Ni-coated SiCp reinforced aluminum composites processed by vacuum infiltration

A vacuum infiltration process has been developed to process aluminum-base composites reinforced with particulate SiCp. Electroless nickel coating of SiCp was used to improve wetting by molten aluminum. Experimental results showed that composites of aluminum with 5.9 wt% Si and 0.23 wt% Mg containing about 50 vol% Ni-coated SiCp were completely infiltrated at a temperature above 700 °C. The effects of nickel coating thickness and infiltration temperature on infiltration behavior were investigated. The infiltration rate increased and the infiltration incubation time decreased with increasing infiltration temperature or nickel coating thickness. The microstructure, nickel distribution, bending strength and fracture were also examined. Nonuniformity bending strength and fracture morphology were attributed to nickel macrosegregation.