Origin of the O phase and its effect on the mechanical properties of rolled Ti-22Al-25Nb alloy sheets

ABSTRACT

The microstructure and mechanical properties of a hot-rolled Ti-22Al-25Nb (at%) alloy sheet after aging and solution-aging treatment were studied. A typical core-shell structure formed in the as-received specimens upon aging at 650 °C to 950 °C for 6 h. O phases precipitated around the grain boundaries or in the B2 matrix for the solution-treated specimens upon aging at 650 °C to 950 °C. The combined effect of the precipitation and solution strengthening led to a decrease in microhardness while aging from 650 °C to 900 °C and an increase in microhardness while aging from 900 °C to 1000 °C for both the as-received and solution-treated specimens after the aging treatment. Finer O phases contributed to the increase in yield strength and elongation and were more beneficial to the improvement of high temperature strength than of room temperature strength.

KEYWORDS:

• Ti₂AlNb
• O phase
• mechanical properties
• phase transformation

Acknowledgments

This work was supported by the National Natural Science Foundation of China (No. 51505323). The authors wish to express their gratitude for this funding.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51505323].