Effect of Al2O3 and AICrN coatings on 950°C cyclic oxidation behaviours of y-TiAl

Purpose: The reason for this research is to test the intermetalic alloy with coatings Al2O3 and AlCrN improved oxidation resistance in air at temperatures 950°C, typical for working conditions of highly loaded parts of gas turbine. Design/methodology/approach: The objectives were achieved using several techniques including conventional metallography, SEM, BSE, EDX and precision measurements of mass loss. The oxides scales and their effects were investigated at temperatures 950°C. Findings: This investigation confirms that the deposited AlCrN coating significantly reduces spalling processes and makes for lesser mass growth of the oxidized alloy. Heat resistance of the alloy coated with a protective film of Al2O3 is higher than in the initial state alloy. This coating adds to reducing the oxidation rate and causes the mass growth to be smaller compared to the uncoated layer. Research limitations/implications: The basic limitations concern alloys in another temperature and also, atmosphere with content of SO2 should be tested. Practical implications: One of practical outcomes is to select the coatings which guarantee the reduction of oxidation behavior. It is recommended to use alloys with Al2O3 and AlCrN coatings. Originality/value: Original value of the paper is assessing of the oxidation resistance of Ti-46Al-7Nb-0.7Cr-0.1Si-0.2Ni-based intermetallic alloy with the Al2O3 and AlCrN coatings. The novelty of this research deals with the mechanism of oxidation alloy with this coatings. This knowledge can support the design of parts made of the intermetalic alloy. The problem considered is currently important for aeroplane and automotive industry, especially for gas turbine manufacturers.