Origin of the ω-Strengthening and Embrittlement in β-Titanium Alloys: Insight from First Principles

The omega-phase precipitates in beta-Ti alloys increase the strength but significantly degrade the ductility of the alloys. In the present work, the mechanism of omega-strengthening and embrittlement is investigated by using a first principles method based on density functional theory. The generalized stacking fault energies of various slip systems in both the beta and omega phases are calculated. The strengthening and embrittlement effects of the omega phase are discussed by comparing the slip energy barriers of slip systems in the beta and omega phases with different orientation relationships. It is found that the slip energy barriers of slip systems in the omega phase, except for ((2) over bar 020){[0001](omega), are much higher than those of slip systems in the beta phase, which explains the omega-strengthening and embrittlement effects. The slip energy barrier of the most active slip system in the phase, ((2) over bar 020){[0001](omega), increases with the depletion of Mo and increasing extent of structure collapse, suggesting that aging treatment enhances the -strengthening and embrittlement effects.

Automated summary

In this study, the mechanism of omega-strengthening and embrittlement in beta-Ti alloys was investigated using density functional theory. It was found that the slip energy barriers of slip systems in the omega phase are much higher than those in the beta phase, which explains the strengthening and embrittlement effects. Aging treatment enhances the omega-strengthening and embrittlement effects by increasing the slip energy barrier of the most active slip system in the omega phase.