Al–Mg–Zn–(Cu) Crossover Alloy for Powder Bed Fusion – Laser Beam/Metal: Processing–Microstructure–Property Relationships

Additive manufacturing expands the processing space for aluminium alloys beyond conventional routes. Emerging Al-Mg-Zn-(Cu) alloys depict a promising alternative for automotive and aviation applications. In addition to that, the exceptional irradiation stability of T‑phase precipitates makes them particularly attractive for application in space environments. In this context, AM‑enabled repair and refurbishment offer a compelling pathway to restore component performance. We evaluate PBF‑LB/M using powder from the commercial AMAG CrossAlloy® .57. The wrought alloy was inert‑gas atomized and a portion was post‑blended with 0.9 wt.% Fe. Screening 55 parameter sets defined the process window, subsequently refined to two conditions showing relative densities above 98.5%. Processing-induced Mg and Zn evaporation reduced solute content and increased the Mg/Zn ratio. Electron microscopy revealed columnar grains and coarse Mg-Zn-Al-(Cu)-rich precipitates showing morphologies not previously observed in conventionally processed crossover alloys. As‑built tensile tests showed UTS ≈ 200 MPa with <1% elongation, and age-hardening variations confirmed limited hardening, with maximum hardness ≈ 120 HBW. The mechanical behaviour is rationalized by a reduced precipitation potential, quantified via thermochemical calculations, and by the defect structure. Based on the results we propose future design strategies for AM‑tailored chemistries as a foundation toward future repair applications of crossover alloy components.