Stacking fault energies of fcc fe-Ni alloys by x-ray diffraction line profile analysis

Abstract

The stacking fault energies of the fee alloy series Fe-28 Ni to pure Ni were investigated using X-ray diffraction line profile analysis. A minimum stacking fault energy of about 70 mJ/m2 occurs at the approximate composition of Fe-40 pct Ni. From this point, the lower nickel alloys rapidly increase to a very high stacking fault energy, estimated to be 200 mJ/m2, while the energies of the high Ni alloys rise linearly to the Ni value of 214 mJ/m2. Anomalous reductions of the lattice parameter after cold work were found for the low nickel alloys; this was interpreted as evidence for Fe3Ni ordering and corrections to the stacking fault energy were made.