Observation of Shock-Induced Failure of Diamond Particles using High-Speed Photography

Failure of shocked diamond particles has been observed using high-speed photography with an exposure time of 50 ns and an interframe time of 100 ns. The diamonds, which were each embedded in a transparent polymethylmethacrylate matrix,~were approximately discs of diameter~$\sim $5 mm and thickness 1~-~2 mm. Shock waves were induced in plate impact experiments. Three broad categories of failure were observed in the first microsecond after shock wave arrival. Diamonds containing pre-existing weaknesses and birefringence at crystal centres were prone to comminution.~These diamonds also developed large internal single fractures, which propagating at up to 14~$\pm $~1~mm~$\mu $s$^{-1}$, faster than the Rayleigh wave velocity. Smaller cracks observed near particle edges suggest that the flaws of dimensions up to at least 5~$\mu $m are present near unpolished diamond surfaces. The size distribution of fragments recovered from these experiments indicates that fractures interact with each