Microstructure of Al–Mg-Sc-Zr alloy cold spray deposits after heat treatment and hot isostatic pressing

Cold spraying is a coating deposition and additive manufacturing method capable of producing aluminum alloy parts at a high production rate under ambient conditions. In this work, the cold spray was applied for the deposition of AlMgScZr alloy initially developed for laser bed powder fusion additive manufacturing. The low-porosity deposits were successfully produced. Different heat-treatments as well as capsule-free hot isostatic pressing (HIP) were performed to homogenize the structure. TEM analysis of the deposits showed that heat-treatment at 300°С (3 h) + 360°С (4 h) allowed to release the Al3(Scx,Zr1-x) hardening phase with mean grain size 7.6 nm. At the same time, the heat treatment had a limited influence on the material diffusion between the splats. Hot isostatic pressing conducted at 160 MPa and 300°С (3 h) + 360°С (4 h) was more efficient for enhancing of material diffusion between splats and also allowed to the material hardening by the release of Al3(Scx,Zr1-x) hardening phase with the mean grain size 3.1 nm. The compressive strength tests revealed significant improvement of ultimate compressive strength and the strain at failure of the deposits after heat treatment and HIP.