Morphological stability of γ/α interface formed by carburization in Fe-C-X alloys.

Effect of alloying elements on the morphological stability of austenite/ferrite interface formed by carburization of Fe- X alloys at 850 °C and 800 °C was investigated. Planar interfaces were found when the alloying elements added were from among the following: Ti, V, Nb, Ta, Cr, Mo, W, Co, and Cu. Nonplanar interfaces with Widmanstätten-like structures and/or an isolated phase were observed when the alloying elements were from the following group: P, Al, Sb, Ni, Mn, Si, and Ge. The degree of supersaturation of C in the α phase adjacent to the γ phase front was analyzed using the concept of local equilibrium. It was confirmed that there was indeed a close correlation between the morphological stability and the degree of C supersaturation, which in itself depended on whether the alloying element added was an α or γ stabilizer and how strongly it bonded with C in the ferrite phase. [ABSTRACT FROM AUTHOR]