Weld structure of joined aluminium foams with concentrated solar energy

•We present an alternative to laser welding of aluminium foam plates. Solar concentrated energy allowed larger surfaces to be joining.•Mechanisms of filler expansion and welding defects are discussed.•It is overcome the limit plate thickness using a second run. Concentrated solar energy was applied to welded foam plates in non-protective atmosphere. The filler was a pore-generating aluminium–silicon alloy placed between two commercial aluminium foam plates. The heating device provided enough energy to melt and foam the filler. The heat affected surfaces on foam plates and welding mechanisms were correlated with heating conditions. Test plate thickness controlled filler foaming, and two runs were necessary to complete foaming. Weld characterization through tensile tests and microstructural study was performed. The role of the oxide layer on the weld was analyzed and the main welding mechanisms identified: a mechanical form-fit and a metallurgical connection.