Laser coating of aluminum alloy EN AW 6082-T651 with TiB2 and TiC: Microstructure and mechanical properties

This paper deals with laser coating of ceramics by deposition of a precursor powder mixture of TiB2–TiC–Al on an EN AW 6082-T651 aluminum alloy. The resulting coating was studied by means of a microstructural and mechanical analysis. The coating has with TiC and TiB2 particles of various shapes and sizes embedded in an Al matrix, as well as being adherent and free of cracks with an average porosity lower than 2%. Microhardness in the coating is 40% higher than the uncoated alloy, while the microhardness in the laser melt zone and heat-affected zone dropped significantly. The wear test showed a great improvement in terms of the mass lost after the 30 min test. The three-point bending test was used to determine the flexural properties of the coated aluminum alloy. Higher content of TiB2 in ceramic components increases the flexural strength of the coated specimens, delaying the occurrence of the first crack in the coating or the occurrence of delamination. The measurements of residual stresses confirmed the presence of favorable compressive residual stresses in the surface coating. With depth, these stresses become tensile.