Stress and temperature dependence of the structure of the martensite and X-phase in Ni2MnGa |
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| Authors: | Takashi Fukuda Tomoyuki Terai Hiroaki Kushida Tomoyuki Kakeshita Toyotaka Osakabe Kazuhisa Kakurai |
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| Institution: | 1. Department of Materials Science and Engineering , Graduate School of Engineering, Osaka University , 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan fukuda@mat.eng.osaka-u.ac.jp;3. Department of Materials Science and Engineering , Graduate School of Engineering, Osaka University , 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan;4. Quantum Beam Science Directorate, Japan Atomic Energy Agency , Naka-gun, Ibaraki 319-1195, Japan |
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| Abstract: | Stress and temperature dependence of the structure of the X-phase in Ni2MnGa has been investigated by neutron diffraction measurements to clarify the structural relationship among the parent (P-), intermediate (I-), martensite (M-) and X-phases. The satellite position and intensity of the X-phase differ from those of the I-phase under compressive stress, but approach those of the I-phase with increasing temperature and decreasing stress. In other words, the structure changes discontinuously with I → X transformation under compressive stress, but continuously under zero stress. On the other hand, the X → P transformation is continuous, regardless of stress or temperature. These results suggest the existence of a multicritical point for successive P → X → I transformation. |
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| Keywords: | neutron diffraction crystal structure martensitic transformation shape memory alloys incommensurate structure ferromagnetic composites Ni–Mn–Ga alloy |
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