The cell size reduction of aluminum foam with dynamic gas injection based on the improved foamable melt

Abstract

The reduction of cell size is beneficial to the stability and mechanical properties of aluminum foams. The cell size could be effectively reduced by dynamic gas injection route, but the smaller cell size is also required for the smaller particle size and more uniform dispersion of ceramic particles. The gas injection route and the preparation of foamable melt were both improved in this paper. A self-developed high-speed horizontal oscillation system was used to reduce the cell size of aluminum foam. By controlling the process parameters properly, the aluminum foam with uniform cell diameter about 1mm could be obtained. In order to further obtain more stable and smaller bubbles, the alumina particles with 3.7μm diameter were added into the aluminum alloy melt after ball milling with copper powder or mechanical mixing with aluminum powder. The experimental results indicated that the alumina particles were dispersed uniformly, and the ceramic particles finally distributed around the eutectic region after solidification. The high porosity of aluminum foams can be maintained using dynamic gas injection route based on the improved preparation method of foamable melt, because the cell size is greatly reduced while the cell wall thickness is thinned. The improvement of ceramic particles addition process also reduces the amount of particles on cell walls, which contributes to the mechanical properties of aluminum foam.