COMPARISON OF FIBERS FOR CREEP STRENGTHENING OF ZINC-ALUMINUM FOUNDRYALLOYS

A comparative evaluation is made of a variety of possible fibrous rein forcements for strengthening zinc-aluminium foundry alloys. The compos ites are processed by squeeze casting, using preforms of alumina, carb on, stainless steel or low carbon steel fibres. A drastic improvement of the creep strength is achieved with the use of alumina or steel fib res. However, an acceptable level of fracture toughness is maintained only in the composites reinforced with steel fibres. This property res ults from the low interface adhesion which allows bridging of the crac k. by the fibres. Low carbon steel fibres do not exhibit more interfac e reaction than stainless steel fibres. It is concluded that low carbo n steel fibres provide a better compromise when taking into account th e creep strength, the fracture toughness and the cost of the composite .