Dislocation structure and crystallite size distribution in plastically deformed Ti determined by X-ray peak profile analysis

Ultrafine-grained titanium produced by equal channel angular pressing and subsequent cold rolling is studied by Xray diffraction. It is found that a texture exists in which the hexagonal basal planes are parallel to the longitudinal axis of the billet. The crystallite size distribution and the dislocation structure are determined by X-ray diffraction peak profile analysis. The median and the variance of the crystallite size distribution are obtained as m = 39 nm and sigma = 0.14, respectively. The dislocation model of anisotropic broadening of peak profiles enables to determine the active slip systems. It was found that all three possible hexagonal Burgers vectors of dislocations exist, with the composition of 66% <a> type, 33% <c> type and 1% <c + a> type.