Spallation of polycrystalline tungsten using laser-induced shock at ultrahigh strain rates

Laser-induced shock technology was used to achieve the shock loading of polycrystalline tungsten (W) at an ultrahigh strain rate. The shock response and fracture behavior of W were investigated at different tensile strain rates. Unlike the intergranular fracture mode under quasistatic conditions, the transgranular-intergranularmixed fracture mode of W was detected at high strain rates and the proportion of transgranular cleavage mode increased. The spall strength of W was positively correlated to the strain rate, reaching 5.86 GPa when the tensile strain rate reached 106 s-1 in the spall plane. The mobility of screw dislocations increased at high strain rates, and the simultaneous emission of screw dislocations improved the spall strength while accelerating the expansion of crack nucleation positions, inducing numerous transgranular fractures.

Automated summary

In this study, laser-induced shock technology was used to investigate the shock loading behavior of polycrystalline tungsten at an ultrahigh strain rate. It was found that the fracture behavior of tungsten changed from an intergranular mode under quasistatic conditions to a transgranular-intergranular mixed mode at high strain rates, with an increased proportion of transgranular cleavage. The spall strength of tungsten was positively correlated with the strain rate, reaching 5.86 GPa at a tensile strain rate of 106 s-1. The increased mobility of screw dislocations at high strain rates improved the spall strength and accelerated the expansion of crack nucleation positions, resulting in numerous transgranular fractures.