Effect of yttrium and erbium on the microstructure and superplasticity of Ti–4Al–3Mo–1V alloy

The article investigates the significant effects of yttrium and erbium on the microstructure and superplastic properties of the Ti–4Al–3Mo–1V alloy, a popular (α + β)-type titanium alloy. The study reveals that adding 0.2 wt.% yttrium significantly refines the primary β-phase grains during crystallization, while erbium does not exhibit this modifying effect. The formation of dispersed oxide particles, particularly Y2O3 and Er2O3, plays a crucial role in refining the grain structure and enhancing the superplastic characteristics. These oxide particles, formed due to the low solubility of yttrium and erbium in titanium, influence the microstructure during thermomechanical processing and superplastic deformation. The article highlights the superior stability of yttrium oxide particles during high-temperature annealing and deformation, which contributes to a more globular and recrystallized microstructure. This refinement leads to reduced flow stress during superplastic deformation, especially at lower temperatures, making the alloy more suitable for applications requiring high precision and formability. The detailed analysis of microstructural changes and the behavior of oxide particles under various conditions provides valuable insights into optimizing the superplastic properties of titanium alloys.