Effect of initial microstructure on phase transformation and mechanical properties of Ti–3Al–5Mo–4Cr–2Zr–1Fe alloy

Phase transformation, microstructure evolution, and mechanical properties of Ti–3Al–5Mo–4Cr–2Zr–1Fe alloy were investigated during a continuous heating process. Three microstructures, specifically lath, duplex, and lamellar structures, were examined. The activation energies for phase transition in these structures were measured as 277, 220, and 193 kJ mol⁻¹, respectively. The phase transition follows: For the lath structure, β transforms into α_acicular (550–660°C), α_acicular converts to β (660–785°C), α_lath does to β (660–850°C); For the duplex structure, β transforms into α_acicular (545–660°C), α_acicular converts to β (660–770°C), α_lath does to β (660–850°C); For the lamellar structure, β transforms into α_secondary (560–615°C), α_secondary converts to β (615–705°C), α_lamellar dose to β (615–850°C). The lath and duplex structures exhibited favorable comprehensive properties compared to lamellar microstructure.