Microstructural refinement and mechanical properties of Y-bearing TiAl alloys

The as-cast microstructures and tensile properties of Ti–45Al–5Nb and Ti–45Al–5Nb–0.3Y alloys were studied. With the addition of Y, YAl2 phase forms mainly along the lamellar colony boundaries as rounded or elongated particles and slightly inner the colonies as the finer particles. The microstructure of Ti–45Al–5Nb–0.3Y alloy is remarkably refined, including the lamellar colony size and lamellar spacing, compared with that of Ti–45Al–5Nb alloy. The tensile strength and ductility of Ti–45Al–5Nb–0.3Y alloy at room temperature are improved. The improvement of the Y-bearing TiAl alloy is mainly the superposition of the fine colony grain size and lamellar spacing.