Oxidation and Microstructural Behaviors of Ni-Based Alloys Strengthened by (Ta, Hf)C Carbides at 1250 °C in Air

Two alloys based on nickel and designed to be reinforced by MC carbides thanks the presence of Hf Ta were produced casting. They subjected 50 h-long isothermal exposure at 1250 °C in synthetic air with thermogravimetric monitoring oxidation progress. In as-cast state, they contain both significant quantities (Hf,Ta)C carbides. Their verified melting start temperatures, close 1300 °C, allowed performing planned test. The two demonstrated a chromia-forming behavior limited mass gain rates. However, also showed rather low resistance oxide spallation cooling, which is proportion Ta/Hf ratio. After h morphology had significantly evolved, from their initial script-like shape fragmented coalesced state. results are promising, but use these needs further improvements mechanical level.