Effect of Ta Content on High Temperature Oxidation Performance of Nickel-based PM Superalloy

Abstract:

XRD, FEG-SEM and EDS were used to study the oxidation resistance of alloys with different Ta element contents at 800℃. The results show that the relationship between oxidation weight gain and oxidation time of Ta-containing alloys conforms to parabolic kinetics law, and the oxide layer is Al₂O₃+NiCr₂O₄+Ta₂O₅+(Ti/Cr)TaO₄ composite oxide structure, and with the increase of Ta content, the thickness of the oxide layer decreases, and the oxidation depth becomes thinner, and the oxide layer becomes smoother and denser. Experiments have found that there is a Ta-rich oxide (Ta₂O₅, (Ti/Cr)TaO₄) between the outer layer and the inner oxide layer, which can easily combine with Cr₂O₃ to form CrTaO₄, which reduces the volatilization loss of Cr₂O₃ oxide at high temperatures and improves the oxidation resistance of the alloy. Experiments show that Ta-rich Ta₂O₅ and (Ti/Cr)TaO₄ can hinder the out-diffusion rate of metal ions. The addition of Ta changes the ion diffusion rate of the oxide layer and improves the oxidation resistance of the alloy.