Suppression of isothermal ω phase by dislocation tangles and grain boundaries in metastable β-type titanium alloys

Aging response of metastable beta-type Ti-25Nb-2Mo-4Sn alloys with different pre-treatments was experimentally investigated. Experimental results showed that the precipitation of isothermal omega phase can be suppressed by cold rolling prior to aging. It is considered that the dislocation tangles as well as grain boundaries play a key role in hindering the movements of dislocations necessary for the transition of beta to omega. In such a case, suppressing isothermal omega and promoting fine alpha were achieved simultaneously during aging. (C) 2012 Elsevier B.V. All rights reserved.