The distribution of components, or microstructure, within a material is critical to its mechanical properties. For example, if a material has too many particles of one particular phase it may become too brittle, yet if there are too few particles it could lose strength. Every material exhibits different and unique characteristics. The goal of a material scientist is to analyze a material's microstructure and to optimize the manufacturing process. Electron microscopists observe this distribution on a very small, but critical, scale. The electron microscope can demonstrate specifically where the particles are distributed and then X-ray microanalysis can be used to identify what the particles are composed of.

This article will discuss the microstructure of an aluminum alloy with copper and iron additions. At the point of development, the mechanical properties of this new alloy were believed to be superior to that of previous materials; however, a number of subsequently conducted heat treatments did not support this theory, producing extremely unsatisfactory properties. In order to understand these results and rectify any problems, X-ray microanalysis was used to analyze the alloy's microstructure and assess the distribution of copper and iron particles within the metal.