The precipitation of FCC phase from BCC matrix in an Fe–Mn–Al alloy

The Fe-23.0 wt.% Mn-7.4 wt.% Al-0.03 wt.% C alloy, after water quenching following 1 h at 1050 °C in air, has a small amount of austenite distributed discontinuously along the grain boundaries of the ferrite phase. Aging the as-quenched alloy at higher temperatures caused precipitation of the austenite phase from the ferrite matrix preferentially along grain boundaries or within the matrix. The precipitation of the austenite phase within the ferrite matrix preferred the form of Widmanstätten side-plates. Electron diffraction studies verify that the austenite phase precipitates from the ferrite matrix. A Kurdjumov–Sachs orientation relationship holds between the BCC matrix and the FCC precipitate. The proportion of the austenite phase is larger for lower temperatures aging or furnace cooling than in the as-quenched condition.