Abstract Thermoelastic martensitic transformation of Ti29.7Ni50.3Hf20 alloy was studied by high-resolution and in situ real-time neutron diffraction in the temperature range from 25 °C to 250 °C upon heating and cooling. It was shown that B19′ martensite phase is characterized by strong anisotropy of thermal expansion, lattice parameters of aB19′ and bB19′ increase while cB19′ and β angle decrease with increasing of temperature. Coefficients of thermal expansion for martensite and austenite were determined. The volume effect of transformation in Ti29.7Ni50.3Hf20 alloy is 0.75% which is six times larger than that of binary TiNi alloy.

中文翻译：

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体积对 Ti29.7Ni50.3Hf20 高温形状记忆合金马氏体相变的影响

摘要 采用高分辨率原位实时中子衍射技术研究了Ti29.7Ni50.3Hf20合金在25～250℃加热和冷却过程中的热弹性马氏体转变。结果表明，B19'马氏体相具有强烈的热膨胀各向异性，aB19'和bB19'的晶格参数随着温度的升高而增大，而cB19'和β角减小。确定了马氏体和奥氏体的热膨胀系数。Ti29.7Ni50.3Hf20合金的相变体积效应为0.75%，是二元TiNi合金的6倍。