【作者】 黄雅妮；

【导师】 高文理；

【作者基本信息】 湖南大学 ， 材料加工， 2006， 硕士

【摘要】 本论文主要研究利用一种新型的材料制备方法——固液混合铸造制备的Al-Cu合金的组织和性能。根据已有的研究结果制定了固液混合铸造Al-Cu合金的工艺并成功的制备了Al-Cu合金铸坯。通过DSC分析、力学性能测试及OM、SEM形貌分析等手段对固液混合铸造Al-20Cu合金、Al-40Cu合金、Al-65Cu合金的组织和性能进行了研究；分析了固液混合铸造工艺中，合金组织的细化机理；对固液混合铸造Al-40Cu合金的摩擦磨损性能进行了初步研究。 研究结果表明：固液混合铸造工艺明显细化Al-Cu合金的组织，提高Al-Cu合金的室温力学性能。加入的粉末颗粒越细，材料的组织越细小，室温力学性能越好。固液混合铸造浆料具有良好的挤压性能，挤压坯料具有良好的室温耐磨性能。该工艺具有一定的先进性和优越性，存在一定的工业应用前景。 普通铸造时，Al-20Cu合金的初生α-Al为树枝状。固液混合铸造Al-20Cu合金的初生α-Al为蔷薇状或近球状，其大小可以达到70μm（加入200-96μm粉末）或50μm（加入74-43μm粉末），明显小于半固态加工的120μm。固液混合铸造Al-40Cu合金初生θ相更为圆整。长度方向的平均尺寸由普通铸造500μm减至100μm（加入200-96μm粉末），或80μm（加入74-43μm粉末）；径向的平均尺寸由普通铸造80μm减为40μm（加入200-96μm粉末），或30μm（加入74-43μm粉末），长径比由普通铸造的6减至2.5。固液混合铸造的Al-65Cu合金的显微组织主要由蔷薇状、近球状的θ相和η₂相组成，晶粒尺寸为35μm以下，明显小于半固态铸造的100μm。 在固液混合铸造工艺条件下，Al-20Cu合金的室温力学性能为：σ_b=165MPa，σ_0.2=100MPa，δ=2％（加入200-96μm粉末）；σ_b=193MPa，σ_0.2=116MPa，δ=3％（加入74-43μm粉末）。Al-40Cu合金的室温力学性能为：σ_b=187MPa，σ_0.2=113MPa，δ=1.5％（加入200-96μm粉末）；σ_b=209MPa，σ_0.2=125MPa，δ=2％（加入74-43μm粉末）。固液混合铸造Al-40Cu合金的质量磨损量为12.3mg，其主要的磨损形式是粘着磨损、疲劳磨损和磨粒磨损。更多还原

【Abstract】 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更多还原