Characterization of the α-AIFeSi intermetallics by laser scanning confocal microscopy

摘要

As-cast billets of aluminum extrusion alloys of the 6xxxx Al alloys family require a homogenization treatment to make the material suitable for hot extrusion [1]. During this homogenization treatment several processes take place such as the transformation of interconnected plate-like monoclinic β-Al_5FeSi intermetallics into more rounded discrete cubic α-Al_(12)(FeMn)_3Si particles [2-4], the dissolution of Mg_2Si [5-8] and Si precipitates [8] and the precipitation of elements still in supersaturated state [9,10]. Of these processes the phase transformation of the intermetallics and the accompanying shape chape change is deemed to be the most important for obtaining a good extrudability and in particular a good surface quality in the extruded product. However, little microstructural and topological information is available concerning the details of this transformation process and in the absence of such information realistic modelling of the kinetics of this transformation on a physical basis is not possible [11]. To enable the construction of such physical models quantitative information concerning the position of the α particles on the β plates, their 3D shape during early and later stages of growth, and their site density is required.