STRUCTURAL TRANSFORMATION OF IRON POWDERS MECHANICALLY PROCESSED IN NITROGEN

Fe-powders mechanically processed in a nitrogen environment were studi ed by means of X-ray diffraction and chemical elemental analysis. Afte r high-energy ball-milling, diffraction spectra exhibited shape modifi cations consistent with the appearance of Fe-bct precipitates within t he Fe-bcc matrix. The bet-phase accumulates monotonously with milling time, constituting a source of inhomogeneous strains in the matrix. De tailed analysis of diffraction spectra allowed the derivation of nitro gen concentrations inside precipitates and matrix grains as well as in the grain boundaries. The results obtained demonstrated for the first time the nitrogen dynamics within a nanocrystalline microstructure at different stages of mechanical processing.