Spinodal decomposition in Fe9.0Al30.5MnxC alloys

Abstract

The microstructures of as-rapidly solidified (RS) Fe-8.8Al-31.5Mn-xC alloys have been studied chiefly by K.H. Han and W.K. Choo. Based on their studies, it is found that in the as-RS condition, the microstructure of the Fe-8.8Al-31.5Mn-xC alloy with 0.74 [<=] x [<=] 1.62 wt pct was a single austenite phase. When the carbon content was increased to 2.02 wt pct or above, fine (Fe, Mn)[sub 3]AlC[sub x] carbides having an L[prime]1[sub 2]-type structure could be formed within the austenite matrix during the rapid solidification process. This means that the carbon content may play an important role in the formation of fine (Fe, Mn)[sub 3]AlC[sub x] carbides in the as-RS Fe-Al-Mn-C alloys. In contrast to the as-RS alloys as mentioned above, the as-quenched microstructure of the Fe-Al-Mn-C alloys, prepared by conventional casting, have also been examined by many workers. In these studies, it is seen that when an alloy with a chemical composition in the range of Fe-(8-11)Al-(28-35)Mn-(0.8-1.3)C was solution heat-treated and then quenched, the microstructure was a single austenite phase. This similar to that observed by K.H. Han and W.K. Choo in the as-RS Fe-Al-Mn-C alloys with lower carbon content. However, to date, information concerning the as-quenched microstructure of the Fe-Al-Mn-Cmore » alloy with higher carbon content is very deficient. Therefore, the main purpose of this work is to study the as-quenched microstructure of the Fe-Al-Mn-C alloy with higher carbon content.« less