Phase interface effect on spall behavior of titanium alloy at extreme strain rate

Abstract

The shock-induced spall process of the single-crystal titanium alloy with HCP phase and the dual-phase titanium alloy was simulated by the molecular dynamics method. We revealed the nucleation principle of spall void based on the tensile stress evolution. We investigated the phase interface effect on the spall behavior of the titanium alloy under extreme strain rates at the nanoscale for the first time. Compared with the single-crystal titanium alloy with HCP phase, we found that the non-planar effect of shock wave propagation occurred in the dual-phase titanium alloy due to the phase interface effect. The elastic–plastic double wave phenomenon in the dual-phase titanium alloy was weakened and the spall strength decreased. The impedance mismatch between the HCP phase and the BCC phase caused the initial void in dual-phase titanium alloy nucleated preferentially inside the high-impedance HCP phase. The secondary void at the phase interface in the dual-phase titanium alloy nucleated under the tensile stress generated by the encounter between the secondary reflected wave and the reflected wave. The void nucleation sequence in the dual-phase titanium alloy indicated that the void nucleation inside the high-impedance phase caused by impedance mismatch under the phase interface effect took precedence over the void nucleation at the phase interface.