Ultra-precision machining of Al/SiC composites remains challenging due to the pronounced mechanical contrast between the ductile Al matrix and brittle SiC reinforcements. Understanding their nanoscale deformation and removal mechanisms is essential for achieving high-quality surfaces. In this study, we employ a dual-mode nano-scratching approach that uniquely combines ex-situ (long tracks, 10–200 mN) and in-situ (short tracks, 0.5–20 mN) experiments to elucidate the load-dependent removal regimes and underlying damage mechanisms. The Al phase exhibits continuous plastic flow mediated by dislocation activity, accompanied by force fluctuations and variations in the friction coefficient (0.2–0.6). In contrast, the SiC phase accommodates deformation through dislocations, stacking faults, amorphization, and microcracking, showing stable force responses and a consistently low friction coefficient (∼0.1). A critical discovery is the identification of phase-sequence-dependent interfacial cracking that preferentially initiates during SiC-to-Al transitions. This behavior is driven by dislocation pile-ups at the interface and manifests as a characteristic “dip–rise” signature in the friction coefficient. Furthermore, subsurface microcracks in SiC are shown to originate from heterogeneous strain gradients transferred from the overlying Al rather than direct loading. With increasing loads, SiC fracture becomes dominant, producing extensive surface and subsurface damage. Under the maximum load (200 mN), the Al matrix undergoes pronounced grain refinement via the cooperative action of continuous and discontinuous dynamic recrystallization. Collectively, these findings uncover phase-specific deformation pathways and interfacial dynamics, providing a mechanistic foundation for optimizing the ultra-precision machining of heterogeneous composites.
扫码关注我们
求助内容:
应助结果提醒方式:
