Effect of E21-Fe3AlC Precipitation on Mechanical Properties of γ -Austenite Stabilized by Addition of Mn and Co

Abstract

ABSTRACTEffects of Co addition on the phase relation and mechanical properties of an E21-Fe3AlC phase in the Fe-Mn-Al-C system are investigated. The relation between the γ-austenite and E21 phases is the same with Co-free alloys. Two kinds of precipitation processes of E21 phase from γ-austenite matrix are observed: a fine E21 phase precipitation and a cellular structure formation from grain boundaries. The cellular structure formation is explained in relation to the lattice mismatch evaluated by XRD.The lattice mismatch is estimated to be ∼3%, rather higher than that of γ/γ′ in Ni-based superalloys, and the volume fraction of the E21-Fe3AlC phase precipitated in the γ-austenite phase is as large as 30%. The micro-vickers hardness increases with increasing Al or C, caused by the increase in the volume fraction of the E21-Fe3AlC phase.