Elastocaloric cooling capacity of shape memory alloys – Role of deformation temperatures, mechanical cycling, stress hysteresis and inhomogeneity of transformation
Elastocaloric cooling capacity of shape memory alloys – Role of deformation temperatures, mechanical cycling, stress hysteresis and inhomogeneity of transformation
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DOI：
10.1016/j.actamat.2017.06.012
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发表时间：
2017-08
期刊：
影响因子：
9.4
通讯作者：
Y. Wu;E. Ertekin;H. Sehitoglu
中科院分区：
文献类型：
--
作者：
Y. Wu;E. Ertekin;H. Sehitoglu
弹热（EC）效应是指形状记忆合金（SMA）在绝热条件下从马氏体逆向转变为奥氏体过程中的快速冷却。我们通过研究几种 SMA（包括 CuZnAl、NiTi、NiTiCu、Ni2FeGa 和 NiTiHf13.3）中加载状态（拉伸和压缩）、长期循环、应变局部化和变形温度的影响，对 EC 响应进行了非常全面的研究，从而扩展了现有文献。我们发现，根据熵变（高达 60 J/kg K）、应力滞后、转变的不均匀性，CuZnAl 中的温度变化为 14.2 °C，NiTi 中为 18.2 °C，NiTiCu 中为 15.2 °C，Ni2FeGa 中为 13.5 °C，Ni2FeGa 中为 13.5 °C，NiTiHf13.3 中为 6.95 °C和数量 超弹性循环。 EC 效应在拉伸状态下逐渐恶化，而在压缩状态下 EC 效应可以持续更长时间（超过 104 个周期）。 Ni2FeGa SMA 的工作 EC 温度窗口接近 200 °C，是所选 SMA 中最宽的。本文在一项研究中报告了一百多个实验，是对各种 SMA 的 EC 功能的权威总结。
Elastocaloric (EC) effect refers to the rapid cooling in shape memory alloys (SMAs) during reverse transformation from martensite to austenite under adiabatic conditions. We present a very comprehensive study of the EC response far extending the existing literature by studying the effect of loading states (tension and compression), long-term cycling, strain localization, and deformation temperatures in several SMAs including CuZnAl, NiTi, NiTiCu, Ni2FeGa and NiTiHf13.3. We found a temperature change of 14.2 °C in CuZnAl, 18.2 °C in NiTi, 15.2 °C in NiTiCu, 13.5 °C in Ni2FeGa, and 6.95 °C in NiTiHf13.3upon reverse transformation depending on the entropy change (as high as 60 J/kg K), the stress hysteresis, the inhomogeneity of the transformation and the number of superelastic cycles. A gradual deterioration of the EC effect in tension develops, while in compression the EC effect can be sustained much longer (in excess of 104cycles). The Ni2FeGa SMAs possess an operational EC temperature window of nearly 200 °C, which is the widest among the chosen SMAs. With over one hundred experiments reported in one study, this paper represents an authoritative summary of the EC capabilities of a wide range of SMAs.