A Combinatorial Study for Interdiffusion, Crystallography and Mechanical Behavior of Ni-Mn-Ga Alloys


Article Preview

The ferromagnetic shape memory and magnetocaloric properties of NiMnGa alloys are closely related to the martensitic transformation from high temperature austenitic phase to low temperature martensitic phase. The transformation temperature and the resulting microstructure and crystallography of the martensites can be very complex, but are crucial to the optimization of the material performance. A combinatorial study with a series of solid-to-solid diffusion couples and various characterization techniques, including scanning electron microscopy, focused ion beam, transmission electron microscopy, electron probe microanalysis, and nanoindentation, was carried out to investigate the microstructural and crystallographic development, and mechanical properties in NiMnGa alloys. Both austenitic and martensitic phases were found at room temperature in each diffusion couple with a clear interphase boundary. Crystallographic variations in martensitic phase, including non-modulated (NM) martensite and modulated (5M or 7M) martensite, were found in the diffusion couples. All martensitic microstructure consists of variants with different orientations and the twinning relationship. A decrease of reduced elastic modulus (Er) was observed with Ni substituting for Ga in the austenitic phase. However, an opposite trend of an increase in Er was found in the martensitic phase. The softening of the elastic constants near the vicinity of martensitic transformation contributed to a sharp decrease in Er near the interphase boundary. The measured Er had a larger scatter for the martensitic phase than that for the austenitic phase.



Edited by:

Prof. Andreas Öchsner, Prof. Graeme E. Murch, Ali Shokuhfar and Prof. João M.P.Q. Delgado




L. Zhou et al., "A Combinatorial Study for Interdiffusion, Crystallography and Mechanical Behavior of Ni-Mn-Ga Alloys", Defect and Diffusion Forum, Vol. 371, pp. 153-159, 2016

Online since:

February 2017




[1] K. Ullakko, J. Huang, C. Kantner, R. O'handley, V. Kokorin. Large magnetic‐field‐induced strains in Ni2MnGa single crystals, Applied Physics Letters, 69 (1996) 1966-(1968).

DOI: https://doi.org/10.1063/1.117637

[2] A.K. Giri, B.A. Paterson, M.V. McLeod, C.L. Dennis, B.S. Majumdar, K.C. Cho, R.D. Shull. Effect of crystallographic alignment on the magnetocaloric effect in alloys near the Ni2MnGa stoichiometry, Journal of Applied Physics, 113 (2013) 17A907.

DOI: https://doi.org/10.1063/1.4793608

[3] M. McLeod, A. Giri, B. Paterson, C. Dennis, L. Zhou, S. Vogel, O. Gourdon, H. Reiche, K. Cho, Y. Sohn. Magnetocaloric response of non-stoichiometric Ni2MnGa alloys and the influence of crystallographic texture, Acta Materialia, 97 (2015) 245-256.

DOI: https://doi.org/10.1016/j.actamat.2015.06.059

[4] S. Fabbrici, J. Kamarad, Z. Arnold, F. Casoli, A. Paoluzi, F. Bolzoni, R. Cabassi, M. Solzi, G. Porcari, C. Pernechele. From direct to inverse giant magnetocaloric effect in Co-doped NiMnGa multifunctional alloys, Acta Materialia, 59 (2011).

DOI: https://doi.org/10.1016/j.actamat.2010.09.059

[5] J. Pons, V. Chernenko, R. Santamarta, E. Cesari. Crystal structure of martensitic phases in Ni–Mn–Ga shape memory alloys, Acta Materialia, 48 (2000) 3027-3038.

DOI: https://doi.org/10.1016/s1359-6454(00)00130-0

[6] N. Lanska, O. Soderberg, A. Sozinov, Y. Ge, K. Ullakko, V. Lindroos. Composition and temperature dependence of the crystal structure of Ni-Mn-Ga alloys, Journal of Applied Physics, 95 (2004) 8074-8078.

DOI: https://doi.org/10.1063/1.1748860

[7] L. Zhou, C. Kammerer, A. Giri, K. Cho, Y.H. Sohn. Microstructural Development and Ternary Interdiffusion in Ni-Mn-Ga Alloys, Metallurgical and Materials Transactions A, 46A (2015) 5572-5587.

DOI: https://doi.org/10.1007/s11661-015-3123-x

[8] W.C. Oliver, G.M. Pharr. An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments, Journal of materials research 7 (1992) 1564-1583.

DOI: https://doi.org/10.1557/jmr.1992.1564

[9] W.C. Oliver, G.M. Pharr. Measurement of hardness and elastic modulus by instrumented indentation: Advances in understanding and refinements to methodology, Journal of Materials Research, 19 (2004) 3-20.

DOI: https://doi.org/10.1557/jmr.2004.0002

[10] S. Yang, C. Wang, X. Liu. Phase equilibria and composition dependence of martensitic transformation in Ni–Mn–Ga ternary system, Intermetallics, 25 (2012) 101-108.

DOI: https://doi.org/10.1016/j.intermet.2011.12.009

[11] L. Zhou, A. Mehta, A. Giri, K. Cho, Y.H. Sohn. Martensitic transformation and mechanical properties of Ni49+xMn36–xIn15 (x= 0, 0. 5, 1. 0, 1. 5 and 2. 0) alloys, Materials Science and Engineering A, 646 (2015) 57-65.

DOI: https://doi.org/10.1016/j.msea.2015.08.034

[12] P. Müllner, Z. Clark, L. Kenoyer, W.B. Knowlton, G. Kostorz. Nanomechanics and magnetic structure of orthorhombic Ni–Mn–Ga martensite, Materials Science and Engineering A, 481 (2008) 66-72.

DOI: https://doi.org/10.1016/j.msea.2006.12.215

[13] L. Mañosa, A. Gonzalez-Comas, E. Obradó, A. Planes, V. Chernenko, V. Kokorin, E. Cesari. Anomalies related to the TA2-phonon-mode condensation in the Heusler Ni2MnGa alloy, Physical Review B, 55 (1997) 11068.

DOI: https://doi.org/10.1103/physrevb.55.11068

[14] T. Brill, S. Mittelbach, W. Assmus, M. Mullner, B. Luthi. Elastic properties of NiTi, Journal of Physics: Condensed Matter, 3 (1991) 9621.

DOI: https://doi.org/10.1088/0953-8984/3/48/004

[15] M. Thomasová, P. Sedlák, H. Seiner, M. Janovská, M. Kabla, D. Shilo, M. Landa. Young's moduli of sputter-deposited NiTi films determined by resonant ultrasound spectroscopy: Austenite, R-phase, and martensite, Scripta Materialia, 101 (2015).

DOI: https://doi.org/10.1016/j.scriptamat.2015.01.009

[16] L. Zhou, A. Giri, K. Cho, H. Heinrich, B.S. Majumdar, Y. Sohn. Microstructural and Crystallographic Characterization of Ni2+xMn1−xGa Alloys (x= 0. 14, 0. 16, 0. 19, 0. 22, and 0. 24) by Transmission Electron Microscopy, Metallurgical and Materials Transactions E, 1 (2014).

DOI: https://doi.org/10.1007/s40553-014-0023-8