Investigation of sintered and laser surface remelted AlSiC composites

The present work focuses on the microstructural characterisation of aluminium-base ceramic particle reinforced composites produced by powder metallurgy. Powder mixtures containing different quantities (5, 10 wt.%) and grades (F500, F800) of SiC particles as reinforcement constituents were uniaxially cold pressed. Afterwards the green compacts were sintered in a high purity nitrogen atmosphere. Dimensional changes of specimens occurring during sintering were controlled by dilatometry. Porosity measurements were performed on the polished cross-sections of sintered probes by an automatic image analyser. Laser surface treatments were also carried out on the sintered materials. The surfaces of the specimens were remelted using industrial CO2 laser equipment to achieve compacts with low porosity surface layer. The effect of laser-beam power, of amount and grain size of SiC particles on the remelting process and on the microstructure evolution was investigated.