Effects of Yttrium on Mechanical Properties and Microstructures of Ti-Si Eutectic Alloy

The effects of rare earth (Y) on Ti-Ti5Si3 eutectic alloy are studied. The results of microstructure analysis show that the colonies and microstructures of the raw alloy are transformed evidently with the addition of Y. With proper addition of yttrium (0.025 at %), the shape and size of the coarse Ti5Si3 phases of the colonies change to be fine and round meanwhile the microstructure of the alloy goes into uniformity. The compressive ductility and strength at room temperature are also improved. The effects of yttrium on the alloy are likely due to that Si atoms in Ti5Si3 phase are partially substituted for yttrium atoms which results in silicide Ti5(Si, Y)3 phases.