Ceramic particle-induced accelerated solution-aging behavior of spray-formed 7055 aluminum alloy TIG weld metal.

The solution-aging behavior and properties of spray-formed 7055 aluminum alloy TIG weld metal (WM) reinforced by TiC–TiB2 (BC) ceramic particles are investigated, in detail. Weld joints were subjected to solution at 475 °C for 1, 2.5, and 5 h, followed by the aging process at 120 °C for 0–24 h. The results show that ceramic particles not only restrict the grain coarsening of WM during the heat treatment but also accelerate the solution and age-precipitation behavior. The optimum solution time of ceramic particle-reinforced WM is 2.5 h, which has superior aging kinetics due to the completely dissolved eutectic phases. More importantly, during the aging process, ceramic particles decrease the width of the precipitate free zone and modify the size and distribution of precipitates. With the 475 °C/2.5 h + 120 °C/15 h treatment, the tensile strength (530 ± 15 MPa) and elongation (3.9 ± 0.29%) of BC weld joints are higher than 7055 weld joints (358 ± 20 MPa, 2.38 ± 0.42%). Grain refinement, Zener pinning strengthening, coefficients of thermal expansion mismatch strengthening, and precipitation strengthening are the dominant strengthening mechanisms of ceramic particle-reinforced WM. [ABSTRACT FROM AUTHOR]