Phase transformations under dynamic loading

Dynamic loading of materials on the micro-scale has become of prime importance. For phase transformations in various materials that exhibit the brittle-to-ductile transition, there is an ongoing debate as to what precise mechanisms are responsible for the transition but many theories have converged over the years. Silicon nitride was shown to undergo a phase transformation from hexagonal to the cubic phase under pressure. However, no phase transformations have been observed for silicon carbide under pressures that can be achieved during contact loading. For the case of silicon, work has been done to understand the phase transformations that take place during machining using molecular dynamics simulations. For Gallium arsenide (GaAs), the pressure-induced phase transformation during ultra-precision cutting was inferred from the high values of residual strains in the finished surface, as measured by Raman microspectroscopy. However, the pressure-induced transformation in GaAs under contact loading is not likely to occur at room temperature.