Analysing single twinning events in Mg-6Zn using nanoindentation

The present work addresses the challenge of estimating the twin thickening stresses. Single twinning events were captured in solution treated and peak-aged Mg-6Zn alloy subjected to {101¯0} nanoindentation. Markedly different responses of twinning to aging are seen compared to slip. 3D EBSD and high resolution EBSD are combined with crystal plasticity finite element modelling to fully characterize the twinning event. A model is then derived to allow us to estimate the influence of alloying with Zn and peak aging on the stresses required for twin thickening using the depth of the pop-in and the nanoindentation hardness before twinning. The stress for twin thickening increases from 6 MPa to 26 MPa and 74 MPa with an error of ± 10% due to the addition of solute Zn and the presence of particles formed during peak aging respectively.