M. Yu; Y. Li; H. Guo; H. Xiong; J. Wang; F. Wang; B. Liu; B. Hu; T. Ying; H. Wang; J. LLorca
Acta Materialia 296 (2025) 121309
Easy activation of basal dislocation causes limited ductility of magnesium, which exhibits insufficient strain hardening, leading to the localization of plastic deformation, instability and crack nucleation. Here, micropillar compression tests in a magnesium-yttrium-calcium alloy found an anomalous strain hardening phenomenon induced by interactions between basal and pyramidal <c+a> dislocations. Dislocation interactions generate strong obstacles that inhibit the continuous slip of basal dislocations, preventing deformation instabilities associated with basal slip localization. Meanwhile, the strain hardening is enhanced during plastic deformation, which would otherwise be limited by the easy glide of basal dislocations. Additionally, the activation of more <c+a> dislocations contributes to improved ductility. These dislocation interactions can be tuned by activating multiple slips via reducing the critical resolved shear stress ratio between non-basal and basal slip systems. Overall, this study offers a new fundamental perspective on promoting strain hardening and overcoming strength-ductility trade-off in magnesium alloys.