摘要
The nanoindentation pop-in behaviors of 13 grains with diverse crystallographic orientations were analysed using a coarse-grained Mg-2 wt.% Gd alloy.Within nanoscale stressed volumes within all grains,the converted shear stresses for the first pop-in,calculated using the indentation Schmid factor,ranged from 1 to 1.3 GPa,consistent with theoretical predictions for dislocation nucleation in Mg.The estimated activation volume of the first pop-in was approximately 27–40 A3(involving about ~2 atoms),aligning with reported atomistic simulations of the surface dislocation semi-loop nucleation.While indented near the -axis,grains exhibit higher first pop-in loads and successive pop-ins,implying the possibility of a cross-slip nucleation mechanism to accommodate -axis deformation.
基金
financial support of NSERC Discovery Grant (RGPIN-2019–05882) and Canada Research Chair program (CRC-2021–00512)。
