Evaluating the effect of yttrium as a solute strengthener in magnesium using in situ neutron diffraction

In situ neutron diffraction of two binary Mg alloys, Mg–0.5 wt.% Y and Mg–2.2 wt.% Y have been carried out in compression. The experimental data has been modelled using the elastoplastic self-consistent methodology in order to determine the critical resolved shear stress for basal slip, second-order 〈c + a  〉 pyramidal slip and {101¯2} twinning. It was found that the addition of Y strengthens all three of the deformation modes examined. However, increasing the Y   concentration from 0.5% to 2.2% showed no additional hardening in the basal slip and {101¯2} twinning modes, indicating that solute strengthening of these deformation modes is already exhausted by a concentration of 0.5% Y. Second-order pyramidal slip showed additional solute hardening at the higher concentration.