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arXiv 1804.04546cond-mat.mtrl-sci
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Ti-Ta-X记忆合金相变温度的特殊成分依赖性

Unusual composition dependence of transformation temperatures in Ti-Ta-X shape memory alloys

Alberto Ferrari, Alexander Paulsen, Jan Frenzel, Jutta Rogal, Gunther Eggeler, Ralf Drautz

摘要:

Ti-Ta-X(X = Al,Sn,Zr)化合物是一种新型的高温记忆合金(HTSMA)。单向形状记忆效应(1 WE)的稳定性、可利用的伪弹性(PE)应变间隔以及这些合金中的相变温度强烈地依赖于组成,导致稳定的形状记忆效应和高的相变温度之间的折衷。在这项工作中,实验测量和第一性原理计算相结合,以合理化的合金化的第三个组成部分,以钛钽基HTSMA的效果。最值得注意的是,一个$\textit{increase}$的转变温度随着Al含量的增加,在实验中检测到的低Ta浓度的Ti-Ta-Al,在Ti-Ta-X中的组合物的转变温度的一般观察到的依赖性。$\textit{ab-initio}$计算证实了这种趋势反转。此外,一个简单的分析模型的基础上的$\textit{ab-initio}$数据推导。该模型不仅可以解释Ti-Ta-Al三元系相变温度与组成的关系,而且为其它三元系的定性评价提供了一个快速而简洁的工具。通过预测Ti-Ta-Sn和Ti-Ta-Zr合金的相变温度的趋势来说明这一点,与现有的实验数据产生了显着的一致性。

英文摘要:

Ti-Ta-X (X = Al, Sn, Zr) compounds are emerging candidates as high-temperature shape memory alloys (HTSMAs). The stability of the one-way shape memory effect (1WE), the exploitable pseudoelastic (PE) strain intervals as well as the transformation temperature in these alloys depend strongly on composition, resulting in a trade-off between a stable shape memory effect and a high transformation temperature. In this work, experimental measurements and first-principles calculations are combined to rationalize the effect of alloying a third component to Ti-Ta based HTSMAs. Most notably, an $\textit{increase}$ in the transformation temperature with increasing Al content is detected experimentally in Ti-Ta-Al for low Ta concentrations, in contrast to the generally observed dependence of the transformation temperature on composition in Ti-Ta-X. This inversion of trend is confirmed by the $\textit{ab-initio}$ calculations. Furthermore, a simple analytical model based on the $\textit{ab-initio}$ data is derived. The model can not only explain the unusual composition dependence of the transformation temperature in Ti-Ta-Al, but also provide a fast and elegant tool for a qualitative evaluation of other ternary systems. This is exemplified by predicting the trend of the transformation temperature of Ti-Ta-Sn and Ti-Ta-Zr alloys, yielding a remarkable agreement with available experimental data.

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