Crystalline oxalic acid aided FeAl intermetallic alloy sintering. Fabrication of intermetallic foam with porosity above 45

Intermetallic Fe–Al foam was formed via organic compound assisted sintering. To the starting mixture of iron and aluminum elemental powders various amount of crystalline oxalic acid (COA), (COOH)2•2H2O was added as the foaming agent. Due to the decomposition reaction, gaseous products were formed and behaved as the foaming agents. With this approach Fe–Al intermetallic foam was formed and major role of the COA was confirmed by elemental maps. In the pores, remaining traces of carbon were found. It was also found that at 3wt% of COA additive the greatest porosity equal 48,5%±4,3% was obtained. Above 3wt% the formed foam was defragmenting. Additionally, to investigate functional application of the formed Fe–Al intermetallic foam, the pressure drop of air during penetration the porous material was examined. It was found that increased porosity of the sintered material allowed to increase the flow of the air through the metallic foam. •Crystalline oxalic acid was used during Fe and Al powders sintering.•Highly-porous Fe–Al intermetallic foam was formed.•Traces of carbon were found at pore bottoms.•The more crystalline oxalic acid, the greater porosity, even over 45%.