Giant elastocaloric effect and exceptional mechanical properties in an all-d-metal Ni–Mn–Ti alloy: Experimental and ab-initio studies

作者：Haile Yan, Luda Wang, Haoxuan Liu, Xiaoming Huang, Nan Jia, Zongbin Li, Bo Yang, Yudong Zhang, Claude Esling, Xiang Zhao, Liang Zuo · 发表于：Materials & Design · 年份：2019 · DOI：10.1016/j.matdes.2019.108180 · 被引用次数：141 · 研究领域：Shape Memory Alloy Transformations、Magnetic and transport properties of perovskites and related materials、Rare-earth and actinide compounds

Exploring novel materials with superior elastocaloric effect (eCE) is a central issue for the development of eCE refrigeration technique. In this work, we report a giant adiabatic temperature change ΔT ad of −20.4 K in the 〈100〉-textured all-d-metal Ni 50 Mn 31.75 Ti 18.25 bulk alloy. The ΔT ad value, comparable to that of the sate-of-the-art Ni–Ti alloys, surpasses the existing conventional Ni–Mn-based alloys. Investigations show that the giant ΔT ad is attributed to the large lattice volume change during martensitic transformation and the negligible negative contribution of magnetic entropy change owing to its weak magnetism . By performing X-ray diffraction measurements and ab-initio calculations, the weak magnetism is found to be intrinsically related to the B2 ordered structure in which the magnetic moments of the antiferromagnetically coupled Mn atoms located at 4a and 4b sites are cancelled out each other. Both experimental and theoretical studies confirm that Ni–Mn–Ti alloys possess the significantly enhanced mechanical properties compared with the conventional Ni–Mn-based alloys. Electronic structure investigations reveal that this could be ascribed to the replacement of d-d interaction for the strongly covalent p-d hybridization. Outstanding elastocaloric effect of the all-d-metal alloy opens a door for searching novel promising materials used as the elastocaloric refrigerants.