Effects of Mg addition on foam stability of Al foams made by powder metallurgy route

Abstract

Al foams were produced by applying a powder metallurgy route. Foam expansion, cell structures and foam stability of foamed samples were investigated. The results show that larger expansion and more homogeneous cell structures were achieved due to the presence of 1·0 wt-%Mg addition. Mg addition results in the formation of spinel particles through the reaction between Mg powder and alumina on Al powder. Spinel particles show good wetting with Al melt and are fully embedded into Plateau borders and cell walls. The liquid is tightly trapped within cell walls and Plateau borders in the presence of spinel particles, preventing cell walls from thinning further and improving foam stability significantly.