In situ boron carbide-titanium diboride composites prepared by mechanical milling and subsequent Spark Plasma Sintering

Boron carbide - titanium diboride composites were synthesized and consolidated by Spark Plasma Sintering ( SPS) of mechanically milled elemental powder mixtures. The phase and microstructure evolution of the composites during sintering in the 1,200 - 1,700 degrees C temperature range was studied. With increasing sintering temperature, the phase formation of the samples was completed well before full density was achieved. The distribution of titanium diboride in the sintered samples was significantly improved with increasing milling time of the Ti - B - C powder mixtures. A bulk composite material of nearly full density, fine uniform microstructure, and increased fracture toughness was obtained by SPS at 1,700 degrees C. The grain size of boron carbide and titanium diboride in this material was 5 - 7 and 1 - 2 mu m, respectively.