Effect of titanium on the kinetics of the σ-phase formation in a coarse-grained Fe–Cr alloy

Abstract The influence of titanium on the kinetics of the σ-phase formation promoted by an isothermal annealing at T =973 K was studied in coarse-grained quasi-equiatomic Fe–Cr alloys by using the 57 Fe Mossbauer Spectroscopy. It was found that the kinetics could be well-described in terms of the Johnson–Avrami–Mehl equation. The addition of titanium (up to 3 at%) was revealed to effect the transformation kinetics in the following way: for x Ti ⩽1.5 at%, its presence accelerates the process with the highest transformation rate for x Ti =0.3 at%, for x Ti ⩾1.5 at%, titanium retards the formation of the σ-phase. Quantitatively, the effect of titanium on the kinetics was described in terms of a change of the effective activation energy.