Study of alloying mechanisms of ball milled Fe-Cr and Fe-Cr-Co powders

Mechanical alloyed Fe-31Cr and Fe-31Cr-12Co powder mixtures have been investigated using 57Fe Mössbauer spectrometry and X-ray diffraction (XRD). The ball milling of Fe-31Cr and Fe-31Cr-12Co mixtures during 3 h results, respectively, in formation of nanostructured (Fe,Cr) and (Fe,Cr,Co) solid solutions with body-centred cubic (BCC) and two metastable paramagnetic structures: face centred cubic (FCC) and primitive cubic (PC). The corresponding Mössbauer spectra present a single-line component relative to the paramagnetic phases superposed to a sextet attributed to a BCC disordered alloy. The analysis of the hyperfine field distribution in terms of Fe atomic surroundings further prove the reality of atomic alloying after this short time of milling. The progress of the milling procedure leads to a very disordered structure of weakly magnetic solid solution. Different fitting procedures have been used to model the structural and magnetic changes.