2021 Volume 62 Issue 2 Pages 155-160
The kinetics of phase transformation in the Fe–C system during cooling are of great importance for controlling its microstructure and mechanical properties. However, real-time observation of the phase transformation has been a challenging task because of experimental difficulties. Here, we developed an analytical technique for time-resolved observation of the phase transformation of an Fe–C system during cooling via X-ray absorption spectroscopy with a time resolution of 200 µs. The technique was applied to model specimens: Fe, Fe–0.044C, and Fe–1.24C. The incubation time before phase transformation and the multiple steps of phase transformation from γ-Fe to α-Fe (+ Fe3C) could be clearly observed by the proposed technique, and the behaviors were significantly different among the specimens. Through the developed technique, change in atomic structures at a short-range scale was detected, which is complementary to X-ray diffraction that detects atomic structures only in long-range order. The developed technique can detect structure changes at early stage of phase transformations, where structures changes often begin at a short-range scale, and provide inevitable information on the kinetics.
