Atomic simulation study on the effect of nanotwin on the compression behavior of Mg–Y alloys

Abstract

Twining play an important role in adjusting the mechanical properties and microstructure in magnesium alloys. In this paper, molecular dynamics simulation was used to study the deformation behavior of nanotwin boundaries, simulating the compression deformation of polycrystalline Mg–Y magnesium alloys containing nanotwin boundaries and a double crystal with {10¯12} nanotwin boundary, respectively. It was found that the nanotwin boundaries can inhibit the movement and expansion of dislocations during compression deformation, and this inhibition would be enhanced with the increase of the width of nanotwin. The twinning and basal <a> slip can coordinate the deformation of magnesium alloy, and nanotwin can inhibit the activation of pyramidal <c+a> slip. The nanotwin boundaries could reduce the stress concentration and improve the local strain unevenness. The more uniform the distribution of nanotwin boundaries was, the smaller the degree of stress concentration would be. When a force was perpendicular to the nanotwin boundary, nanotwin tended to nucleate, growth and expansion, and consume a large number of dislocations, so the failure time of the sample was delayed.