Phase evolution, high-temperature strength and oxidation response of Mo–Si–Ti alloys produced by powder metallurgy route

Molybdenum-based Mo–Si–Ti alloys with a multiphase microstructure were produced via a powder metallurgy route. The effects of the varied silicide fraction Mo-(20–50 vol%Ti5Si3) and SPS temperature 1500–1700° C on the phase evolution of the Mo–Si–Ti alloys were established. The microstructure and chemical composition of individual phases were analyzed. Thermodynamic calculations were performed at the sintering temperatures, and the predicted phase compositions were compared with the experimental results. The oxidation behaviour of the obtained alloys was evaluated at 800 ◦C and 1100° C. It was shown that a Ti5Si3 fraction of more than 50 vol % is required to ensure oxidation resistance at pesting temperature of 800° C. Hardness as well as compressive
strength in the temperature range of 800–1400 ◦C were also studied. Owing to the (Mo,Si,Ti)ss matrix, the alloy starts to plastically deform at 800° C, with a yield strength of about 1200 MPa.