Explosive shock loading of alpha-Si3N4 powder

Alpha-Si3N4 powders were explosively shock loaded at levels of 260 and 570 kbar pressure. Specimens exhibited densification without additives into the 93 to 98-percent dense range as a result of shock-induced consolidiation. X-ray line broadening investigations indicated that significant residual, internal strain levels of the order of 0.4 percent were developed in the densified material. Hardness and indentation fracture toughness values for shock-densified regions were nearly equivalent to those for ultrahigh-pressure hot-pressed Si3N4 without densification aids.