THE STRUCTURE AND PROPERTIES OF AL-4.5CU ALLOY REINFORCED WITH CARBON-FIBER

The solidification processing of metal matrix composites has a strong influence on their mechanical properties. In the present work, the eff ect of the solidification cooling rate on the solidification microstru cture, microsegregation, and mechanical properties of carbon fiber (CF )/Al-4.5Cu metal matrix composites was investigated experimentally. Th e results show that, during the solidification processing of squeeze c ast CF/Al-4.5Cu composites, the alpha-Al phase nucleated first in the interstice region in the fiber. When the solidification cooling rate w as decreased, the crystalline quantity of theta-Al2Cu phase in the int erface region decreased and its shape was changed from a large block-l ike to particle-like crystallites. The microsegragation of the Cu elem ent also decreased, but the bending strength of the composites increas ed. In addition, because the fiber-metal interface was strongly bonded in the CF/Al-4.5Cu composites, the fracture surface of the composites showed the characteristics of brittle fracture. No fiber pull-out was observed in any of these composites.