基于应力诱发马氏体相变的形状记忆合金（SMA）是呈现降温制冷弹热效应的首选材料。相比呈典型一级相变的SMA，具有弱一级马氏体相变的Fe-Pd SMA （[001]晶轴取向）呈现出宽温域（~160 K）、高能效（~98%）、温变稳定（1000次加卸载后温变衰减小于0.2 K）的特点。基于前期工作，本项目将研究：（1）Fe-Pd SMA弹热效应的热力学微观机制（本质起源），即各因素对弹热效应的定量贡献；（2）不同晶轴取向Fe-Pd单晶应力场下的微观晶体学，及弹热效应的各向异性；（3）位错与畴界对Fe-Pd单晶弹热效应的影响规律。以上研究旨在揭示具有弱一级马氏体相变Fe-Pd SMA弹热效应的机制，为新型弹热制冷材料的开发利用奠定理论基础。

Shape memory alloy (SMA) exhibiting a stress-induced martensitic transformation (MT) is the most suitable material for the elastocaloric effect which was employed in the new refrigeration system. Compared with the SMA exhibiting a typical first-order MT, the Fe-Pd SMA exhibiting a weak first-order MT shows an elastocaloric effect with wide working temperature window (~160 K), high efficiency (~98%) and stable temperature change (the temperature attenuation is less than 0.2 K after 1000 times loading/unloading processes). Based on the previous study, this research will focus on: (1) the micro thermodynamics mechanism of elastocaloric effect in Fe-Pd SMA (the origin of the elastocaloric effect), in other words, the contribution of each factors to the elastocaloric effect; (2) the micro crystallography under the stress filed in the Fe-Pd single crystals with different crystal orientations, and the anisotropy of elastocaloric effect; (3) the influence of dislocation and domain boundary on the elastocaloric effect in Fe-Pd SMA. The purpose of this project is to perfect the micro mechanism of elastocaloric effect in the Fe-Pd SMA exhibiting a weak first-order MT, and to lay the groundwork for design and application of the new elastocaloric materials.