Phase field modelling of austenite formation from ultrafine ferrite–carbide aggregates in Fe–C

Abstract

Abstract In this paper, austenite formation in an Fe – C system was simulated with a phase field approach. The model deals with a detailed description of morphological changes during austenite formation from ultrafine ferrite – cementite aggregates isothermally annealed in the intercritical region to form dual phase microstructures. Long-range diffusion of carbon is explicitly considered. The model is capable of resolving carbide particle sizes of about 100 nm to simulate the morphological complexity during austenite formation. Simulations were carried out in two- and three-dimensions. It was observed that morphological aspects of austenite formation depend significantly on spacing and distribution of cementite particles that provide suitable nucleation sites for austenite. This dependency can primarily be attributed to overlapping diffusion fields and curvature effects.