Mechanistic insights into the link between milling-induced surface layer particle damage and mechanical property evolution of SiCp/2009Al composite thin-walled parts

SiC particles are crucial for enhancing the stiffness and strength of SiCp/Al composites and their thin-walled parts. However, the milling process inevitably induces surface layer particle damage, potentially impacting the performance of SiCp/Al thin-walled parts. Moreover, establishing a theoretical link between milling-induced particle damage and the evolution of mechanical properties remains an open problem. To address these challenges, this paper investigates the effects of different milling parameters on the surface layer particle damage and mechanical properties of SiCp/Al thin-walled parts with varying particle content and wall thickness. The results showed that milling led to surface layer particle fracture, debonding, and matrix cracking, which weakened the mechanical properties of SiCp/Al thin-walled parts. The failure process followed a synergistic load-bearing mechanism involving brittle fracture of particles and ductile fracture of the matrix. Furthermore, based on micromechanical theory, this study developed predictive models for the effective modulus and yield strength of SiCp/Al thin-walled parts, considering milling-induced particle damage. The model accuracy was verified through a series of mechanical property tests. Additionally, the stress and damage probability of particles and the contributions of different strengthening mechanisms were studied. The intrinsic link between "process parameters – surface layer particle damage – mechanical property evolution" was elucidated through experimental verification and theoretical analysis. This work provides new perspectives and guidance for the reliability engineering applications of SiCp/Al thin-walled parts and other particle-reinforced composites.