Foam coating on aluminum alloy with laser cladding

This article concentrates on the creation of a foam layer on an Al–Si substrate with laser technology. The cladding of Al–Si powder in the front of a laser track has been separated from the side injection of mixture of Al–Si/TiH2 powder (foaming agent), which allows for fine tuning of the main processing parameters, i.e., melting temperature and laser processing time. A wide operational parameter window has been found and the formation of a porous layer has been observed for all combinations of Nd:YAG laser power in the range of 1.0–1.5 kW and for scanning speeds between 2.5 and 5.8 mm/s. Microstructural examinations were focused on the study of the relationship between process parameters and foam characteristics (porosity and bubbles size distribution). A tensile test confirmed that due to the relatively low porosity the tensile behavior of the foam layer is closer to the behavior of bulk aluminum than conventional closed cell aluminum foams.