High-strength 7xxx series aluminum alloys have great potential in automobile lightweighting. However, these alloys are difficult to extrude in complex geometries. Adaptation of alloy compositions and process parameters, such as homogenization regimes, can improve extrudability, but also influence final product properties.

The focus of this work was to optimize the extrudability of an EN AW 7108A by adjusting the Zn and Mg contents and enhance the precipitating of nanoscale Al3Zr-dispersoids through different, shortened homogenization regimes. For this purpose, experimental alloys were continuously cast, homogenized and extruded at laboratory scale, and analyzed using various methods. Scanning electron microscopy (SEM) investigations were carried out to analyze the dispersoid phases. A novel detector for low-energy backscattered electrons (Gatan OnPoint BSE detector) was used, which allows for quantification of nanoscale dispersoids in SEM at low accelerating voltages (<5kV) and, thus, increased resolution. The results were validated by transmission electron microscopy (TEM) measurements.

We report optimized Zn and Mg contents for extrusion and a fast quantification method of nanoscale Al3Zr-dispersoids in aluminum alloys to quickly analyze different homogenization variants for further optimization and improved extrudability, without costly and time-consuming TEM studies.