Oxidation resistance of TiAl alloy treated by plasma Nb–C alloying

In this paper, the duplex treatment of plasma surface niobizing and carburization (Nb–C alloyed or duplex treated) has been performed on TiAl substrates. Cyclic-oxidation tests for untreated and duplex treated TiAl were carried out in static air at 900 °C for 103 h. The mass gain due to oxidation was measured using an electrobalance. The chemical compositions of the Nb–C alloyed layer as well as its microstructure were examined by glow discharge spectrum (GDS) and the optical microscopy (OM). The electronic diffraction spectrum (EDS) and scanning electronic microscopy (SEM) were used to analyze and observe the oxide layers. The phase structures of the oxide scale were identified by X-ray diffraction (XRD). The results show that the oxidation rate of the duplex treated TiAl specimens decreased significantly, compared with the untreated TiAl. The roles of duplex treatment for improving the oxidation resistance are discussed.