Abstract
In this work, a multi-phase cellular automaton (CA) model is extended for the quantitative simulation of peritectic phase transition. First, the effects of cooling rate/supersaturation and temperature on the peritectic transformation kinetics in Fe-C alloys are investigated by utilizing the present CA model. The CA simulations show that supersaturations in the parent phases (liquid and δ-ferrite) increase the L/γ interface growth velocity remarkably, but tinily for the δ/γ interface migration velocity. There exists a transition supersaturation for isothermal transformations, at which the growth rates of the two interfaces are equal. The transition supersaturation is found to increase with decreasing temperature. Microstructural evolution at different cooling rates during peritectic transformation is simulated using the experimental conditions. At low cooling rates, the δ/γ interface propagates at a higher velocity than the L/γ interface. At high cooling rates, however, the γ-phase grows more into the L-phase with a cellular morphology. Then, the proposed CA model is applied to simulate the microstructural evolution during peritectic reaction. It is observed that the γ-phase propagates along the L/δ interface and finally encircles the δ-phase. Meanwhile, the intervenient γ-phase grows in thickness through peritectic transformation. The CA simulations are compared reasonably well with the experimental data and analytical calculations.
Highlights
Peritectic phase transition, involving the peritectic reaction (L + δ→γ, namely the γ-phase growth along the L/δ interface) and the peritectic transformation (L→γ and δ→γ, namely the γ-phase thickening into the L- and δ-phases) [1], has attracted great interest in both academic study and industrial production
Extensive experiments have been carried out to study the peritectic solidification of Fe-C alloys by utilizing the solid/liquid diffusion couple method [4,5,6] and high temperature laser scanning confocal microscopy (HTLSCM) combined with the concentric solidification technique [3,7,8,9]
We recently proposed a quantitative multi-phase cellular automaton (CA) model that can simulate the microstructural evolution during peritectic transformation [30]
Summary
Peritectic phase transition, involving the peritectic reaction (L + δ→γ, namely the γ-phase growth along the L/δ interface) and the peritectic transformation (L→γ and δ→γ, namely the γ-phase thickening into the L- and δ-phases) [1], has attracted great interest in both academic study and industrial production. The γ-phase growth kinetics significantly influences the peritectic microstructures and, thereby, the mechanical properties of the final products [2,3]. Extensive experiments have been carried out to study the peritectic solidification of Fe-C alloys by utilizing the solid/liquid diffusion couple method [4,5,6] and high temperature laser scanning confocal microscopy (HTLSCM) combined with the concentric solidification technique [3,7,8,9]. The thicknesses of the γ-phase formed during isothermal peritectic transformation under different temperatures were measured in experiments by using the solid/liquid diffusion couple method [4,5,6]. The peritectic transformation in Fe-C alloys under a continuous cooling condition has been studied experimentally.
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