Microstructure and Mechanical Property Enhancement of Cold Spray Additive Manufactured Al₂O₃/2024 Aluminum Matrix Composites through Thermo-Mechanical Coupling: A Case Study on Friction Stir Processing and Hot Rolling

In this study, addressing the challenge of poor mechanical properties in cold spray additive manufacturing (CSAM) deposits, typical thermal-mechanical effects (Friction stir processing-FSP and Hot rolling-HR) were introduced into the deposit. The results indicate that multiple passes of FSP can eliminate defects caused by poor flow within the deposit, resulting in an initial decrease followed by an increase in porosity. However, the bonding quality between metal and ceramic deteriorates after three passes of FSP. Post-FSP, there is an increased disparity in microstructure, with smaller grain size and lower dislocation density observed on the advancing side compared to the retreating side, while the precipitates in the stir zone approaches the solid solution state. The optimal mechanical properties of the deposit are achieved at a traverse speed of 150 mm/min and a rotational speed of 1000 rpm, with a 43% increase in tensile strength and tensile strength and elongation reaching 406 MPa and 2.7%, respectively. After HR, the tensile strength and plasticity of the deposit increased to 439 MPa and 3.93%, respectively. The fundamental reasons for the mechanical property improvement of HR and FSP are both the conversion of mechanical interlocking between particles into metallurgical bonding.