Fracture in titanium diboride

Transmission electron microscopy is used to examine the structure of shock-loaded titanium diboride. At a shock pressure of 1.7 GPa, fracture occurs by the nucleation and splitting of b = [001] dislocation loops in the basal plane. The tensile stress of the shock pulse opens the dislocation loops into microcracks. The dislocation loops from when point defects spontaneously condense at impurities. Dislocation loops are also left by moving dislocations in a deformation band and nucleate at pressure boundaries. (author)