Chemistry-mediated microstructural heredity in WA-DED Mg-Gd-Y-Zn-Zr alloys: effect of feedstock wire state on hydride formation, heat treatment response and mechanical properties

The influence of feedstock wire state on the microstructural evolution and mechanical properties of wire arc directed energy deposited (WA-DED) Mg-rare earth (RE) alloys remains poorly understood. Here, two hot-drawn Mg-Gd-Y-Zn-Zr wires with similar nominal compositions but distinct initial states were deposited under identical cold metal transfer WA-DED conditions. Despite the pronounced differences between the feedstock wires, both as-deposited alloys developed comparable equiaxed grain structures and weak textures, demonstrating that the rapid solidification and thermal cycling inherent to WA-DED largely eliminate the direct inheritance of feedstock grain morphology and texture. In contrast, the phase constitution remained strongly dependent on the feedstock state, with the wire B deposit exhibiting a substantially higher volume fraction of the cubic (Gd,Y)H 2 phase. Following solution treatment and aging, the wire A deposit exhibited a stronger age-hardening response and higher tensile strength, whereas the wire B deposit retained higher ductility but showed a reduced strengthening response. These differences are attributed to feedstock-dependent phase evolution, which modifies the solute available for subsequent precipitation and thereby affects the precipitation response and mechanical behavior. The results demonstrate that the influence of feedstock state in WA-DED Mg-Gd-Y-Zn-Zr alloys is associated with phase-mediated solute redistribution rather than by direct inheritance of the initial grain structure and texture, ultimately governing the age-hardening response and strength-ductility balance.