Nanocalorimetry and Ab Initio Study of Ternary Elements in CuZr-Based Shape Memory Alloy
Nanocalorimetry and Ab Initio Study of Ternary Elements in CuZr-Based Shape Memory Alloy
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DOI：
10.1016/j.actamat.2019.10.025
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发表时间：
2020-01
期刊：
影响因子：
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通讯作者：
Y. Miao;R. Villarreal;A. Talapatra;R. Arróyave;J. Vlassak
中科院分区：
文献类型：
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作者：
Y. Miao;R. Villarreal;A. Talapatra;R. Arróyave;J. Vlassak
对CuZr基形状记忆合金的三元合金化效应进行了计算-实验研究。采用纳米量热法研究了Cu-Zr-X（X = Ni，Co，Hf）薄膜的晶化、马氏体-奥氏体相变温度和相变滞后等相变行为。我们使用从头算模拟，以确定B2-Cm转换途径，评估的晶格参数，相对相稳定性，和孪晶界面能作为一个功能的组成。实验结果表明，Ni或Co合金化使马氏体相变滞后减小，而Hf合金化使马氏体相变滞后增大，这与马氏体相变矩阵的中间特征值的变化趋势相一致。从模拟获得的纯相之间的能量差表明，钴和镍稳定马氏体对奥氏体。然而，实验表明Co降低了相变温度，而Ni提高了相变温度，我们将这一观察结果归因于含Co合金中较大的孪晶晶界能和应变能。我们的研究结果表明，从头算模拟是一个有用的工具，在新的形状记忆合金的发展，提供与马氏体的精细孪晶结构的能量项被考虑在内。
We present a computational-experimental study on the ternary alloying effect of CuZr-based shape memory alloy. The transformation behavior, including crystallization, martensite-austenite transformation temperature and hysteresis of Cu-Zr-X (X = Ni, Co, Hf) thin-film samples were investigated by nanocalorimetry. We usedab initiosimulations to determine the B2-Cm transformation pathway, evaluate the lattice parameters, the relative phase stability, and the twin boundary energy as a function of composition. Experimental results show that alloying with Ni or Co reduces the hysteresis of the martensitic transformation, while Hf increases it. These observations are in agreement with the trend of the middle eigenvalue of the martensitic transformation matrix. The energy difference between the pure phases obtained from simulations suggests that both Co and Ni stabilize martensite against austenite. However, experiments show that Co decreases transformation temperature, while Ni increases it. We attribute this observation to the larger twin boundary energy and strain energy in the Co-containing alloy. Our results indicate thatab initiosimulations are a helpful tool in the development of new shape memory alloys, provided the energy terms associated with the fine twin structure of the martensite are taken into account.