Cyclic Superelasticity, Elastocaloric Effect, and Shape Memory Effect of Solution-Treated Ti50Ni41Cu7Co2 Alloy
Journal
Materials
Journal Volume
18
Journal Issue
24
Start Page
5489
ISSN
19961944
Date Issued
2025-12
Author(s)
Abstract
Highlights: What are the main findings? Superelastic cycle test transformed the stress–strain curve into quasi-linear one with homogeneous strain. SME of 6.21% recoverable strain with 0.44% irrecoverable strain was obtained at a bias stress of 300 MPa. After training, transformation strain and elastocaloric effect became stable at 1.3%, and −4.3 K. A recoverable strain of about 0.5% was still achievable from up to 443 K. What are the implications of the main findings? Solution-treated Ti50Ni41Cu7Co2 SMA exhibited stable functionalities after 100 cycles. Cyclic superelasticity test significantly stabilizes the residual martensite even up to 573 K. Further improvement of the performance can be achieved by alloy design and microstructural control. In recent years, there has been an increasing interest in studying multi-component alloys. A bulk solution-treated Ti50Ni41Cu7Co2 SMA was prepared and investigated. The functional properties, including phase transformation temperature, shape memory effect, cyclic superelasticity, and elastocaloric response, were systematically evaluated. The alloy exhibited a Ms temperature of around 250 K, which is beneficial for applications at room temperature. Shape memory effect with a maximum recoverable strain of 6.21% was obtained under a biased stress of 300 MPa. The superelasticity rapidly became stable during the cyclic test, reducing irrecoverable strain from 2.8% to 0.01% by the 10th cycle. After 250th superelastic cycles, the alloy exhibited a stable recoverable strain of 1.3%, and a lower critical stress for transformation (270 MPa, down from 405 MPa). The elastocaloric cooling effect reached −4.9 K at the 50th cycle and stabilized at −4.3 K thereafter. With an increase in operating temperature, the elastocaloric effect diminished and disappeared above 383 K, and the SMA retained a notable recoverable strain of ~0.5% up to 443 K.
Subjects
elastocaloric effect
shape memory alloy
shape memory effect
superelasticity
Publisher
Multidisciplinary Digital Publishing Institute (MDPI)
Type
journal article