Achieving strength-ductility synergy in Mg-Gd-Y-Zn-Al alloy via toughening effect of nano-sized W-Mg3RE2Zn3 phases within LPSO structures

Abstract

By implementing an LPSO pre-kinking strategy (4 passes of ECAP) prior to hot extrusion (HE) in Mg-1Gd-6.7Y-2.5Zn-1Al alloy, nano-sized W-phase (Mg₃RE₂Zn₃) precipitates were successfully obtained, not only distributed within the α-Mg grains but also embedded within the LPSO phases. The 4P+HE alloy exhibited ultra-high strength (493.9 ± 5.1 MPa) and enhanced elongation (8.9 ± 0.5 %; a 41% increase compared to the direct HE counterpart), which can be attributed to the nano-sized W-precipitates effectively suppressing cracks propagate into the α-Mg matrix and redirecting stress concentration to brittle Al₂RE particles. This work demonstrates a synergistic toughening-strengthening mechanism through LPSO/W-phase interaction and heterostructure design, offering a novel strategy for high-performance Mg alloys.