Cellular structure and energy absorption of Al Cu alloy foams fabricated via a two-step foaming method

Two-step foaming (TSF) method is one of cost-effective ways to prepare shaped, closed-cell Al alloy foams with a thick surface layer, which can provide good energy absorption property. In this study, we designed 27 groups orthogonal experiments based on Taguchi method to investigate the effects of key processing parameters on the closed cellular structure of AlCu alloy foams fabricated via the TSF method. The compressive behavior and energy absorption of the fabricated foams were also evaluated and compared with samples prepared by powder metallurgy method (PM). The results showed that processing parameters such as the holding time, foaming temperature and their mutual interaction during the second foaming could affect the final cellular structure features, such as porosity content, average diameter, pore distribution uniformity and sphericity. Quantitative analysis indicated that a shorter holding time (<5 min) and higher foaming temperature (>760 °C) could fabricate AlCu alloy foams with descent cellular structure and energy absorption capability.