Papers by Keyword: Cu-Ca Alloy

Abstract: Rotating tube method for preparing Cu-Ca alloy semi-solid slurry was investigated. Compared the microstructure of slurry prepared through the tube and of untreated original sample, discussed evolution characteristics of microstructure flowing through the rotation tube, and analyzed effect of process parameter on microstructure. The results show that the semi-solid slurry of Cu-Ca alloy could be prepared through rotating tube process; the melt were hardly affected in the initial stage. The tube began to play a major part in the next stage and the melt were stirred effectively in the last stage; Spherical microstructures of Cu-Ca alloy slurry were obtained through controlling or adjusting the process parameters to control solidification conditions.

Abstract: Cu-Ca alloys and the squirrel cage rotors for induction motors of small capacities were used for the development of thixoforming processes. Processing conditions, motor efficiency and forming defects in macro- and microscale for thixoforming of Cu-Ca rotors have been performed to investigate the microstructural features and the filling phenomena in slots of squirrel cage rotor. Inadequate filling due to the complexity of slot structure, separation of solidified metal from the slot, porosities and phase inhomogenitites were typical microstructural defects found in thixoformed Cu-Ca rotors. Exact flow control in terms of billet and die temperatures at slot gate especially, was necessary to prevent significant defects such as incomplete filling of slot.

Abstract: The microstructures and electrical conductivity of newly developed Cu-Ca alloys for semi-solid forming have been investigated. High purity calcium was added to molten copper up to 1.4% by weight and mold-cast into a rod. Thermomechanical treatment (TMT) has been carried out to evaluate the variation in electrical conductivity and microstructures of Cu-Ca alloys. The electrical conductivity of copper was reduced linearly with the concentration of calcium by , where k is a constant having the values ranging from 16.7 to 20, depending on the processing condition. The introduction of prestrain significantly reduced the grain size during subsequent heating by recrystallization, influencing the electrical conductivity of Cu-Ca alloys.