Analysis of microscopic deformation mechanism of SiCp/Al composites induced by ultrasonic vibration nanoindentation

Ultrasonic vibration machining technology affords environmentally friendly dry cutting without employing a cutting fluid and has been applied to the macro-scale dry cutting precision machining of SiCp/Al composites. However, the high-frequency vibration on the atomic-scale deformation mechanism of such materials remains unclear. Hence, this paper combines the molecular dynamics simulations (MD) with ultrasonic vibration indentation tests to investigate the effect of ultrasonic vibration on the multiscale deformation of SiCp/Al composites. The results demonstrate that the vibration amplitude exceeding the lattice constant (4.05 Å) of Al induces the plastic flow of Al atoms after breaking through the interatomic force. On the one hand, the ultrasonic high-frequency vibration energy accelerates the interfacial failure and the SiC particle fragmentation and promotes the dislocation movement to form the dislocation loop. On the other hand, compared with conventional indentation, ultrasonic vibration energy reduces the FCC phase transition rate by up to 40.8% and improves the toughness of the composites. Meanwhile, the high-frequency impact energy promotes the material to produce lattice distortion and subgranular grains, where grain slippage and lamination faults occur at the grain boundaries. Besides, the maximum depth of the material impact layer is about 1.45 times that of a conventional indentation, which contributes to the material being removed efficiently. The results of this research provide potential insights into ultrasonic vibration-assisted micro and nano removal processing of SiCp/Al composites, which could help to expand the efficient and precise clean processing of this type of material.