Foaming stabilization and mechanical properties of high-toughness aluminum foam fabricated using non-thickening foaming technology

The brittle failure of aluminum foam limits its potential applications. To overcome this shortcoming, this study focused on a non-thickening foaming technology for fabricating the high toughness aluminum foams, in which a foaming mixture (FM) was directly mixed into a pure aluminum melt without any thickening process. The thermal analysis revealed that the physical encapsulation generated during the ball-milling process of FM delayed the severe decomposition of TiH2. The changes in the FM composition affected the total foaming height and thickness of the bubble-free layer. The aluminum powders in FM played a key role during the foaming process by: i) acting as a transient thickening agent during the mixing process, thus, increasing the melt viscosity, and ii) attaching to the bubble surface, thus, hampering the liquid film thinning process and improving the stabilization. As a result, the unmelted aluminum powders were retained on the pore surface. The bending analysis revealed that the as-obtained foamed aluminum possessed high bending toughness and energy absorption. The strain at σmax was noted to be nearly 100 % higher than that of the traditional aluminum foam. Further, large dimples coupled with an obvious necking phenomenon were observed on the cracked pore wall.