Revisiting ω phase embrittlement in metastable β titanium alloys: Role of elemental partitioning

The role of elemental partitioning between beta and omega phase in embrittling an originally ductile omega containing Ti-12Mo (wt.%) model alloy was studied using transmission electron microscopy and atom probe tomography. It is revealed that the embrittlement of this alloy already occurs after aging at 400 degrees C for as short as 10 min, when the size, inter-particle spacing and volume fraction of the omega particles remain almost unchanged. The origin of the aging-induced embrittlement is attributed to the significant rejection of Mo ( > 5 at.%) from the omega particles during aging, which leads to remarkable increase in the shear modulus ( > 30 GPa) of the omega particles, promoting intense plastic flow localization and facilitating crack nucleation prior to macroscopic yielding. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

In Ti-12Mo alloy, rejection of Mo element from omega phase particles leads to intense plastic flow localization and crack nucleation, causing embrittlement, which occurs as early as 10 minutes of aging at 400 degrees Celsius.