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

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-degre es-C and aging at 750-degrees-C. By means of transmission electron mic roscopy (TEM) and diffraction techniques, the orientation relationship s between M2C (p) and the austenite (gamma) matrix were determined to be: (0001)p//(111)gamma, (1120BAR)p//(110BAR)gamma, (1100BAR)p//(112BA R)gamma. M2C carbide has been reported by many researchers to precipit ate from the ferrite matrix or along austenite/ferrite boundaries in a lloy steels containing Mo. However, little information concerning the formation of M2C in the austenite matrix has been provided. This inves tigation presents the first evidence for the existence of M2C carbide wholly within the austenite matrix and its relationship to the austeni te. The energy-dispersive spectrometry (EDS) analyses were performed o n M2C carbides, and the results indicate that the solubility of the M2 C carbide for foreign atoms other than Mo is very limited.