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

Fe100-xNix 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 less than or equal to 22 at.%, single face-centered cubic phase (Fcc) - at x > 28 at.% and two of these phases - at 22 less than or equal to x less than or equal to 28 at.%. Annealing results in formation of single fcc phase structure in the samples with x greater than or equal to 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-marten site transformation accompanied by the appearance of ferromagnetism. (C) 2001 Elsevier Science B.V. All rights reserved.