Ductile-brittle transition mechanism of SiC particle-reinforced Al-MMCs under ultrasonic assisted grinding with single grain

High volume fraction (45 %) silicon carbide particle-reinforced Al matrix composites (SiC_p/Al-MMCs) play an important role in various engineering fields due to their excellent properties, but the high hardness and brittleness of the SiC reinforcements result in poor surface integrity during conventional grinding (CG). Ultrasonic assisted grinding (UAG) is an efficient machining process to improve the quality of finished surface for hard-brittle materials. In this study, comparison tests between UAG and CG with single grain were designed and the grinding force, specific grinding energy, material removal rate, surface and subsurface morphology, and the ductile-brittle transition mechanism of SiC particle were investigated. The results showed that ultrasonic vibration can increase the critical depth of ductile-brittle transition for SiC particles, making it easier to realize the micro brittle fracture and effectively reduce the surface and subsurface damage of SiC_p/Al composites.