Tomographic characterization of copper cellular bodies fabricated by a powder metallurgy route

Abstract

Copper cellular bodies were prepared by powder metallurgy employing carbamide beads as space holders, which were removed by water dissolution before sintering the compact. The method allows for a precise control of the cell characteristics (size, shape and distribution) within an interconnected porosity. Even if the cell walls are well sintered, the use of metal powder promotes the formation of an inherent porosity that affects the mechanical properties of the foam, leading to plastic failure at a low stress. The foam structure characterization was accomplished by x-ray tomography. This technique allows a 3D visualization of the cells distribution, a complete characterization of the cells structure and the evaluation of the sample porosity and connectivity. With the aid of the tomographic slices, we can visually follow the cell walls failure during a compression test, identifying the deformation mechanism. A simple model was validated for the determination of porosity and plastic failure stress.