Efficient access to ultrafine crystalline metastable- titanium alloy via dual-phase recrystallization competition

In order to reduce the deformation resistance, the rolling process of metastable beta titanium alloys is generally carried out in the beta single-phase state, which causes the problem of non -uniform grain size during the subsequent annealing process, thus affecting the alloy properties. Here we first solution-treated the as-cast Ti-15Mo-3Al2.7Nb-0.2Si alloy at 740 C to obtain alpha + beta phase, then cold rolled it with a reduction of 60 %, and finally annealed it at 710-810 C for 2-240min. Characterization of the annealed metastable beta alloy revealed that alpha phase was involved in the rolling deformation at the same time and recrystallized on the beta matrix during the subsequent annealing process, known as equiaxial dispersion, which impeded the recrystallization of the beta grains, and ultimately an ultrafine crystalline microstructure of alpha + beta phases with an average grain size of less than 2 mu m was obtained.