Theoretical aspects of spinodal decomposition in Fe-C
B.N. Kim Lee (Lancaster University, TU Delft - (OLD) MSE-3)
J. Sietsma (TU Delft - (OLD) MSE-3, TU Delft - Materials Science and Engineering)
Maria J. Santofimia (TU Delft - (OLD) MSE-3)
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Abstract
Carbon redistribution is known to occur during room temperature aging of Fe-C martensite. One of the proposed mechanisms in the literature by which carbon redistributes is spinodal decomposition, a thermodynamically driven reaction in which the alloy undergoes separation into carbon-rich and carbon-poor regions, giving rise to modulations in carbon concentration. Despite the substantial experimental evidence supporting the occurrence of spinodal decomposition in Fe-C, its theoretical formulation requires attention. In the present study, a theoretical framework based on the regular solution model is built for evaluating the thermodynamics of the Fe-C system, with particular emphasis on the interstitial nature of carbon atoms within the ferrite lattice. Assuming a defect-free lattice, the model explains a miscibility gap in the Fe-C system. The limitations of the current model are critically evaluated.
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