Developing high-strength and ductile Mg-Gd-Y-Zn-Zr alloy sheet via bimodal grain structure coupling with heterogeneously-distributed precipitates

ABSTRACT Achieving high strength-ductility synergy in hard-to-deform high-alloyed Mg-Gd-Y-Zn-Zr alloys by rolling remains a great challenge. In this work, a Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt.%) alloy sheet possessing a high yield strength (YS) of ∼385 MPa, ultimate tensile strength (UTS) of ∼420 MPa and elongation of ∼19% was achieved via a single-pass hard-plate rolling (HPR) process. The high YS is mainly from amounts of submicron FGs and strong interactions between densely distributed γ′ precipitates and pyramidal dislocations in CGs. The activation of multiple slip systems, HDI-hardening effect, and crack suppression effect from γ′ particles, endow the excellent ductility. GRAPHICAL ABSTRACT IMPACT STATEMENT The hard-to-deform WE94 alloy sheet exhibiting a superior strength-ductility synergy has been prepared by a single-pass HPR process. The bimodal grain structure containing substantial ultrafine grains coupling with inhomogeneously-distributed nano-scale precipitates accounts for the superior mechanical properties.