The lattice parameters of austenite and ferrite in FeC alloys as functions of carbon concentration and temperature

Abstract

Despite its relevance for various calculations involving phase transformations in Fe-C alloys, little information is available on the lattice parameter of austenite at elevated temperatures and its dependence on the carbon concentration. Furthermore, severe scatter exists in the literature for the lattice parameter at high temperature. Most literature data were acquired using X-ray diffraction, although neutron diffraction seems to be a more suitable technique penetrate and probe a large volume of material, the advantages of neutron diffraction over X-ray diffraction are its reduced sensitivity to surface decarbonization and improved crystal statistics (both decarbonization and grain growth can occur during diffraction experiments at high temperatures requiring long exposure times). In this work in-situ neutron diffraction experiments on Fe-C alloys were performed to determine the lattice parameter of the austenitic and ferritic phases in a temperature region from just below to just above the bi-phasic austenite/ferrite region.