Nanoscaled Martensitic Domains in Ferroelastic Systems: Strain Glass

Title:Nanoscaled Martensitic Domains in Ferroelastic Systems: Strain Glass

Volume: 12 Issue: 2

Author(s): Dong Wang, Xiaobing Ren and Yunzhi Wang

Affiliation:

Keywords: Martensitic phase transition, nanoscaled martensite, phase field, point defect, strain glass.

Abstract: Strain glass, a frozen disordered ferroelastic state characterized by randomly distributed nanoscaled, non-ergodic martensitic domains, was recently found in ferroelastic TiNi-based alloys. Point defects like anti-site defects or dopants are found essential for the formation of the strain glass, but their role has remained obscure. In this paper, phase field method is employed to simulate how point defects change a normal ferroelastic system into a strain glass and as the result to clarify the role of point defects. We found that the local symmetry-breaking caused by the anisotropic local strain field of point defects plays a central role in the formation of strain glass. Such point-defect-induced local symmetry-breaking hinders the formation of long-range strain-ordering (twinned martensite) and results in a decrease in transition temperature Tc and a reduction of ferroelastic domain size. Above a critical defect concentration, the system transforms to a frozen state of nano-sized ferroelastic domains, i.e., strain glass. In addition, our simulation shows a gradual vanishing of heat capacity peak at the transition temperature with increasing defect concentration, and it also reproduces a characteristic non-ergodic ZFC/FC behavior of the glass state, which is in good agreement with recent experimental observations. Our results also indicate that the concentration fluctuation effect of point defects cannot stabilize a strain glass to very low temperature; thus the direct interaction between the random anisotropic strain field caused by point defects and the strain order parameter of the system is crucial for the formation of strain glass.

Cite this article as:

Wang Dong, Ren Xiaobing and Wang Yunzhi, Nanoscaled Martensitic Domains in Ferroelastic Systems: Strain Glass, Current Nanoscience 2016; 12 (2) . https://dx.doi.org/10.2174/1573413711666150523001617