Characteristics of Pore Morphology in Aluminum Alloy Foams Fabricated by Semi-Solid Route among Multiple Experimental Runs

Abstract

A semi-solid route is expected to be a fabrication method that can fabricate aluminum alloy foams with a variety of mechanical properties, but the allowance fluctuation of the fabrication conditions of aluminum alloy foams with high reproducibility is not clear. The objective of this study was to reveal the allowance fluctuation between the setting temperature and the actual temperature of the melt to fabricate stable foams, having pores with small pores and high circularity, and the influence of the increasing volume fraction of the solid on the pore morphology. Al-Si alloy foams were fabricated five times by adding a blowing agent into a semi-solid slurry under the same setting fabrication conditions, such as the temperature and concentration of oxygen in the atmosphere. The results of small relative standard deviations of pore diameter and circularity indicated that the conducted fabrication process had high reproducibility, even if the volume fraction of the solid changed in a range of 5%. When the volume fraction of the solid exceeds the minimal fraction of primary crystals for prevention of drainage, the clogging effect works more efficiently because the ratio of clogged cell walls increases. Additionally, the preferred range of the volume fraction of the solid for the fabrication of stable foam was revealed to be around 15% to 35%.

Pore Structure and Deformation Correlation of an Aluminum Foam Sandwich Subject to Three-Point Bending

“…The pores were distended because of their being filled by hydrogen, but the growth was restricted by gravity drainage under molten conditions and the surface tension of the melt [1]. Due to the shrinking core mechanics driving the TiH 2 decomposition process, the rate of expansion of H 2 decreases in time [42], so pores grow rapidly in the initial stage by the decomposition of TiH 2 . As the pores nucleate and grow rapidly, the foaming process reaches the growth stage and the rate of release of H 2 decreases.…”