Thermal stability of bulk nanocrystalline Ti–10V–2Fe–3Al alloy

Thermal stability of the nanocrystalline Ti–10V–2Fe–3Al alloy produced by cold-forging and corresponding hardness variations were investigated. When the annealing temperature was lower than 400 °C, the primary features were the decline of lattice defect density and the increase of lattice ordering level in the vicinity of grain boundaries, named as grain boundary relaxation. The nanocrystalline grains grew slowly. In comparison, when the annealing temperature was higher than 400 °C, the decomposition of the deformation-induced α″ martensites and the subsequent rapid grain growth were observed. Vickers hardness measurement shows an initial hardening followed by a softening with the increase of annealing temperature. The hardening peak appeared at 400 °C. The critical grain growth temperature, i.e., Tcgg, in the nanocrytalline Ti–10V–2Fe–3Al alloy, was slightly lower than those in other nanocrystalline alloys. That could be attributed to the martensitic decomposition-induced grain growth in this alloy.