Effect of dual aging treatments on phase transformation and microstructure in a pre-deformed Ti2AlNb-based alloy containing O + β/B2 structures.

Abstract The effect of dual aging treatment on phase morphology, composition, and microstructure evolution of a pre-deformed Ti 2 AlNb-based alloy were investigated in this study. The 1040 °C-pre-deformed alloys were dual aged at different temperature in O + β /B2 region followed by 750 °C-aged treatment. The experimental results show that coarse O lath and lamellar O + β /B2 were formed when the aging temperature is lower than 950 °C while globular O appeared when aging temperature is higher than 950 °C. The size and content of the O phase increase and decrease with the aging temperature, respectively. Widmanstätten O + β /B2 laths were obtained after secondary aging treatment at 750 °C when the first aging temperature is higher than 910 °C. Complete lamellar O + β /B2 precipitation and coarse O lath, in particular, were obtained in the 910 °C and 750 °C dual aged alloy with no Widmanstätten O + β /B2 laths appeared. The phase content is closely related to the aging temperature. When the 970 °C-aged alloy put into the secondary aging at 750 °C, coarse O laths which were fragmented or partially spheroidized and globular O during 970 °C-aged process were dissolved and the Widmanstätten O began to precipitate inside. Highlights • Effect of dual aging treatments on phase transformation and morphology of pre-deformed Ti 2 AlNb-based alloy was presented. • No Widmanstätten O + β /B2 laths appeared in the 910 °C and 750 °C dual aged alloy. • Dissolution and regeneration of O phase during aging treatment was discovered. [ABSTRACT FROM AUTHOR]