Abstract
Cold spray is a solid-state metal powder deposition technique that has proven to be highly effective in depositing a wide range of metals, including aluminum and its alloys. However, higher strength, heat treatable Al alloys appear to exhibit variable deposition efficiencies and responses to heat treatments designed to increase ductility. This work is aimed at understanding the sources of these variabilities. In this study, 6061 (0.9% Mg, 0.6% Si, 0.3% Cu, 0.1% Cr, 0.1% Fe) alloy is compared to 7075 (6% Zn, 1.6% Cu, 2.4% Mg, 0.2% Cr, 0.3% Fe) alloy. These are common heat treatable alloys, but they exhibit quite different cold spray characteristics. Generally, 7075 is more problematic in terms of deposition efficiency and the mechanical properties after heat treatment. The alloys were processed under various cold spray conditions, including laser assisted cold spray designed to soften the 7075, and subjected to heat treatments intended to increase ductility. The microstructure and mechanical properties of the as sprayed and heat-treated coatings were characterized and compared. The results of this investigation will reveal possible mechanisms explaining the different cold spray behaviors and some suggestions will be proposed to overcome the problems associated with 7075.
