Structure of Release Wave Profiles and Sound Speed Measurements in Shock-compressed Cemented Tungsten Carbides up to 100 GPa

Cemented tungsten carbides (WCs) are metal matrix composites in which a large fraction of hard grains of tungsten carbide are embedded in a soft transition metal matrix (also referred to as the binder). The objective of the present investigation is to investigate the structure of shock and release waves in shock-compressed cemented WCs with 3.7 and 6.0 wt. percent cobalt binder. The measured elastic-plastic wave profiles are analyzed to obtain the elastic and plastic shock wave speeds, Hugoniot Elastic Limit, shock speed versus particle velocity relationship, longitudinal stress vs. specific volume, and material strength at the peak stress states in the cemented tungsten carbide samples. The results of the analysis indicate the cemented WCs to preserve substantial shear strength in the immediate post-yield deformation regime; however, both grades show a catastrophic drop in their shear stress carrying capacity when shocked to peak longitudinal stresses >70 GPa. Release properties of the shocked WC samples are determined from the arrival time of the release waves immediately following the shock plateau in front impact and overtake plate impact experiments. The release profiles are analyzed to provide critical high-pressure elasticity data on highly fragmented WC microstructures confined at pressures up to 100 GPa.