Rapid Solidification Of Ag-Cu-Sb Ternary Eutectic Alloy

The present thesis carries out detailed investigations on the phase constitution of Ag42.4Cu21.6Sb36 ternary eutectic alloy and other Ag-Cu-Sb alloys with relevant compositions. The rapid solidification process of Ag42.4Cu21.6Sb36 ternary eutectic alloy was realized by glass fluxing, drop tube and melt spinning methods. And the influence of experimental conditions on solidification process was studied in details.The phase constitution of Ag42.4Cu21.6Sb36 eutectic alloy and other Ag-Cu-Sb alloys was determined by X-ray diffraction. Experiments show that the solidified microstructures of Ag42.4Cu21.6Sb36 eutectic alloy and those alloys with vicinal compositions consist of 9-Cu2Sb, (Sb) and e-AgsSb phases. Based further on the phase constitutions of AgeoCu20Sb20 and Ag60CueSb34 alloys and the growth characteristics of these alloys, it is inferred that the current phase diagram of Ag-Cu-Sb ternary system is inaccurate, and a corresponding modification is accomplished.The rapid solidification behavior of undercooled Ag42.4Cu21.6Sb36 eutectic alloy is studied by glass fluxing method, in which the maximum undercooling is 114K(0.16Te). It is revealed that primary phases, pseudobinary eutectics and ternary eutectics coexist in the samples of small undercoolings. With the increasing of undercooling, microstructures transform from a mixture of primary phases, pseudobinary eutectics and ternary eutectics into anomalous ternary eutectics. By means of calculating nucleation rates, the competitive nucleation among the three eutectic phases is analyzed.The containerless rapid solidification of Ag42.4Cu21.6Sb36 eutectic alloy is investigated by drop tube. The microstructural morphology transition takes place as droplet diameter decreases. For the droplets of different sizes, the cooling rate is determined by calculations. It is found that undercooling increases with the decreasing of droplet diameter.Ag42.4Cu21.6Sb36 alloy ribbons are obtained by melt spinning method at two wheel speeds. The growth pattern of microstructures and the influence of some experimental parameters are discussed. In addition, the solidification characteristics of Ag42.4Cu21.6Sb36eutectic alloy by glass fluxing, drop tube and melt spinning method are compared to reveal some common kinetics features.