A study on aluminum–steel composite metal foam processed by casting

Composite metal foam (CMF), a new material belonging to the class of advanced cellular and porous materials, has been processed using gravity casting technique for the first time at North Carolina State University. This material comprises of steel hollow spheres and a solid aluminum alloy matrix. The energy absorption behavior of the material under static compression has been studied extensively. Experimental results show that CMF not only has a higher energy absorption capability than that of other commercially available metal foams produced from similar materials, but also possess a higher strength to density ratio. The microstructural analysis of the material was used to study and explain the formation of different phases at the aluminum–steel interface and their effect on the deformation behavior of the foam under compression. As the result of high strength and strain rates, the increase in energy absorption of the composite metal foam samples observed ranges over 30 times compared to that of 100% Al foams and over twice compared to that of 100% steel foams.