On the decrease in transformation stress in a bicrystal cu-al-mn shape-memory alloy during cyclic compressive deformation
Journal
Materials
Journal Volume
14
Journal Issue
16
Date Issued
2021
Author(s)
Abstract
The evolution of the inhomogeneous distribution of the transformation stress (σs ) and strain fields with an increasing number of cycles in two differently orientated grains is investigated for the first time using a combined technique of digital image correlation and data-driven identification. The theoretical transformation strains (εT) of these two grains with crystal orientations [5 3 26]β and [6 5 11]β along the loading direction are 10.1% and 7.1%, respectively. The grain with lower εT has a higher σs initially and a faster decrease in σs compared with the grain with higher εT . The results show that the grains with higher σs might trigger more dislocations during the martensite transformation, and thus result in greater residual strain and a larger decrease in σs during subsequent cycles. Grain boundary kinking in bicrystal induces an additional decrease in transformation stress. We conclude that a grain with crystal orientation that has high transformation strain and low transformation stress (with respect to loading direction) will exhibit stable transformation stress, and thus lead to higher functional performance in Cu-based shape memory alloys. ? 2021 by the authors.
Subjects
Data-driven identification
Digital image correlation
Full-field stress and strain measurements
Functional fatigue
Shape memory alloys
Superelasticity
Bicrystals
Copper alloys
Crystal orientation
Grain boundaries
Metadata
Strain
Stress analysis
Compressive deformations
Cu-based shape memory alloy
Digital image correlations
Functional performance
Inhomogeneous distribution
Martensite transformations
Stable transformation
Transformation stress
Shape-memory alloy
Type
journal article