Experimental study of asymmetrical tilt boundaries in WC-Co alloys

Abstract

The rotation angle distribution of grain boundaries with [2 -1 -1 0] misorientation axis in WC-Co alloys was investigated by electron backscatter diffraction for a range of cobalt contents. The effect of carbon content and sintering time was also studied. Preferred misorientations correspond to low-index boundary habit planes involving the basal or prismatic plane for at least one grain. The 26.2° [2 -1 -1 0] boundary was imaged by high resolution transmission electron microscopy. The joining of the mismatched planes at the boundary is accommodated by dislocations which are interpreted with reference to the 29.4° [2 -1 -1 0] boundary. The dislocation spacing and direction found experimentally are in agreement with calculated values obtained by the 02-lattice approach taking into account the misorientation and parametric misfit. The periodicity and characteristics of the dislocations indicate an optimization of the grain boundary structure and energy.