Grain core study of Fe1-xCrx nanograins obtained by mechanical alloying

Mechanical alloying (MA) of Fe1-xCrx powder mixtures was performed over a wide range of concentration. Both x-ray diffraction and TEM analyses show that, after 30 hours of milling, the powder particles consist of nanocrystalline grains less than 10 nm in size. The kinetics of mixing is studied by Mossbauer spectrometry. This is the first time that the FeCr mixing state has been studied as a function of the milling conditions and the initial powder composition. This mixing state is defined by a parameter (d) calculated from the hyperfine field values. The alloying process is weakly composition dependent(for x less than or equal to 40 at.% Cr), but is linked to the energy input to the powder. Especially an energy threshold must be transferred to the powder to reach a complete alloying. By studying the hyperfine field distributions of the Mossbauer spectra (for Cr < 40 at.%), it seems that the Fe1-xCrx nanograin cores are quite homogeneous in composition and have hyperfine parameters close to those of the bulk alloys.