Recent Progress of Line-profile Analyses for Neutron or X-ray Diffraction

Abstract

Several methods on single-peak and multi-peaks line-profile analyses for neutron or X-ray diffraction are critically reviewed. Compared with deconvolutional methods like the classical Williamson-Hall method and the modified Warren-Averbach method combined with the modified Williamson-Hall plot, a recently developed convolutional multiple whole profile (CMWP) fitting method enables to provide the density, arrangement and character of dislocation and crystallite size reasonably. Elasto-plastic deformation behavior in austenite, ferrite, martensite and two-phase steels are studied using such profile analyses, revealing that flow stress is dependent not only on dislocation density but also its arrangement. In particular, in situ neutron diffraction with the CMWP analysis is powerful to monitor microstructural changes during deformation and/or heat treatment. For the evaluation of crystallite or grain size, diffraction, small angle scattering and Bragg edge imaging should be employed taking their applicable length scales into consideration.