Fluidity And Filling Ability Research Of Zr-based Bulk Metallic Glass Melt

Bulk metallic glass has excellent mechanical properties such as high strength, high elastic limit, good wear resistance and corrosion resistance and lower thermal expansion coefficient and small casting solidification shrinkage rate which show important potential applications in the field of aerospace and defense equipment and others. However, bulk metallic glass cannot be rolled or forged. The forming technology trail of bulk metallic glass limits the application in the industrial field. The usefulness of alloy melt flow casting molding is the most possible way to achieve inexpensive technologies for processing.In this paper, two kinds bulk metallic glass Zr41.2Ti13.8Cu12.5Ni10Be22.5(Vit 1) and Ti32.8Zr30.2Cu9Ni5.3Be22.7(ZT3) which possess relatively strong glass forming ability were chosen to be the experimental materials. Two kinds mold materials- industrial copper and high purity graphite were used to design and manufacture two different size mold cavity. Different experimental parameters such as superheat temperature and pouring height were chosen for two bulk metallic glass melt, and volume flow was used to evaluate the fluidity and filling ability of melt. Based on the theory of casting forming and heat transfer and on the basis of the constitutive equation of crystal alloy volume flow, an improved equation for characterizing bulk metallic glass melt volume flow was constructed. The structure of samples was identified by X-ray diffraction(XRD) and thermal parameters of samples were examined by differential scanning calorimeter(DSC). The compression performance of bulk metallic glass under different experimental conditions at room temperature was tested by Instron universal material testing machine and the fracture morphology of sample was observed by SEM.The results show that the volume flow in the mold cavity of two kinds bulk metallic increases with the increasing superheat temperature and the cross-sectional area of flow path. By increasing the pouring height, the filling speed and melt volume flow can be improved and there is a linear relationship between the volume flow and pouring height. Comparing the flow characteristic of bulk metallic glass in industrial copper and high purity graphite, we can found that under the same casting conditions, due to the difference of coefficient of heat storage of two molds, the alloy melt volume flow is also different. The volume flow in high purity graphite mold is significantly larger than that in industrial copper mold, at the same time the melt volume flow in high purity graphite mold is more sensitive to the change in height.Comparing the mechanical properties of two kind bulk metallic glass under different casting conditions, we can found that the mold materials and dimension of mold has no significant effect on the mechanical properties of two bulk metallic glass of Vit 1and ZT3, but ZT3 exhibits a small amount of plastic deformation.