α″ phase-assisted nucleation to obtain ultrafine α precipitates for designing high-strength near-β titanium alloys
(1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
3. School of Metallurgy and Environment, Central South University, Changsha 410083, China)
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
3. School of Metallurgy and Environment, Central South University, Changsha 410083, China)
Abstract: The diffusion-multiple method was used to determine the composition of Ti-6Al-4V-xMo-yZr alloy (0.45<x<12, 0.5<y<14, wt.%), which can obtain an ultrafine α phase. Results show that Ti-6Al-4V-5Mo-7Zr alloy can obtain an ultrafine α phase by using the α″ phase assisted nucleation. The bimodal microstructure obtained with the heat-treatment process can confer the alloy with a good balance between the strength and plasticity. The deformation mechanism is the dislocation slip and the twinning in the primary α phase. The strengthening mechanism is α/β interface strengthening. The interface of (0001)α/(110)β has a platform-step structure, whereas / interface is flat with no steps.
Key words: alloy design; high-strength titanium alloy; α″ phase; α/β interface; twin deformation