The influence of pre-milling on the microstructural evolution during mechanical alloying of a Fe50Cu50 alloy

Abstract

Fe50Cu50 solid solutions have been obtained by two different mechanical alloying routes, i.e. from Fe-Cu powders with and without premilling. These two alloying processes were studied and compared at two rotation speeds of a planetary ball-mill, namely 200 rpm and 300 rpm. The microstructural evolution of the ball-milled powders as a function of milling time was monitored using electron probe microanalysis, X-ray diffraction, scanning electron microscopy and Mössbauer spectroscopy. In both processing routes, a broad distribution of different local environments of the iron atoms was observed in the Mössbauer spectra of the fcc-FeCu phase. Mössbauer spectra show further that a fcc non magnetic Fe-rich phase is formed transiently besides the bcc-Fe phase. The Fe-Cu reactions are slowed down when premilled powders are used as starting powders but similar fee solid solutions are formed during milling. As expected, the mechanical alloying process is faster at 300 rpm but the final results are similar using 200 rpm or 300 rpm.