Influence of yttrium on microstructure and properties of Ti-23Al-25Nb alloy after heat treatment

The existence of yttrium in Ti-23Al-25Nb alloy and its influence on the microstructure after heat treatment of Ti-23Al-25Nb alloy were investigated using thermal analysis(DTA),EPMA,XRD and SEM. The heat treatment was determined based on DTA measurements. The compression tests at room temperature were performed on a Instron-569 universal tester. The results show that yttrium exists as the Y2O3 alloy. The addition of Y doesn't affect the characteristic phase transformation temperature. At lower quenching temperature,Y strengthens the XRD peaks of O phase by improving the decomposition of B2 phase. Yttrium addition enhances the compression properties with the compression strength,yield strength and compression ratio increasing. The strengthening is attributed to the second phase strengthening of Y2O3 particles and the grain refinement.