An atom probe study of cementite precipitation in autotempered martensite in an FeMnC alloy

Atom probe field ion microscopy has been used to determine the concentration profile of the substitutional solute element manganese through cementite particles in martensite in a ternary Fe3Mn0.1C (wt%) alloy. The start temperature of the martensite reaction (Ms) in this alloy has been determined to be 380°C, which is relatively high. This means that as the specimen is quenched using helium gas, after austenitising, cementite particles are able to precipitate within the martensite plates which form at or near the Ms temperature. The atom probe results revealed that, in the case of autotempered martensite, there is no significant partitioning of the manganese between the cementite and the supersaturated ferrite matrix.