On the validity of simple precipitate size measurements by small-angle scattering in metallic systems

This paper assesses how simple small-angle scattering particle size evaluation models, such as Porod or Guinier radii, which have a normally limited validity range, may see this range extended to larger q values. This is shown to be particularly true for metallic systems, where the dispersion in particle size is always large. Because of the size dispersion, the relationship between the average particle size and the Guinier radius is shown to change. For systems with relatively large size dispersion, the paper shows that the Porod and Guinier radii, and simple extensions thereof, give valuable information on particle size and particle size distribution. This is demonstrated to be valid for particles with moderate aspect ratios. These simple evaluations are quick and very well adapted to large data sets, such as those originating from time-resolved or scanning small-angle experiments.