Evolution of the statistical properties of dislocation ensembles

X-ray line profile analysis is an efficient non-destructive technique to determine some key statistical properties of dislocation structures developing during plastic deformation. In the first part of the paper recent developments describing the asymptotic behavior of the line profiles are outlined. A new evaluation method is presented to determine the average dislocation density and its spatial variation. The method is demonstrated on measurements obtained on compressed Cu single crystals. After this, it is shown that the relative dislocation density fluctuation exhibits a sharp maximum at the stages II-III transition. A nanoindentation tests indicate that the fluctuations of other quantities behave similarly. The results give new insight into the dislocation phenomena taking place in the stage III deformation regime.