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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. Study of the Eutectoid Transformation in Nodular Cast Irons in Relation to Solidification Microsegregation ALEXANDRE FREULON, PHILIPPE DE PARSEVAL, CLAUDIE JOSSE, JACQUES BOURDIE, and JACQUES LACAZEEutectoid transformation in cast irons may proceed in the stable or the metastable systems giving ferrite and graphite for the former and pearlite for the latter. The present work demonstrates that composition profiles across ferrite/pearlite boundaries are smooth and similar to those issued from the solidification step. No trace of long-range diffusion of substitutional solutes due to austenite decomposition could be observed. In turn, this ascertains that both stable and metastable transformations proceed with the product matrix-either ferrite or pearlite-inheriting the parent austenite content in substitutional solutes. This result sustains a physical model for eutectoid transformation based on the so-called local para-equilibrium which is commonly used for describing solid-state transformation in steels.