High-Temperature Mechanical Properties of In-Situ Synthesized 7715D Titanium Matrix Composites with Different Matrix Microstructures

7715D titanium matrix composites (TMC) reinforced with TiB fibres and La2O3 particles were in-situ synthesized through heat treatment by vacuum arc melting process. Lamellar and equiaxed microstructure could be obtained after annealed in β phase and (α+β) phase, respectively. High-temperature tensile test, creep test and heat exposure test at different temperatures were carried out for the composites with different microstructures. The results show that comparing with equiaxed microstructure, the lamellar microstructure obviously improved the high-temperature tensile strength and creep property of the composites, it could retard the micro-crack propagation after the reinforcement fracture effectively. After heat exposure at 600 ℃, the composites had the worst thermal stability, which due to the precipitation of granular brittle phases in the primary α phase of equiaxed microstructure and at the grain boundaries of lamellar microstructure. It was harmful to room temperature plasticity of the composites.