Development of Metastable Solidification Structures Using the Electrospark Deposition Process

Electrospark deposition (ESD) was studied to investigate the possibility of forming non-equilibrium microstructures in Al alloy systems. The results have demonstrated that the level of supersaturation is system-dependent. The Al-10 wt% Mg system exhibited a complete supersaturation, while the Al-Si system had a supersaturation level reaching about 1wt%. The ESD process was also used to demonstrate the possibility of forming metastable intermetallics in the Al-Ni system, such as the Al9Ni2. When comparing the present results with the literature of rapid solidification of these alloys using other processes, the discrepancy between the extent of non-equilibrium microstructure obtained is believed to be associated with the formation and duration of the weld pool prior to solidification.