Microstructure and beta grain growth behavior of Ti-Mo alloys solution treated

The microstructure and grain growth kinetics of Ti-Mo binary alloys in the β phase have been studied. The results show that the phase composition and grain growth kinetics of the solution-treated alloys are sensitive to Mo content. Ti-1Mo alloy mainly containes hexagonal α phase, while Ti-4Mo alloy is composed of dominated β phase and some inner acicular α′. When Mo content increases to 10 wt% or higher, the retained β phase becomes the only phase. The β grain size is not only related to temperature and solution time, but also relates to Mo content. The grain growth rate of Ti-4Mo alloy during solution treatment is much faster than that of Ti-20Mo alloy, and the time exponent 0.42 of the Ti-4Mo alloy is higher than that of Ti-20Mo alloy due to the low dislocation density. However, the grain-growth activation energy of Ti-20Mo alloy is 272.16 kJ/mol, which is much higher than that of Ti-4Mo alloy, due to the “solute drag effect” of Mo. The room-temperature strength and plasticity of Ti-Mo alloys increase with the increasing of Mo content and decreasing of grain size.