Processing and simulation for consolidation of nanostructured Al-Cu powder alloys

Nanostructured aluminium-based alloys are light yet much stronger than conventional materials, which offer technological opportunities for applications such as in aerospace industry. One of the alloys of great interest for such applications is based on Al-Cu system and one of the main challenges for development of such alloys are associated with powder processing. However, processing such powder alloys into bulk material requires relatively low temperature and high pressure, which presents significant processing difficulties. A two-step approach is being explored in our group to reach the goal of a fully dense bulk material. Firstly, cold pressing is used to partially consolidate the powder material and secondly, hot extrusion is used to consolidate the alloy to full density. Process modelling is being used to design the extrusion process, including the extrusion ratio and extrusion length, to limit the temperature increase during extrusion as a result of adiabatic heating, and to avoid excessive heating to limit the undesirable grain growth of the material. A parametric study of extrusion parameters is presented and processing parameters are recommended. The use of process modelling has proven to be a useful tool in understanding the results from the extrusion experiments and limiting the number of interactions during extrusion.