State Key Laboratory for Advanced Metals and Materials, University of Science & Technology Beijing, Beijing 100083, China

Abstract:

The influence of Y addition on cyclic oxidation behaviors of Ti45Al8Nb alloys (at%) was investigated in air at 900 oC by SEM, XRD and EDS. Results show that proper Y addition can markedly increase cyclic oxidation resistance of the alloys. The grain sizes are gradually decreased with the increasing Y content. In cyclic oxidation tests all Y added alloys except Ti45Al8Nb0.1Y show no obvious scale spallation after 1000 cycles while Y free alloy shows serious spallation even after 300 cycles. Y addition enhances the adhesion between the oxide film and the substrate. However, alloys with excessive Y suffer severe internal oxidation by providing rapid diffusion paths for O in the form of coarse Y2O3 particles at oxide grain boundary.