Mechanical properties and nanostructure evolution of cold sprayed AA7050 after in-situ laser heat treatment

This presentation will discuss the impact of heat treatment by in-situ laser heating on the tensile properties and nanostructure evolution of cold sprayed AA7050 material. Previous research has demonstrated that the heat treatment of cold sprayed materials improves their elongation to failure. In this research, a diode laser was applied to induce an in-situ heat treatment to cold sprayed AA7050. Heat input from the laser source was systematically controlled to improve the elongation in the deposit and limit the downgrade of the substrate by not over-aging it. The cold sprayed deposit after laser heat treatment with an optimal heat input showed an increase in ductility. The recrystallized grains in the cold sprayed deposit was coarsened by the laser heat treatment, whereas the grains size in the substrate remained the same. Precipitates evolution induced by the heat treatment in the deposits and substrates were studied by transmission electron microscopy. After in situ heat treatment, the density of eta and eta-prime precipitates significantly increased in the cold sprayed deposits. The finely distributed precipitates in the T7 tempered substrate was coarsened by the laser heating. The degree of nucleation and coarsening of precipitates is a strong function of the heat input employed during laser heating.