Strength-ductility synergy enabled by morphology modulation of LPSO phases in a Cast Mg-Gd-Ni alloy

By optimizing micro-alloying and heat treatment conditions, three distinct morphologies of LPSO phase are achieved in cast Mg-Gd-Ni (Zn) alloys, while maintaining comparable LPSO volume fractions, Mg matrix composition and grain size. Unexpectedly, discontinuous intergranular LPSO, accompanied by a few LPSO fine lamellae inside grains, significantly enhanced both strength and ductility, contrary to the commonly held belief that intragranular fine lamellar LPSO precipitates are more beneficial for mechanical performance. This LPSO configuration promotes non-basal slip activation and homogeneous deformation, leading to a desirable strength-ductility synergy. These findings offer new insights into the design of high-performance Mg alloys through controlled LPSO phase engineering.