Atomistic Simulation on the Twin Boundary Migration in Mg under Shear Deformation.

Shichao Song,Yu Wang,Xi Wang,Yang Wang

doi:10.3390/ma12193129

Abstract

In this paper, the {} twinning and detwinning was studied by molecular dynamics simulation under different shear directions and strain rates. The results showed that the twin was thickened under [] shear direction and shrunken with shearing in the opposite direction. The critical resolved shear stress of {} twin boundary migration increased with the increase of the strain rate. By analyzing the atom’s displacement, it was concluded that the {} twin migration was achieved by both the shear and the atomic shuffling. Every atom would be affected by the shear, and different shear directions would cause opposite move directions, which led to twinning or detwinning. The atom shuffling was only used for adjusting the glide twin boundary and mirror-symmetric twin boundary structure evolution.

Highlights

Twin boundary (TB) is a special kind of two-dimensional planar defect in crystalline materials.It separates two crystalline regions structurally as the mirror images of each other
Stress tensors of the system were derived from atom stress, which was calculated by the compute stress/atom command [42] on LAMMPS
An Mgthe crystal with two twin boundaries under different shear directions different to the shuffling-dominated mechanism. Li et al They thought the and strain rates was studied by molecular dynamics simulation

Summary

Introduction

Twin boundary (TB) is a special kind of two-dimensional planar defect in crystalline materials. It separates two crystalline regions structurally as the mirror images of each other. The highly symmetrical discontinuity in structure can be produced by deformation or annealing. The structure and the properties of TBs deeply affect the mechanical properties of materials. Magnesium (Mg) and its alloys, due to their low density and high specific strength, have potential applications in automotive and aerospace industries [1]. Low strength and ductility induced by their hexagonal closed-pack (HCP) structure are the major obstacles preventing Mg alloys being widely used. Twinning is the other important deformation mechanism for

Methods

Results

Conclusion