Study On The Mechanism Of Solidification Under Ultrasound Conditions Of ZL201 Alloy

ZL201 alloy has a wide crystallization range and large shrinkage,which is easy to produce casting defects such as shrinkage,shrinkage,crack and segregation.In this paper,power ultrasonic treatment is applied to the solidification process to improve its casting properties.The paper firstly based on the material properties of ZL201.The characteristics of power ultrasonic treatment of metal melt design and build alloy smelting-ultrasonic treatment-flip casting-static solidification flow ultrasonication test platform,then use orthogonal test method to design and optimize ultrasonic solidification test.By means of optical microscopy Technology（OM）,Electron Scanning Microscopy（SEM）,Energy Analysis（EDS）,Microscopic Quantitative Analysis,Density Testing,Conductivity Testing,Brinell Hardness Testing,and Tensile Testing,the grain fineness number and mesophase content,physical and mechanical properties of ZL201 alloy were measured and analyzed.The ultrasonic solidification process parameters and mechanical properties were further discussed.Quantitative relationship between microstructure and properties of materials reveals the mechanism of ultrasonic solidification.The results show that:（1）Crystallization reaction L→α+θ occurs during cooling of ZL210 alloy.The microstructure of ZL201 alloy is mainly composed of α-Al,θ-CuAl₂ and TiAl₃.Ultrasound treatment can reduce the size and content of θ-CuAl₂ phase in varying degrees.With the increase of ultrasonic power,which improves the effect of solid-solution strengthening,the solid-soluble Cu element in α-Al matrix increases gradually,and θ-CuAl₂ phase is refined and the content of θ-CuAl₂ phase decreases.（2）The optimum processing parameters of ZL201 alloy were obtained by range analysis method in orthogonal test when the ultrasonic vibration temperature was 640℃,the applied power was 1000W,the applied time was 30s,and the applied depth was 65mm.（3）Ultrasound treatment has an effect on the physical and mechanical properties of ZL201 alloy.Ultrasound cavitation bubbles take the gas from the melt away from the alloy liquid,which affects the density of ZL201;Ultrasound treatment increases the solid solubility of Cu in Al matrix,which affects the conductivity of ZL201;Ultrasound treatment improves the effect of solution strength of Cu in Al matrix,which affects the Brinell hardness of ZL201;Ultrasound treatment decreases grain sizes and increases the density of grain boundaries,which affects the tensile properties of ZL201.（4）The tensile fracture mode of ZL201 alloy is quasi-cleavage transgranular fracture,intergranular fracture and dimple fracture,which is due to the fine and uniform microstructures obtained by ultrasonic treatment during solidification.This fracture mode ensures the excellent tensile properties of ZL201 aluminum alloy.