Tuning the microstructure and mechanical properties of additive manufactured aluminum matrix composites by cold spray

Abstract

Cold spray (CS) has significant technical advantages in additive manufacturing of aluminum matrix composites. In this study, Al with different content of Al2O3 composite deposits was successfully produced by CS. The effect of Al2O3 content and heat treatment temperature on the microstructure and mechanical properties of the deposits was comprehensively studied. The results show that as the content of Al2O3 increases, the hardness, Ultimate Tensile Strength (UTS), and elongation of the deposits gradually improve in the as-sprayed state. Due to the significant hammering effect of Al2O3 particles on Al particles, there is a local metallurgical bond between adjacent Al particles in Al-50 and Al-75 deposits, and dimples appear in the fracture morphology of the deposit. With the increase of the heat treatment temperature, the diffusion of atoms at the particle-particle interface transforms the bonding between Al particles from mechanical interlocking to metallurgical bonding, so that the deposit exhibits improved ductility. However, heat treatment also eliminates the residual compressive stress and introduces grain growth through recovery and recrystallization processes, resulting in the decrease of hardness and UTS of the deposits.