Direct evidence for the formation of ordered carbides in a ferrite-based low-density Fe-Mn-Al-C alloy studied by transmission electron microscopy and atom probe tomography

摘要

We study the structure and chemical composition of the κ-carbide formed as a result of isothermal transformation in an Fe-3.0Mn-5.5Al-0.3C alloy using transmission electron microscopy and atom probe tomography. Both methods reveal the evolution of κ-particle morphology as well as the partitioning of solutes. We propose that the κ-phase is formed by a eutectoid reaction associated with nucleation growth. The nucleation of κ-carbide is controlled by both the ordering of Al partitioned to austenite and the carbon diffusion at elevated temperatures.