Production of aluminum-SiC composite using sodium tetrasborate as an addition agent

The process for introducing particulate silicon carbide into molten aluminum or aluminum alloy which comprises mixing particulate silicon carbide from the group consisting of particles having an average size of about 5 to about 70 microns and fibers having an average diameter of about 0.1 to about 15 microns and a length of about 10 microns to about 5 centimeters with a dehydrated addition agent of sodium tetraborate in weight proportions of 1:1 to 2:1, introducing the resulting mixture into an aluminum or aluminum alloy bath at a temperature above the liquidus temperature of the bath in an amount of about 5% to about 40% of silicon carbide, by volume of said bath to disseminate said silicon carbide particles throught said bath and solidifying said bath to produce a composite material reinforced with silicon carbide particles or whiskers distributed in a matrix of aluminum or aluminum alloy.