Experimental studies and modeling for the transition from internal to external oxidation of three-phase Nb-Si-Cr alloys

摘要

A modified oxidation model, which assumes the cylindrical-like morphology of Cr2Nb phase, has been proposed to examine the conditions to form external scale of three-phase Nb-base alloys in this paper. The oxidation behavior of three-phase Nb-base alloys was tested at 1250 ℃ for 1 h and 7 h, and the experimental results were compared with the simulated results. The results show that the external CrNbO4 scale can be achieved by lengthradius ratio and volume fraction increasing for Cr2Nb phase. The simulated results are consistent with the experimental results.