FRACTURE-BEHAVIOR OF SILICON-CARBIDE FIBER-REINFORCED ALUMINUM-ALLOYS

Silicon carbide fiber (Nicalon)-reinforced aluminum alloys were fabricated by squeeze casting process. The longitudinal flexural strengths were 1. 25 GPa for a pure aluminum matrix, 1. 1 GPa for Al-5%Ni, 0. 75GPa for Al-4. 5%Cu, 0. 43 GPa for Al-3%Si and 0. 25 GPa for Al-5%Mg. For matrices containing Ni, Cu, Si and Mg, the acoustic emission counts were less than for pure aluminum and fracture occurred with fast crack propagation around the maximum stress. Second phase platelets were preferentially crystallized around the fibers and affected the crack propagation. Second phases of whisker-like Al//3Ni in the Al-5%Ni matrix affected propagation to a lesser degree.