Mechanically alloyed low-nickel austenite Fe–Ni phase: evidence of single-phase paramagnetic state

Abstract Fe 100− x Ni x alloys were obtained by a mechanical alloying technique (MA) from elemental metals. The alloys consist of: single body-centered cubic phase (bcc) at nickel concentrations ⩽22 at.%, single face-centered cubic phase (fcc) – at x >28 at.% and two of these phases – at 22⩽ x ⩽28 at.%. Annealing results in formation of single fcc phase structure in the samples with x ⩾22 at.%. According to the Mossbauer spectrometry data these annealed alloys with 22–28 at.% Ni were not ferromagnetic at room temperature. Cooling austenitic samples in liquid nitrogen as well as mechanical deformation stimulated austenite–martensite transformation accompanied by the appearance of ferromagnetism.