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

Mechanical alloying (MA) of Fe1-xCrx powder mixtures was performed over a w ide range of concentration. Both x-ray diffraction and TEM analyses show th at, after 30 hours of milling, the powder particles consist of nanocrystall ine grains less than 10 nm in size. The kinetics of mixing is studied by Mo ssbauer spectrometry. This is the first time that the FeCr mixing state has been studied as a function of the milling conditions and the initial powde r composition. This mixing state is defined by a parameter (d) calculated f rom the hyperfine field values. The alloying process is weakly composition dependent(for x less than or equ al to 40 at.% Cr), but is linked to the energy input to the powder. Especia lly an energy threshold must be transferred to the powder to reach a comple te 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 homoge neous in composition and have hyperfine parameters close to those of the bu lk alloys.