| Popis: |
Solid state reactions during mechanical alloying (MA) in a binary mixture of powdered Cr and 57Fe in atomic ratio of 99:1 have been studied using 57Fe Mossbauer spectroscopy, X-ray diffraction and Auger spectrometry. The proposed model of MA includes formation of Cr(Fe)xOy oxides at the contact places of Cr and Fe particles, formation of nanostructure with simultaneous dissolution of the oxides, penetration of Fe atoms along grain boundaries in close-to-boundary distorted zones of interfaces in a substitutional position, formation of the substitutional solid solution of Fe in Cr in the body of grains. It was shown that the increase in the BCC lattice parameter on increasing the milling time is due to the dissolution of oxides and formation of interstitial solid solution of O in Cr. There were established substantial differences in consumption of BCC Fe in a Mg → Al → Si → Cr sequence due to the major role of chemical interaction of Mg(Al,Si,Cr) with Fe. |
