Mechanical properties and indentation-induced phase transformation in 4H–SiC implanted by hydrogen ions

Abstract

This paper aims to improve machining efficiency, suppress surface cracking, and reduce subsurface damage of silicon carbide (SiC). Hydrogen ions were implanted into SiC to study mechanical properties at nano and macro scales. Nanoindentation experiments were conducted using a Berkovich indenter. Firstly, the effect of ion implantation on the load-displacement curves at different indentation depths was investigated using molecular dynamics (MD) simulations. Elastic-plasticity at nanoscale was analyzed, and the values of material properties were obtained. Secondly, variability of surface morphology, phase transformation, and coordination number induced by nanoindentation with and without ion implantation was evaluated. Although ion implantation induced damage to the SiC model, the damage after nanoindentation was lower than that without ion implantation. Additionally, nanoindentation experiments were performed for small loads and high loads, respectively. The small load experiments were employed to derive material properties of the ion-implanted SiC. Improvement mechanisms of ion implantation on crack extension, fracture toughness, and elastic recovery rate were investigated under the high-load experiments. The results indicate that the amorphous structure induced by ion implantation can successfully prevent crack propagation and improve fracture toughness. The modification technology of SiC by ion implantation significantly improves the machining efficiency and the non-damage of its surface and subsurface.