Fabrication of aluminum alloy foams by using alternative thickening agents via melt route

In our current work, closed-cell A356 aluminum alloy foams were successfully fabricated by using 0.8, 1.0 and 1.2 wt% of barite and wollastonite obtained from the primary minerals processing as thickening agents and calcium carbonate as a foaming agent. The microstructure and mechanical properties of the foams manufactured were analyzed and compared with foams produced with 0.8, 1.0 and 1.2 wt % of alumina and calcium carbonate as thickening and blowing agents, respectively. Foams produced with wollastonite additions showed the highest porosity percent values (86.9%) and cell sizes (0.438 mm) but the lowest energy absorption capacity of (1.58 MJm⁻³). On the other hand, the foams produced with barite additions exhibit a good combination of structure and mechanical properties such as cell size of (0.312 mm), porosity percent (85%) and energy absorption capacity (3.81 MJm⁻³). Foams obtained with alumina additions showed intermediate values of porosities and cell sizes between the foams obtained with barite and wollastonite and the presence of oscillations in the plateau region. The foam obtained with 1 wt % barite showed the highest mean ideality energy absorption efficiency and the longest sustained stage with the smallest fluctuation of the efficiency. The energy absorption efficiency of the foams produced decreases when the porosity and cell size increase. Therefore, the foam produced with barite addition show the best behavior of the energy absorption efficiency, which contributes as a potential thickening agent to the application in engineering field.