Density-graded cellular aluminum

Open-cell metallic foams with controlled, continuous density gradients were created from polyurethane foam precursors using an investment casting method. This method, designed to improve mass-efficiency in load-bearing metallic foams and facilitate bonding of foams to dense materials in higher-order structures, is described in detail, and demonstrated through pure aluminum foams with model relative density gradients. Methods for structural characterization, including non-destructive local density mapping, are also illustrated.