Multiple slip in diamond due to a nominal contact pressure of 10 GPa at 1,000 ^°C

Abstract

From studies of anisotropy in Knoop hardness¹ and transmission electron microscopy of the deformation beneath indentations², it is widely accepted that some dislocation movement is possible in diamond at room temperature. Three-point bend tests were used earlier to identify a brittle-to-ductile transition temperature of 1,500 ^°C (ref. 3), and extensive dislocation movement was considered unlikely at lower temperatures. Here we show, however, that multiple slip can occur in diamond as a result of the pressure transmitted by the point-loading of a softer material, namely a cubic boron nitride cone at 1,000 ^°C. The method enables specimens to be prepared for electron microscopy and X-ray topography that have a controlled density of dislocations introduced at homologous temperatures below 0.3 T_m, where T_m is the melting point. Furthermore, it underlines the importance of microplasticity in the application and performance of crystalline engineering ceramics.