Research On The Microstructures And Mechanical Properties Of The Al-Cu Alloys Fabricated By The Solid-Liquid Mixed Casting Technology

The microstructures and mechanical properties of Al-Cu alloys fabricated by a bran-new technology—solid-liquid mixed casting (SLiM casting) was studied in this paper. The technics of the SLiM casting was conformed based on the known results. And the Al-Cu ingots were fabricated successfully by the technology. The microstrutures and mechanical properties of Al-20Cu alloys, Al-40Cu alloys and Al-65Cu alloys produced by the SLiM casting were investigated by DSC, tensile strength test, OM and SEM. The refining mechanism of the microstructures was analysised in the processing. In addition, the pilot study about the wear resistance of Al-40Cu alloys was discussed.These researches indicate: the microstructures of Al-Cu alloys produced by SLiM casting were finer; the mechanical properties of Al-Cu alloys at room temperature were better. Otherwise, the finer the added powders, the smaller the grain size of the SLiM casting alloys, the higher the mechanical properties at room temperature. Better extrudability and abrasive resistance at room temperature can also be obtained by the processing. So this technology has its advantages, and can be applied in some fields.The shape of α-Al in Al-20Cu alloy fabricated by conventional casting was dendrite. When the alloy was prepared by SLiM casting, these a-Al presented rosette or net-globoid. And the average size of the a-Al was approximately 70μm (added 200-96μm powders) or 50μm (added 74-43μm powders), which was obviously smaller than that of the Al-20Cu alloy made by semi-solid casting (120μm). The shape of θ_I (CuAl₂) in Al-40Cu alloys prepared by solid-liquid mixed casting was rounder than others. The average size in length was decreased from 500μm (conventional casting) to 100μm (added 200-96μm powders) or 80μm (added 74-43μm powders); the average size in width was decreased from 80μm (conventional casting) to 40μm (added 200-96μm powders) or 30μm (added 74-43μm powders); the length-width ratio was reduced from 6 to 2.5. The microstructures of the Al-65Cu alloys prepared by the SLiM casting were composed of 0 and η₂ which shapes presented rosette or globoid with the average size below 35μm, which was obviously smaller than that of the semi-solid casting (100μm).Through the SLiM casting, the room temperature mechanical properties of the...