Microstructure of Y micro-alloying TiAl based alloy with high Nb content

The nominal composition of Ti-45Al-8Nb-xY (x=0, 0.1, 0.3, atom fraction/%) alloys was prepared by the non-pole-consuming vacuum arc furnace. The effect of Y addition and different homogenization treatments on the microstructure of the TiAl-based alloys with high Nb content was investigated by using the optical microscope (OM), scanning electronic microscope (SEM), X-ray diffraction (XRD), energy dispersive spectroscope (EDS). The results show that (α2+γ) lamellar colonies are refined by the element Y and the refining effect is improved with the increase of Y addition. The Y distributes along the grain boundaries and internal of lamellar colonies in the form of Y2O3 and YAl2 particles. The increase of phase transformation temperature Tα caused by the Y addition results in different microstructures formed in the TiAl-based alloys with high Nb content on the same homogenization process. ©, 2014, Cailiao Gongcheng/Journal of Materials Engineering. All right reserved.