Influence of matrix characteristics on tensile properties of in situ synthesized TiC/TA15 composite

In the present paper, in situ synthesized 10 vol.% TiC/TA15 composite has been fabricated by induction melting and common casting utilizing the reaction between titanium and C powder. Three types of heat treatment processes were performed on the as-cast composite and, accordingly, fine fully lamellar, bi-modal and near-equiaxed microstructures were obtained. The tensile properties were tested at room temperature, 600 °C and 650 °C. The results show that heat treatment can evidently enhance UTS below 600 °C. The increased UTS is accompanied by the rapid decrease in tensile elongation at room temperature. As tensile temperature increases to 650 °C, the discrepancy in UTSs of the composite with different matrix microstructures becomes small. The composite with fine fully lamellar microstructure exhibits a good combination of relatively high UTS and high tensile elongation in comparison with that with bi-modal and near-equiaxed microstructures. Below 650 °C, the damage of the composite before and after heat treatment is mainly initiated by the fracture of TiC particles followed by the ductile failure of the matrix.

► Heat treatment can enhance UTS markedly below 600 °C.
► Increased UTS is accompanied by a rapid decrease in ductility at room temperature.
► The effect of matrix characteristic on UTS is very small at 650 °C.
► Fine lamellar microstructure shows a good combination of high UTS and elongation.
► Particle fracture dominates the failure of the composite below 650 °C.