Lattice instability during the martensitic transformation in the high temperature shape memory alloy Zr(Cu0.5Co0.25Ni0.25)
Lattice instability during the martensitic transformation in the high temperature shape memory alloy Zr(Cu0.5Co0.25Ni0.25)
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DOI：
10.1016/j.jallcom.2014.08.141
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发表时间：
2015-01
影响因子：
6.2
通讯作者：
M. Azeem;D. Dye
中科院分区：
文献类型：
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作者：
M. Azeem;D. Dye
用原位同步辐射X射线衍射仪研究了多晶Zr(Cu0.5Co0.25Ni0.25)高温形状记忆合金在热循环过程中的马氏体相变。观察到单步B2↔B19‘相变，其热滞为16 1℃，马氏体终温为2 94℃。在相变过程中，观察到B19’马氏体中有大的各向异性晶格收缩和膨胀，最高可达1.3%，而B2奥氏体相变过程中没有观察到相应的变化。两相的热膨胀系数都很大，B2为33×10-6°C-1，a B19‘、b B19’和c B19‘的热膨胀系数分别为39、88和29×10−6°C−1。讨论了控制相变行为的可能机制。
The martensitic transformation on thermal cycling of the polycrystalline Zr (Cu 0.5 Co 0.25 Ni 0.25) high temperature shape memory alloy was examined using in situ synchrotron X-ray diffraction. A single step B2↔ B19′ transformation was observed with a thermal hysteresis of 161° C and a martensite finish temperature of 294° C. Large anisotropic lattice constrictions and dilations, up to 1.3%, were observed during the course of transformation in the B19′ martensite, but corresponding changes in the B2 austenite were not observed. The coefficients of thermal expansion in both phases were found to be quite large, 33× 10-6° C-1 in B2 and 39, 88 and 29× 10− 6° C− 1 for a B19′, b B19′ and c B19′ respectively. Possible mechanisms governing the transformation behaviour are discussed.