Microstructures Evolution and Mechanical Properties of a Powder Metallurgical Titanium Alloy with Yttrium Addition

The mechanism of the formation of Y2O3 particles and its effect on mechanical properties of Ti–Fe–Mo alloy prepared by blended elemental powder metallurgy was investigated. The results show that Y-rich particles with a low content of oxygen form in the Ti–Fe–Mo–Y alloy after sintering, instead of oxides. Only after the thermomechanical treatment can Y oxides form, so the formation of Y oxides is controlled by interfacial kinetics. More oxygen in the surrounding areas around the Y-rich particles favors the formation of oxides. The mechanical properties of powder metallurgical Ti alloy can be greatly improved by the addition of yttrium, especially after the thermomechanical treatment. The reason may be scavenging of O from the matrix and the strengthening effect of Y oxides.