Review of the techniques for the extraction of second-phase particles from aluminum alloys

This article briefly reviews the methods developed for extracting the second-phase particles from aluminum alloys. The chemical phenol extraction technique has been compared with the electrochemical potassium iodide (KI)-in-methanol method for two heat-treatable 6000-series alloys. It is demonstrated that by carrying out the centrifuging warm in the phenol method, the technique can handle quite large sample sizes without contamination and regardless of the heat-treated condition of the sample under examination. In contrast, the KI-in-methanol method is limited to homogenized materials. The phenol particle extraction from high-Cu (< 1.0%)-containing alloy showed contamination arising from the metallic Cu that appears to originate from the Cu in the matrix, rather than from Cu-containing second-phase particles.