Effects of Spray Conditions and Heat Treatments on the Physical and Mechanical Properties of Al6061 Deposits Cold-Sprayed Using N2 Gas

Understanding the influence of spray conditions and post-spray heat treatments on the performance of cold-sprayed materials using N2 as the carrier gas is essential. This study examines the impact of various spray conditions and heat treatments on the physical and mechanical properties of cold-sprayed Al6061. Specimens prepared under two different spray conditions, varying the carrier gas temperature, were tested in both their as-sprayed and heat-treated states. Heat treatments, including standard and elevated temperature processes, were applied to enhance mechanical properties. Microstructural characterization was performed by assessing particle bonding quality, deformation behavior, and porosity fraction. Mechanical properties, including the yield and compression strengths, were assessed under both quasi-static compression and high-strain-rate testing at various strain rates. The physical properties, including thermal conductivity (TC), electrical conductivity (EC), and coefficient of thermal expansion (CTE), of specimens prepared under different conditions were evaluated and correlated with their mechanical properties. The results showed that the as-sprayed deposits exhibited inferior mechanical and physical properties compared to wrought Al6061. However, heat treatments improved interparticle bonding and significantly enhanced both the mechanical and physical properties, with values approaching those of wrought Al6061. Specifically, the high-temperature heat treatment performed near the solidus temperature of Al6061 resulted in properties that are closest to those of the wrought material. Statistical analysis of the results indicated strong correlations between the physical properties (TC, EC, CTE) and the compression strength, as well as among these physical properties themselves.