Effect of cooling rate on mechanism of β → α phase transformation on continuous cooling in Ti-5Ta-1.8Nb alloy

► β phase undergoes primarily a diffusional transformation at all cooling rates (1-99 K/min). ► With increase in cooling rate, microstructural parameters vary systematically. ► Composition of retained β phase increases with cooling rate. ► Solute enrichment during cooling induces secondary phase transformations of β phase. ► Diffusionless α″/ω and diffusional α form at high and low cooling rates respectively.