Improvement in energy absorption properties of aluminum foams by designing pore-density distribution

Abstract

In the present work, effect of structural design on the mechanical properties of aluminum foams was studied. Aluminum foams with a relative density in the range of 0.28–0.48 with uniform and graded pore frequency were fabricated through powder metallurgy route by using carbamides as space holder, where double action die pressing process was used for producing green compacts. Carbamide space holders were removed by leaching in water plus heating processes, whereafter the samples were sintered at 640 °C for 2 h in air. Mechanical properties and energy absorption capability of the fabricated foam samples were evaluated by the means of compression test. The results showed that correct modification in pore distribution can significantly improve mechanical properties of the fabricated foam by compensating the undesirable density gradient created in the foam structure due to the die wall friction. So that for the foams with a relative density of 0.28, introducing desired gradation in pore frequency caused nearly 100% increase in plateau stress and more than 75% improvement in energy absorption ability of the fabricated foam.