X-ray diffraction line broadening analysis of nanostructured nickel powder

Abstract

X-ray diffraction peak profile analysis is a powerful method for investigation of the microstructural characteristics of nanocrystalline materials produced by severe plastic deformation. Williamson–Hall method, its modification, and Fourier transform methods like Warren–Averbach and its modification are used to extract microstructural information based on integral breadth and Fourier coefficients of the peak profiles. In this work, pure nickel powders were milled for 2, 5, 20, and 40 h to clarify the microstructural variations for this metal with FCC atomic structure. By using the Williamson–Hall and Warren–Averbach methods and their modifications, crystallite size, microstrain, dislocation density, and character of dislocation were extracted. It was obtained that the fraction of edge-type dislocation decreased with milling time (above 50%), while after prolonged milling, the fraction of screw-type dislocations decreased, so that 50%-edge-to 50%-screw ratio was obtained. It was also found that the values of the crystallite size obtained from classical Warren–Averbach and modified Warren–Averbach (area-average) were closed.