Effects of annealing and pulsed current treatment on the microstructure and mechanical properties of Cu/Al2O3 deposits prepared by cold spray

Cold spray additive manufacturing (CSAM) technology offers a viable way for the preparation of copper matrix composites. However, weak inter-particle bonding constrains mechanical properties of CSAMed deposits. In this work, the effects of conventional annealing and pulsed current on the microstructure and mechanical properties of CSAMed Cu/Al2O3 deposits were investigated. The results reveal that both annealing treatment and pulsed current treatment could effectively improve the microstructure and mechanical properties of the materials. Following annealing at 500 °C/2 h, the ultimate tensile strength and elongation at break of the materials increased to 145.66 MPa and 2.95%, respectively. While, when the root mean square current densities was 123.2 A/mm2, the ultimate tensile strength and elongation at break enhanced to 142.65 MPa and 5.94%, respectively, after 90 s of treatment. The microstructure evolution and fracture surface analysis demonstrated that the interface between Cu particles was effectively healed following treatment, and the fracture mechanism of the materials was transitioned from brittle to ductile mode. Nevertheless, the interface between Cu and Al2O3 particles were not substantially improved, posing a limitation to further enhancement in mechanical properties of CSAMed Cu/Al2O3 deposits.