Effect of shock wave duration on dynamic failure of tungsten heavy alloy

It has been well established that dynamic fracture or spall is a complex process strongly influenced by both microstructure and the loading profile imparted to the specimen. Having previously considered ductile materials with damage and deformation kinetics that are volume additive and therefore relative slow, here we consider a brittle material with damage and deformation kinetics that are fast. The present study elucidates the effect of loading profile on the fundamental mechanisms of brittle fracture in brittle tungsten heavy alloy (WHA) specimens. Spall experiments are performed with two significantly distinct shock pulse durations and accompanying unloading rates. For both profiles, it is observed that the failure in WHA is by brittle trans-particle crack growth with additional energy dissipation through crack branching in the more brittle tungsten particles. We also observe that for the 15.4 GPa peak shock stress, the wave profile does not influence the spall strength significantly. This is believed to be directly linked to the relative insensitivity of WHA to time dependent processes.