Two-Tier Compatibility of Superelastic Bicrystal Micropillar at Grain Boundary

Mostafa Karami; Zeyuan Zhu; Zhuohui Zeng; Nobumichi Tamura; Yong Yang; Xian Chen

doi:10.1021/acs.nanolett.0c03486

Two-Tier Compatibility of Superelastic Bicrystal Micropillar at Grain Boundary

Nano Lett. 2020 Nov 11;20(11):8332-8338. doi: 10.1021/acs.nanolett.0c03486. Epub 2020 Oct 20.

Authors

Mostafa Karami¹, Zeyuan Zhu¹, Zhuohui Zeng¹, Nobumichi Tamura², Yong Yang³, Xian Chen¹

Affiliations

¹ Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
² Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California 94720, United States.
³ Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong.

PMID: 33078611
DOI: 10.1021/acs.nanolett.0c03486

Abstract

Both crystallographic compatibility and grain engineering are super critical to the functionality of shape memory alloys, especially at micro- and nanoscales. Here, we report a bicrystal CuAl₂₄Mn₉ micropillar engraved at a high-angle grain boundary (GB) that exhibits enhanced reversibility under very demanding driving stress (about 600 MPa) over 10 000 transformation cycles despite its lattice parameters are far from satisfying any crystallographic compatibility conditions. We propose a new compatibility criterion regarding the GB for textured shape memory alloys, which suggests that the formation of GB compatible twin laminates in neighboring textured grains activates an interlock mechanism, which prevents dislocations from slipping across GB.

Keywords: Compatibility; Grain Boundary; Micropillar compression; Nanomechanics.