| High nitrogen face-centered-cubic(f.c.c.) metastable phase formed on the nitrogen-modified Fe-Cr-Ni austenitic stainless steels at low process temperature,which is named byγN phase,has a combined wear and corrosion resistance.X-ray diffraction(XRD) patterns of theγN phase on the stainless steels depict a set of broad and asymmetry diffraction peaks with a peak shift to low Bragg angles and a decrease of intensity,even disappearing of some peaks of high-index planes,from each austenite peak for theγmatrix.The peak shift of the XRD patterns of theγN phase was explained by Warren's peak shifts' equation.X-ray diffraction analysis is applied to unambiguously study the structural characteristic of theγN phase and further to assess the effect of stacking faults on the XRD line profiles.In this paper,a systematic study of x-ray diffraction on the peak shift,peak asymmetry,peak broadening and peak intensity of theγN phase has been performed based on a fault-induced scattering geometry in diffraction to imperfect f.c.c,crystals by Warren's theory and Wagner's method.A model of x-ray diffraction line profiles of theγN phase has been proposed,which further proves that theγN phase can fit to a structural model of an f.c.c,phase with a high stacking faults density.Both the higher deformation faults density(α) in a range of 0.02-0.25 and the lower twin faults density(β) of 0.01-0.1 are successfully used to describe the line profiles in XRD patterns of theγN phase formed on the nitrogen-modified Fe-Cr-Ni austenitic stainless steels at low process temperature.A novel stacking faults factor Sαβ dependent onαandβdescribes in good agreement the peak intensity of theγN phase.The calculated XRD patterns of theγN phase using the imperfect crystals model of an f.c.c,phase with a higher deformation faults density and a lower twin faults density are associated with the experimentally structural characteristics.
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