Improving the functional stability of TiNi-based shape memory alloy by multi-principal element design
Journal
Materials Science and Engineering A
Journal Volume
872
Date Issued
2023-05-08
Author(s)
Lu, Nian Hu
Abstract
This study investigated the evolutions of the superelasticity and elastocaloric effect of a multi-principal element Ti40Zr10Ni40Co5Cu5 strain glass alloy during 3001 cyclic compressions. The results were compared with a conventional solution-treated Ti49Ni51 shape memory alloy. The Ti40Zr10Ni40Co5Cu5 strain glass alloy exhibited a higher hardness, lower residual strain, and lower dislocation density due to multi-principal element solid solution strengthening and strong lattice distortion. Furthermore, it showed stable critical stress and elastocaloric cooling temperature drop during the cyclic test, and the values were maintained at 90.9 and 83.3 % after 3001 cycles, respectively. Digital image correlation analyses showed that the Ti40Zr10Ni40Co5Cu5 strain glass alloy exhibited a more homogeneous martensitic transformation behavior instead of the localized Lüders-type one. This feature originated from the high density of atomic defects, which in turn improved the temperature uniformity of the material during elastocaloric cooling. Experimental results demonstrated that the multi-principal element design method effectively suppressed dislocation slip and thus improved the functional stability and transformation homogeneity of the shape memory alloy, so such alloys are potential candidates for solid-state refrigerants.
Subjects
Cycle | Elastocaloric effect | Multi-principal element alloy | Shape memory alloy | Strain glass | Superelasticity
SDGs
Type
journal article