Hot Extrusion Enhanced Homogenization of Microstructure in a Spray Deposition Aluminum Alloy

Homogeneous heat treatment serves the significant roles in eliminating the segregation and tuning the microstructure of alloy ingot. It usually cost tremendous power and time to achieve a homogeneous microstructure for aluminum alloys. In this article, the hot extrusion was directly introduced on the spray deposited aluminum alloy 7055 ingot before performing heat treatment to explore the newly feasible homogeneous routine. Equiaxed grains without dendrites or PPB were obtained in our current parameters of spray deposition, which allowed the as-deposited alloy to be deformed without being subjected to pre-homogeneous heat treatment. Significant amount of stored energy was produced during hot extrusion at 420 °C with area reduction ratio of 6.25, which effectively promoted the homogeneity of microstructure and reduced significantly the heat treatment time. A newly feasible short routine, heat treatment at 450 °C /6 h + 470 °C/1 h following the hot extrusion, proved capable of obtaining a homogeneous microstructure for the spray deposited aluminum alloy 7055.