Effect of cell size on the response to solution and aging heat treatments of open-cell Al-4.5Cu (wt.%) foams

Abstract

Open-cell Al-4.5Cu (wt.%) foams were produced by the replication casting technique in cell sizes of 2.00–2.38 and 3.35–4.75 mm. The fabricated foams were subjected to solution and aging treatments to assess the effect of such heat treatments on the microstructure and mechanical properties of the foams as a function of cell size. Solution and aging heat treatments were carried out at 535 °C for 5.5 h and 170 °C for 8 h, respectively. The porosity and relative density of all produced samples were estimated by He pycnometer. In addition, the average cell wall thickness was assessed by image analysis to correlate this variable with the response to heat treatments of the material. The microstructural evolution of the heat-treated samples was analyzed by means of scanning electron microscopy, scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and differential scanning calorimetry. The mechanical characterization of the studied samples was carried out using uniaxial compression tests and microhardness tests. It was found that the foams did present different responses to both solution and aging treatments as a function of cell size, attributing these outcomes to the cell wall thickness variations, which presumably conditioned the cooling rates after heat treatments, thereby influencing the resulting microstructures and precipitation of Al-Cu second phases. Graphical abstract