COMBUSTION SYNTHESIS DYNAMIC DENSIFICATION OF A TIB2-SIC COMPOSITE

The Ti + 2B exothermic chemical reaction was used in combination with a high-velocity forging step to produce dense TiB2-(20 vol%)SiC compos ites. Densities in excess of 96% of the theoretical were achieved for both SiC particulate and fiber additions, X-ray diffractometry reveale d the products of the reaction to be TiB2 and SIC. The microstructures are composed of spheroidal TiB, phase, a highly contiguous SIC binder phase, and an apparent eutectic between TIB2 and SIC located at regio ns of preexisting SiC additions, These microstructural features sugges t that SiC underwent a peritectic phase transformation, Thermodynamic analysis predicts that at least 41 vol% SiC addition is needed to prev ent the loss of the starting morphologies by the peritectic reaction.