Microstructure evolution and mechanical properties of Al-Al2O3 composites fabricated by selective laser melting

The promising selective laser melting (SLM) technology was introduced to prepare Al based composites reinforced by Al2O3 particles. The influence of SLM processing parameters on the densification behavior, microstructure, microhardness and resultant wear performance was studied in detail. The results revealed that the near fully dense composite part (973% theoretical density) was achieved with the optimized v of 550 mm/s applied. A proper decrease in the applied v to 550 mm/s was proved feasible to favor the Al2O3 particle dispersion homogeneity due to the trapping effect of Al2O3 particle with the advancing interface in the molten pool. Besides, a continuous and compatible interface was developed in this case. At an even lower v of 450 mm/s, the homogeneously dispersed Al2O3 reinforcements exhibited a novel ring structures along the boundaries of molten pool, but showing a significant coarsening morphology. The optimally prepared fully dense Al-Al2O3 composite part exhibited excellent hardness with a mean value of 175 HV0.1 and superior wear performance with a considerably low coefficient of friction of 0.11 and a significantly reduced wear rate of 4.75 x 10(-5) mm(3) N-1 m(-1).