Effect of Al content upon the stacking fault energy was investigated in the austenitic Fe–25Mn–(1.16–9.77)Al–0.68Cat% alloys by X-ray diffraction line profile analysis and thermodynamic estimation, and was considered on the basis of anomaly in shear modulus caused by the antiferromagnetic transition. The experimental results showed that the stacking fault probability decreased with increasing Al content, the observed stacking fault energy increased linearly when the Al content was lower than 6.27at%, and markedly when it was more than 6.27at%. The thermodynamic estimation indicated that the non-magnetic component of stacking fault energy increased faster than the observed one with increasing Al content in the antiferromagnetic state, and both were almost equal in the paramagnetic state. The magnetic order increased stacking fault energy in the antiferromagnetic state, and the magnetic component of stacking fault energy depended upon the average magnetic moment and Néel temperature. The increases in the localized magnetic moment and the decrease in the Néel temperature were caused by the addition of Al atoms to the austenitic Fe–Mn alloys and were accompanied by the anomaly in shear modulus, which affected stacking fault energy in the antiferromagnetic state. The anomalous drop in shear modulus led to the inconsistency for the variations of the observed stacking fault energy and non-magnetic component with Al content in the antiferromagnetic state.

Effect of Al Content on Stacking Fault Energy in Austenitic Fe–Mn–Al–C Alloys. X.Tian, H.Li, Y.Zhang: Journal of Materials Science, 2008, 43[18], 6214-22