Microstructure and properties of Ti–Co–Si ternary intermetallic alloys

Ti–Co–Si ternary intermetallic alloys with Ti5Si3 as the main reinforcing phase and intermetallic TiCo as the toughening matrix were fabricated by the laser-melting deposition (LMD) process. Microstructure of the intermetallic alloys was characterized by OM, SEM, XRD and EDS. High-temperature oxidation resistance of the alloys was evaluated by isothermal oxidation at 1173 K and metallic dry-sliding wear property was evaluated at room temperature. The effect of reinforcing phase Ti5Si3 content on hardness, oxidation and wear resistance of the alloys was investigated. Results indicate that microstructure of the alloys transforms from hypoeutectic to hypereutectic, while hardness and oxidation resistance increases with the increasing Ti5Si3 content. The alloys have good oxidation resistance at 1173 K and the oxidation kinetic curves are approximately parabolic. Wear resistance of the alloys is insensitive to the microstructure and is up to 15–19 times higher than the hardened tool steel 1.0%C–1.5%Cr under dry-sliding wear test conditions. The excellent wear resistance of alloys is attributed to the effective reinforcement of Ti5Si3 and the excellent toughness of the intermetallic TiCo.