Effects of solution-aging treatment on microstructure and mechanical properties of a high-strength and high-toughness titanium alloy

Solution-aging treatment was performed to a high-strength and high-toughness titanium alloy. Several microstructural feature including volume fraction of primary α phase, size factor of primary α phase, volume fraction of secondary α phase, α_s/β interface density, were quantitatively characterized. By making a statistical analysis of the microstructure characteristics, the relationship between microstructure features and mechanical properties of the high-strength and high-toughness titanium alloy was investigated as solution temperature changed. The results show that with the increase of solution temperature in α+β phase, the volume fraction of primary α phase decreases, the size factor of primary α phase firstly decreases and then increases, volume fraction of secondary α phase increases, and the α_s/β interface density increases and then decreases. The elongation, static toughness and crack initiation energy increase with the growth of the volume fraction of primary α phase. And yield strength is positively correlated with the α_s/β interface density.