{10–12} extension twin variant selection under a high train rate in AZ31 magnesium alloy during the plane strain compression

Abstract

Twin variant selection significantly dictates the local deformation and stress field, strongly influencing the texture evolution and determining the mechanical performances of Mg alloys. In the current study, samples of magnesium alloy AZ31 were compressed in plane strain compression (PSC) at 400 °C with a strain rate of 10s−1. At a high strain rate, substantial twins were detected near the crack boundary. The orientations of selected twins and their host matrix grains were determined by electron backscattered diffraction (EBSD) techniques, and the corresponding Schmid factors (SFs) were calculated. The SF results indicate that some of the selected twins possess pretty low SFs, even negative SFs, which disobeys the SF criterion. The geometrical compatibility factors (m’) were applied to study the connected twins, and the accommodation strains were used to study the isolated twins. The connected twins are related to high m’. The selected isolated twins required the onset of ‘easy’ deformation mode (i.e. basal glide). Finally, the influence of twin variant selection on microstructural and texture evolution is discussed.