Microstructure Control Using Precipitate Phases for the Development of Heat Resistant Fe3Al-based Alloys

Abstract

AbstractA thermomechanical process (TMP) was performed to create a fine grained and recovered structure with densely formed fine particles in Fe3Al-Cr-Mo-C alloys. The TMP consists of two parts; the first part is to obtain fine recrystallised grains using coarse particles and the second to produce deformed/recovered structure using fine particles. It was found that k-Fe3AlC (E21) carbide phase tends to precipitate coarsely, which is effective to refine grain size in the first process. In a special composition range, the k carbide phase is thermo- dynamically stable in the Fe3Al matrix only at higher temperatures and fine M(Mo,Cr,Fe)2C (B81) carbide phase precipitates at lower temperatures. This fine M2C particles stabilize recovered structure by inhibiting the migration of subboundaries in the second process. This result suggests that if the fine particle density remains high, recovered structure can be maintained at 700°C.