Mechanical response and microstructure evolution of SiC particle-reinforced Al-MMCs under ultrasonic loading

High volume fraction(≥45 vol%) SiC particle-reinforced Al matrix composites are difficult for forming and manufacture. A simple and efficient method is proposed in this research to realize rapid plastic deformation at room temperature. By applying ultrasonic load to the composites, 40% compressive strain is obtained within 1 s, while the stress is only 59 MPa, about 1/10 of its compressive strength. Ultrasonic loading can produce a high instantaneous strain rate (up to 10³ s⁻¹) and a high-frequency (20000 Hz) cyclic load compared with conventional loading. The stress superposition and relief effects produced by ultrasonic loading lead to the diffusion and annihilation of dislocation in the Al matrix, the dispersion, and the plastic deformation of SiC particles. The microstructure evolution reduces the accumulation of dislocation, promotes the formation of sub-grain, weakens the deformation texture, and improves the synergetic deformation of Al and SiC.