Functional stability of a ferromagnetic polycrystalline Ni₂MnGa high temperature shape memory alloy

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• 作者：M.A. Azeem^a ; ^b ; ^c ; ^{mohammed.azeem@manchester.ac.uk} ; N.G. Jones^a ; ^d ; S.L. Raghunathan^a ; ^e ; V.A. Vorontsov^a ; D. Dye^a ; ^{david.dye@imperial.ac.uk}
• 关键词：Ferromagnetic shape memory alloy ; Synchrotron radiation ; Thermal expansion ; Intermetallic compounds
• 刊名：Scripta Materialia
• 出版年：2017
• 出版时间：15 March 2017
• 年：2017
• 卷：130
• 期：Complete
• 页码：274-277
• 全文大小：740 K
• 卷排序：130

文摘

Electrocaloric Ni2MnGa is of interest for solid state refrigeration applications, as well as a high temperature thermal shape memory alloy. Here, polycrystalline Ni54Mn25Ga21 is examined using in situ synchrotron X-ray diffraction. The initial martensite (Mf) and austenite (Af) finish temperatures were found to be 232 ° C and 298 ° C respectively. Mf was observed to decline by 8 ° C/cycle and Af increased by 1 ° C/cycle. Both below and surprisingly, above the Curie temperature, the application of an e.m.f. was found to affect the lattice parameters measured. A change in the thermal expansion of the two phases was found around the Curie temperature.