Quantitative X-ray diffraction analysis of solute-enriched stacking faults in hcp-Mg alloys based on peak asymmetry analysis

Based on X-ray diffraction analysis we attempt to quantify a volume fraction of stacking faults, which are essentially enriched by solute elements (solute-enriched stacking faults; SESFs) in Mg-Zn-Gd alloys with a hexagonal-close-packed (hcp) structure. We find that the SESFs with a local face-center-cubic stacking mostly occurs as a limited thickness less than several unit-cell dimensions, causing anisotropic broadening of the diffraction peaks including c*-component. By dealing the SESFs as intergrowth-like precipitates, we have successfully decomposed the asymmetric peak profile into the hcp-matrix and the SESF peaks, by which the relevant volume fractions can be estimated in a highly quantitative manner.