Investigation on the High-Temperature Oxidation Resistance of Ni-(3∼10) Ta and Ni-(3∼10) Y Alloys

Ni-(3 similar to 10) Ta and Ni-(3 similar to 10) Y alloys were fabricated by vacuum arc melting. The oxidation resistance of the alloys was studied by cyclic and isothermal oxidation tests at 800 degrees C in static air. The present work focused on the investigation of the effects of the alloying elements (Ta and Y) on the oxidation behavior of Ni-based alloys. The oxidation behavior of alloys was evaluated by mass gain, composition, as well as the microstructure of oxidized products. The experimental results indicated that Ta at a low content (3 wt %) had a positive role in enhancing oxidation resistance by decreasing the oxygen vacancy concentration of the oxide layer to prevent the inward diffusion of oxygen during oxidation, and the mass gain decreased from 2.9 mg.cm(-2) to 1.7 mg.cm(-2) (800 degrees C/200 h), while Y (3 similar to 10 wt %) degraded the oxidation resistance. However, it is worth mentioning that the pinning effect of Y2O3 increased the adhesion between the substrate and oxide layer by changing the growing patterns of the oxide layer from a plane growth to fibrous growth. Among the results, the bonding of the substrate and oxide layer was best in the Ni-3Y alloys.