Origin of the ω-Strengthening and Embrittlement in β-Titanium Alloys: Insight from First Principles
2021
The ω-phase precipitates in β-Ti alloys increase the strength but
significantly degrade the ductility of the alloys. In the present work, the
mechanism of ω-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 β and ω phases are
calculated. The strengthening and embrittlement effects of the ω phase are
discussed by comparing the slip energy barriers of slip systems in the β and ω
phases with different orientation relationships. It is found that the slip
energy barriers of slip systems in the ω phase, except for $$(\bar 2020){[0001]_\omega },$$
are much higher than those of slip systems in the β phase,
which explains the ω-strengthening and embrittlement effects. The slip energy
barrier of the most active slip system in the phase, $$(\bar 2020){[0001]_\omega },$$
increases with the depletion of Mo and increasing extent of
structure collapse, suggesting that aging treatment enhances the -strengthening
and embrittlement effects.
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