Mechanical Properties of <I>in situ</I> Synthesized Titanium Matrix Composites at Elevated Temperature

Abstract

TiB and TiC reinforced titanium matrix composites were produced by common casting technique utilizing the self-propagation hightemperature synthesis between titanium and B4C. The mechanical properties and fracture mechanism of in situ synthesized titanium matrix composites have been investigated by means of uniaxial tension at elevated temperatures. As temperature increases, the ultimate tensile strength decreases and ductility increases. Compared with the matrix alloy, ultimate tensile strength of the composite was improved obviously because the in situ synthesized reinforcements are very stable at elevated temperatures and can strengthen the matrix alloy effectively. The fracture behavior was dependent on temperature. The composites fail at low strain at room temperature due to the fracture of the reinforcements. As temperature increases, voids are likely to initiate and grow at the interface between the reinforcement and the matrix alloy, and their coalescence eventually leads to the fracture of the composites. The debonding between the reinforcements and the matrix alloy becomes the main reason for the composites failure.