High-temperature oxidation behavior of TaTiCr, Ta4Ti3Cr, Ta2TiCr, and Ta4TiCr3 concentrated refractory alloys

This study reports the unique microstructures and high-temperature oxidation behavior of TaTiCr, Ta4Ti3Cr, Ta2TiCr, and Ta4TiCr3 concentrated refractory alloys and elucidates the effect of moderate composition changes on oxidation performance. All alloys investigated in this study formed bcc solid solution matrices with second phase Laves precipitates (except for Ta4Ti3Cr, being single-phase bcc).The alloys were tested for 24 h at 1200 °C, of which: TaTiCr exhibited superior oxidation performance for the duration of the test; Ta4TiCr3 showed moderate oxidation resistance, with both parabolic and linear kinetic regimes; and Ta4Ti3Cr and Ta2TiCr both exhibited poor oxidation performance, with Ta2TiCr being completely oxidized after testing. All alloys formed complex oxides; however, the excellent performance of the TaTiCr alloy can be attributed to the compact, continuous nature of the oxide scale, the combination of complex oxides and protective Cr2O3 formation, and the complex internal nitride morphology, slowing oxygen ingress and reducing the depth of internal oxidation.