Microstructure design and mechanical properties of annealed TiZrAlB alloys

The microstructure evolution mechanisms and the effects of microstructure on the mechanical properties of a TiZrAlB alloy following different annealing processes were investigated. Globularization occurred, which was promoted by the annealing time (ATI) when annealed at a temperature below the alpha-transus temperature due to boundary splitting and termination migration mechanisms. Due to the diffusion behavior of the elements, the globular structure coarsened with the ATI. As the annealing temperature (ATE) increased, a duplex microstructure with grain boundaries alpha (alpha(GB)) + acicular secondary alpha phase appeared, while, when the ATE exceeded the beta-transus temperature, a basket-weave microstructure appeared. The fine duplex microstructure and the globular structure exhibited the highest strength and the best combination of strength and ductility, respectively. In addition, the globularization, nucleation, and growth mechanisms of annealed alpha-type Ti alloys were also discussed in detail. (C) 2019 Elsevier B.V. All rights reserved.