Laser surface treatment of aluminium matrix composites

Absorptance is the base parameter that is determining the energy coupling of a laser radiation into workpiece during its laser treatment. The absorptance for AlSi12/SiC p composites along with their temperature's dependence for the AlSi12 alloy matrix and for wavelengths that correspond to DL, Nd:YAG and CO 2 lasers were investigated. Based on the absorptance, the characteristic laser energy densities at which the surface of the metal matrix composite reaches melting temperature were estimated. This estimation was crucial in order to find the bottom level of energy densities, i.e. operational parameter window for AlSi12/SiC p laser melting. Using higher energy densities than the characteristic the surfaces of the AlSi12/SiC p were remelted. In this process the industrial Diode and Nd:YAG lasers were used. Laser remelted composites were subjected to methods of XRD, hardness and residual stress tests. The tests showed that the control of the laser energy density during the laser treatment of the AlSi12/SiC p allowed to obtain a refine structure of the composite matrix. This refine structure is advantageous for the improvements in hardness and corrosion-resistant of the investigated AlSi12/SiC p composite surface.