Abstract In this study, we produced a novel Zr50Cu25Ni7.5Co17.5 high-temperature shape memory alloy with the aim of achieving high thermal stability and a good shape memory effect. Differential scanning calorimetry and the compression cycle were utilized to determine the phase transformation temperature and shape memory effect of the alloy, and transmission electron microscopy (TEM) was employed to investigate the microstructure and clarify the corresponding deformation mechanism. We found that the Zr50Cu25Ni7.5Co17.5 alloy exhibited excellent thermal stability and achieved the best maximum recovery strain of 6.87% (8% pre-strain) observed to date, making it a promising high temperature shape memory alloy. The TEM results indicated that, during the primary stage of the compression cycle, a small number of the (001) compound twins were de-twinning and numerous contraction twins formed. As the stress increased, increasing numbers of nanoscale (021) and (111) type-I deformation twins formed, and the shift displacement of the type-B planar defect expanded from 3d ~ (001) to 8d ~ (001). Furthermore, the newly found (111) type-I deformation twin and the extension of the type-B planar defect that contributes to the large recovery strain in the Zr50Cu25Ni7.5Co17.5 alloy were observed.

中文翻译：

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Zr50Cu25Ni7.5Co17.5 具有优异热稳定性和大回复应变的高温形状记忆合金，以及相关的显微组织变形机制

摘要 在本研究中，我们制备了一种新型 Zr50Cu25Ni7.5Co17.5 高温形状记忆合金，旨在实现高热稳定性和良好的形状记忆效果。利用差示扫描量热法和压缩循环测定合金的相变温度和形状记忆效应，并利用透射电子显微镜（TEM）研究显微组织并阐明相应的变形机制。我们发现 Zr50Cu25Ni7.5Co17.5 合金表现出优异的热稳定性，并实现了迄今为止观察到的 6.87%（8% 预应变）的最佳最大恢复应变，使其成为一种很有前途的高温形状记忆合金。TEM 结果表明，在压缩循环的初级阶段，少数（001）复合双胞胎是去孪生的，并形成了许多收缩双胞胎。随着应力的增加，形成越来越多的纳米级（021）和（111）I型变形孪晶，B型平面缺陷的位移位移从3d~（001）扩大到8d~（001）。此外，观察到新发现的 (111) I 型变形孪晶和 B 型平面缺陷的延伸，这有助于 Zr50Cu25Ni7.5Co17.5 合金中的大恢复应变。