing its protective effect. Therefore, it is important to identify possible alloys that can provide a constantly sufficient current. In this study, Al-X alloys (X = Ag, Bi, Ca, Cr, Cu, Ga, Gd, In, Mg, Mn, Ni, Sb, Si, Sn, V, Ti, Zn and Zr) were firstly tested for a screening of the sacrificial properties of binary systems. Al-0.5Cr, Al-1Sn, Al-0.2Ga, Al-0.1In, Al-2Si and Al-5Zn alloys were suggested as promising sacrificial Al-based alloys. Suitable heat treatments for each system were implemented to reduce the influence of the secondary phases on the corrosion properties by minimising localised attack. extensive evaluation of the corrosion properties, including galvanic coupling of these alloys to steel, was performed in the NaCl electrolyte. A comparative analysis was conducted in order to choose the most promising alloy(s) for avoiding the passivation of Al and for efficient cathodic protection to steel.

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Tischendorf, G., H. J. Förster, and B. Gottesmann. "Minor- and trace-element composition of trioctahedral micas: a review." Mineralogical Magazine 65, no. 2 (April 2001): 249–76. http://dx.doi.org/10.1180/002646101550244.

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AbstractMore than 19,000 analytical data mainly from the literature were used to study statistically the distribution patterns of F and the oxides of minor and trace elements (Ti, Sn, Sc, V, Cr, Ga, Mn, Co, Ni, Zn, Sr, Ba, Rb, Cs) in trioctahedral micas of the system phlogopite-annite/siderophyllite-polylithionite (PASP), which is divided here into seven varieties, whose compositional ranges are defined by the parametermgli(= octahedral Mg minus Li). Plots of trace-element contentsvs.mglireveal that the elements form distinct groups according to the configuration of their distribution patterns. Substitution of most of these elements was established as a function ofmgli. Micas incorporate the elements in different abundances of up to four orders of magnitude between the concentration highs and lows in micas of ‘normal’ composition. Only Zn, Sr and Sc are poorly correlated tomgli. In compositional extremes, some elements (Zn, Mn, Ba, Sr, Cs, Rb) may be enriched by up to 2–3 orders of magnitude relative to their mean abundance in the respective mica variety. Mica/melt partition coefficients calculated for Variscan granites of the German Erzgebirge demonstrate that trace-element partitioning is strongly dependent on the position of the mica in the PASP system, which has to be considered in petrogenetic modelling.This review indicates that for a number of trace elements, the concentration ranges are poorly known for some of the mica varieties, as they are for particular host rocks (i.e. igneous rocks of A-type affiliation). The study should help to develop optimal analytical strategies and to provide a tool to distinguish between micas of ‘normal’ and ‘abnormal’ trace-element composition.

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Zeiner, Michaela, Monika Šoltić, Ivan Nemet, and Iva Juranović Cindrić. "Multielement Determination in Turmeric (Curcuma longa L.) Using Different Digestion Methods." Molecules 27, no. 23 (December 1, 2022): 8392. http://dx.doi.org/10.3390/molecules27238392.

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The antioxidant, anti-inflammatory and antiseptic properties of turmeric (Curcuma longa L.) derive from its rich nutritional composition making it interesting for medicinal uses, besides being used as spice in cooking. To complete the picture on the composition of turmeric, not only the organic compounds need to be known, but also the elemental composition covering essential and potentially toxic elements. The samples were digested in a microwave assisted digestion system using different reagent mixtures. The best digestion mixture was semi-concentrated nitric acid combined with hydrogen peroxide. After optimization of the sample preparation method, the contents of Ag, Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Rb, Se, Sr, Te, Tl, V and Zn in curcuma were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), as well as by inductively coupled plasma mass spectrometry (ICP-MS). Even if the general composition found is in line with the scarce data in literature, clear differences can be seen between the analyzed samples, considering provenience, production procedures, and harvesting year as potential influencing factors. Whereas all samples contained less As and Pb than regulated by WHO, one limit exceeding was found for Cd.

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Kushima, Takuro, Koichi Tsuchiya, Yasuyoshi Sho, Takafumi Yamada, Yoshikazu Todaka, and Minoru Umemoto. "Phase Transformation and Microstructures in Ni and Cu Base Ferromagnetic Shape Memory Alloys." Materials Science Forum 539-543 (March 2007): 3157–62. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.3157.

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Effect of chemical composition was investigated on martensitic transformation temperatures, Curie temperature, magnetization and microstructures for Ni-(Mn, Fe, Co)-Ga and Cu-Mn-Ga systems. In the Ni-(Mn, Fe, Co)-Ga alloys, which is a modification of Ni-Mn-Ga systems, the Af and TC over 400 K were achieved. Cu-Mn-Ga alloy exhibited shape memory effect at temperatures above 373 K and had TC over 400 K. Furthermore, Cu-Mn-Ga exhibits good ductility even in polycrystalline condition unlike the case of Ni-Mn-Ga. Effect of addition of the fourth element to improve the magnetic property is under investigation.

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Boak, Jeremy, Tengfei Wu, and Justin Birdwell. "Geochemical studies of the Green River Formation in the Piceance Basin, Colorado." Geosites 50 (September 1, 2022): 1–32. http://dx.doi.org/10.31711/ugap.v50i.114.

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The Eocene Green River Formation contains the largest oil shale deposits in the world and is a welldocumented example of a lacustrine depositional system. In addition, mineral resources associated with oil shale in the Piceance Basin nahcolite [NaHCO3] and dawsonite [NaAl(CO3)(OH)2)] are of current and potential economic value, respectively. Detailed geochemical analysis across the basin can aid in the understanding of the depositional environment, sedimentary processes, and water-chemistry evolution in this system. Quantitative geochemical data for Green River oil shale from the Piceance Basin of Colorado were collected by inductively coupled plasma optical emission spectroscopy and mass spectrometry as part of this study. The basin margin is represented by samples from exposures at Douglas Pass (Garfield County) and the basin center area is characterized by core samples from two drilled wells: the Shell 23X-2 and John Savage 24-1 (Rio Blanco County). Major elements and groups of elements are used as proxies for clastic influx (Si, Al, K, Ti), carbonate deposition (Ca, Mg), salinity (Na), paleo-productivity (P), and redox state (Fe, S), respectively. Minor and trace elements reinforce observations based on major elements, including Rb, Zr, Nb for clastic influx and Mn, Sr for carbonate. Trace elements are used to characterize redox conditions (As, Mo, U, V, Co, Ni, Cu, Zn) and salinity (Rb/K, B/Ga). Chemical distinctions between the basin margin and the basin center, in terms of these components and total organic carbon concentrations, support the model of a permanently stratified lake through most of the depositional interval. A primary purpose of the study was to conduct more extensive sampling to confirm conclusions of a previous reconnaissance study. Geochemical data from this study indicates elevated Na around the basin margin occurring earlier than in the deeper basin. Early in the history of Lake Uinta, the salinity may have been elevated first in the shallower marginal waters, due to increased evaporation, which then led to elevated salinity in the basin center through transport of saline density currents. Other indicators of salinity (Rb/K, B/Ga) do not track Na content in intervals where clay minerals are absent due to diagenetic alteration under hypersaline conditions but may be used to indicate the salinities at which authigenic Na-bearing minerals begin to form. Most Na-rich samples show high proportions of clastic constituents (Si, Al, K, Ti) compared to conventional carbonate constituents (Ca, Mg). Redox-sensitive period IV transition metal elements (V, Co, Ni, Cu, Zn) show only local occurrence of significant enrichment relative to average shale abundances. Analysis of Fe/Al ratios for this dataset suggests that the depletion of these elements may be related to source rocks depleted in mafic constituents, with apparent redox-related enrichments subdued by this effect. The basin margin samples reflect generally oxic bottom waters, with some intervals deposited under more reducing, possibly dysoxic to anoxic conditions. The basin center results indicate more reducing conditions, with Mo and U enrichment factors suggesting operation of a particulate shuttle mechanism that scavenged Mo on Fe/Mn-oxyhydroxides that redissolved at depth, with Mo precipitating along with sulfides and/or organic matter at or near the sediment/water interface.

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Hu, Hao, and Kari Ullakko. "Selective Etch for Micromachining Process in Manufacturing Hybrid Microdevices composed of Ni-Mn-Ga and Silicon Layers." Solid State Phenomena 344 (June 6, 2023): 81–88. http://dx.doi.org/10.4028/p-132l12.

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The goal of this study is to make selective etch possible for the next generation of MEMS(microelectromechanical systems) devices that are composed Ni-Mn-Ga and silicon layers. Due tothe large magnetic-field-induced strains of Ni-Mn-Ga, sensing and actuating components can be fab-ricated in the Ni-Mn-Ga layers. Other functional components can be manufactured in the silicon layer.Single crystalline Ni-Mn-Ga alloys that are grown by using the Bridgman vertical growth techniquehave so far obtained the largest magnetic field-induced strain (MFIS), a magnetic shape memory(MSM) effect. Similar to silicon wafers, Ni-Mn-Ga wafers are also sliced from crystal-oriented singlecrystalline ingots. To fabricate hybrid MEMS devices such as micromanipulators and robots, lab-on-chip containing micropump manifolds and valves, or vibration energy harvesters, the fabricationprocesses used for MEMS devices will be also used to fabricate components in the Ni-Mn-Ga layer ofthe hybrid MEMS devices. One of the most important processes for MEMS fabrication is the structur-ing of materials by chemical etching. The main goal of this study is to obtain evidence that the etchantetches silicon but not Ni-Mn-Ga and to identify an etchant that etches Ni-Mn-Ga but not silicon. Thepresent paper reports on a novel experiment in dissolving Ni-Mn-Ga alloys. An etchant compositionof 69% HNO3, 98% H2SO4, and CuSO4•5H2O is proposed for dissolving Ni-Mn-Ga alloys and thevariation in the dissolution rate by adjusting the concentrations of HNO3 and ultrapure water (UPW)is demonstrated. This etchant was demonstrated to etch Ni-Mn-Ga but not silicon. The HF+HNO3acidic solution commonly used for etching silicon does not dissolve Ni-Mn-Ga alloys.

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Colás, Vanessa, Ignacio Subías, José María González-Jiménez, Joaquín A. Proenza, Isabel Fanlo, Antoni Camprubí, William L. Griffin, Fernando Gervilla, Suzanne Y. O’Reilly, and Monica F. Escayola. "Metamorphic fingerprints of Fe-rich chromitites from the Eastern Pampean Ranges, Argentina." Boletín de la Sociedad Geológica Mexicana 72, no. 3 (November 28, 2020): A080420. http://dx.doi.org/10.18268/bsgm2020v72n3a080420.

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Abstract:

Chromitites hosted in the serpentinized harzburgite bodies from Los Congos and Los Guanacos (Eastern Pampean Ranges, north Argentina) record a complex metamorphic evolution. The hydration of chromitites during the retrograde metamorphism, their subsequent dehydration during the prograde metamorphism and the later-stage cooling, have resulted in a threefold alteration of chromite: i) Type I is characterized by homogeneous Fe3+- and Cr-rich chromite; ii) Type II chromite contains exsolved textures that consist in blebs and fine lamellae of a magnetite-rich phase hosted in a spinel-rich phase; iii) Type III chromite is formed by variable proportions of magnetite-rich and spinel-rich phases with symplectitic texture. Type I chromite shows lower Ga and higher Co, Zn and Mn than magmatic chromites from chromitites in suprasubduction zone ophiolites as a consequence of the redistribution of these elements between Fe3+-rich non-porous chromite and silicates during the prograde metamorphism. Whereas, the spinel-rich phase in Type III chromite is enriched in Co, Zn, Sc, and Ga, but depleted in Mn, Ni, V and Ti with respect to the magnetite-rich phase, due to the metamorphic cooling from high-temperature conditions. The pseudosection calculated in the fluid-saturated FCrMACaSH system, and contoured for Cr# and Mg#, allows us to constrain the temperature of formation of Fe3+-rich non-porous chromite by the diffusion of magnetite in Fe2+-rich porous chromite at <500 ºC and 20 kbar. The subsequent dehydration of Fe3+-rich non-porous chromite by reaction with antigorite and chlorite formed Type I chromite and Mg-rich olivine and pyroxene at >800 ºC and 10 kbar. The ultimate hydration of silicates in Type I chromite and the exsolution of Type II and Type III chromites would have started at ~600 ºC. These temperatures are in the range of those estimated for ocean floor serpentinization (<300 ºC and <4 kbar), the regional prograde metamorphism in the granulite facies (800 ºC and <10 kbar), and subsequent retrogression to the amphibolite facies (600 ºC and 4-6.2 kbar) in the host ultramafic rocks at Los Congos and Los Guanacos. A continuous and slow cooling from granulite to amphibolite facies produced the exsolution of spinel-rich and magnetite-rich phases, developing symplectitic textures in Type III chromite. However, the discontinuous and relatively fast cooling produced the exsolution of magnetite-rich phase blebs and lamellae within Type II chromite. The P-T conditions calculated in FCrMACaSH system and the complex textural and geochemical fingerprints showed by Type I, Type II and Type III chromites leads us to suggest that continent-continent collisional orogeny better records the fingerprints of prograde metamorphism in ophiolitic chromitites.

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