Microstructural aspects of extrusion of rapidly solidified Al–10Mg alloy powder

AbstractThe microstructures of rapidly solidified Al–10Mg alloy powders have been observed by optical microscopy, scanning electron microscopy, and transmission electron microscopy. A technique is described which enabled individual powder particles to be made electron transparent. The alloy powders were then consolidated by cold compaction followed by hot extrusion using a wide range of temperature compensated strain rates. The microstructures evolved are reported and it is shown that there is a correlation between the microstructures and the process parameters. It is also shown that the initial powder structure is an important variable. Magnesium is retained in solid solution in the extrudate but is metastable at room temperature leading to decomposition over long periods of time. However, the very fine grain size observed (1–3 μm) is thermally stable up to 300°C and aging processes may be utilized to obtain acceptable structures.