ORIENTATION RELATIONSHIPS BETWEEN M2C CARBIDE AND THE AUSTENITE MATRIX IN AN FE-MN-AL-MO-C ALLOY

Abstract

M2C carbides were observed to precipitate within the austenite matrix of an Fe-24-6Mn-6.6Al-3.1Mo-1.0C alloy after quenching from 1200-degrees-C and aging at 750-degrees-C. By means of transmission electron microscopy (TEM) and diffraction techniques, the orientation relationships between M2C (p) and the austenite (gamma) matrix were determined to be: (0001)p//(111)gamma, (1120BAR)p//(110BAR)gamma, (1100BAR)p//(112BAR)gamma. M2C carbide has been reported by many researchers to precipitate from the ferrite matrix or along austenite/ferrite boundaries in alloy steels containing Mo. However, little information concerning the formation of M2C in the austenite matrix has been provided. This investigation presents the first evidence for the existence of M2C carbide wholly within the austenite matrix and its relationship to the austenite. The energy-dispersive spectrometry (EDS) analyses were performed on M2C carbides, and the results indicate that the solubility of the M2C carbide for foreign atoms other than Mo is very limited.