Dislocation loop line density analysis--fundamental differences between TEM and XRD

Dislocation loops in neutron or proton irradiation Zr alloys are usually characterized by TEM. Although X-ray line broadening has proven to be a powerful tool for determining dislocation densities (DD) in deformed materials, in irradiated materials X-rays usually give larger DDs than TEM analysis. MD simulations also showed larger loop densities in ion irradiated Cu and W than detected by TEM suggesting that, while the smallest loops remain undetected by TEM, loop size-distribution can be well approximated by a power-law function. Based on these results we developed a method to determine exponential loop size-distribution functions for neutron and proton irradiated Zr alloys by combining X-ray and TEM DD data. This concept helps to explain inconsistency when comparing TEM and X-ray DD analysis, which is related to the very small irradiation-induced loops missed by TEM analysis.