| Abstract Scope |
This presentation explores the changes in powder feedstock microstructure and cold spray characteristics over the Al-Zn-Mg-Cu system, alloys which are used in a variety of aerospace applications. Seven custom alloy powders were gas atomized, spanning the compositional space: 3-6.5 wt% Zn, 1.8-2.8 wt% Mg, and 0-2.6 wt% Cu. We also atomized AA7020, AA7075, and AA7050 feedstock for comparison. High pressure cold spray using helium gas was then employed to produce deposits under identical conditions. The deposition efficiency was stable (50-65%) across these alloys. Copper additions had the largest effect on mechanical properties and increased the yield/tensile strength, but also lowered the ductility. Surprisingly, the removal of minor alloying elements, such as Fe, Cr, and Mn, produced significant increases in ductility. The Al-5wt%Zn-2.8wt%Mg-0.2wt%Cu exhibited 17% elongation-to-failure in the as-sprayed condition; while material made from AA7020 powder, with the same Zn, Mg, and Cu levels, only reached an elongation-to-failure of 2%. |