High-temperature oxidation of Ti–Al–Si alloys prepared by powder metallurgy

Abstract

The Ti–Al–Si alloys are promising materials for high-temperature use in automotive, aerospace or cosmic industry. The main advantages of these alloys are their low density (approximately 4 g/cm3), good oxidation resistance, and mechanical properties at elevated temperatures. Addition of silicon into the Ti–Al alloys improves the high-temperature behaviour and improves compactness and adhesion of the oxide layer. The resistance against oxidation can be effectively improved also by an appropriate technology of preparation. In this work, the high-temperature cyclic and isothermal oxidation resistance of the Ti–Al–Si alloys are described. The effect of powder metallurgy production route (reactive sintering, mechanical alloying, Spark Plasma Sintering) on high-temperature behaviour was compared. Cyclic and isothermal oxidation tests were carried out at 800 °C and 1000 °C, well above the air-operating limit for TiAl. It was confirmed, that the Ti–Al–Si alloys are resistant at temperature 800 °C, where only very thin oxide layer was formed. Mechanical alloying followed by Spark Plasma Sintering improved the high-temperature behaviour of these alloys, the oxide layer was even thinner.