The Preparation Of ZA12Zinc Alloy Slurry By Cooling Slope And Its Reheating Microstructure Evolution

High quality semi-solid slurry preparation is the key to the semi-solid metal process(SSM), and light alloys such as aluminum and magnesium alloy type are the main research topic. In this paper, based on predecessors’research methods, ZA12zinc alloy semi-solid slurry was prepared by cooling slope, which conventionally used in rheo-die casting. Processing parameters in terms of pouring temperature, slope length and slope angle are analyzed systematically to investigate their effect on the microstructures and properties of ZA12semi-solid slurry. A new method for slurry preparation, involving the combination of cooling slope with refining agent has been proposed. Isothermal temperature and isothermal time are analyzed to find how they affect the microstructures of ZA12semi-solid slurry and metal mold casting. The results of the experiments are as follows:Pouring temperature, slope length and slope angle affect grain size and morphology of semi-solid slurry by impacting the heat transfer, shearing force and action time between melt alloy and slope. In present study, slurry produced under condition include pouring temperature460癈, cooling slope length50cm and cooling slope angle30■exhibited smallest and roundness crystal grain. HBW is inversely proportional to the grain size and proportional to its roundness on the material hardness testing. Friction performance test revealed slurry prepared by cooling slope has lower wear loss, better stability and lower friction coefficient with respect to the common metal mold cast specimens. The proposed method which combined cooling slope with refining agent, show a much higher grain refining efficiency.Microstructure evolution of both metal casting and cooling slope ZA12during a semi-solid reheating is investigated. When the isothermal time is lh, for the metal casting ZA12alloy, the best isothermal temperature is395癈-400癈, while for the samples prepared by cooling slope, a lower isothermal temperature of390癈, as well as better spheroidization effect are observed. When the isothermal temperature is390癈, for the metal casting ZA12alloy, the best isothermal time is1.5h-2h, while for the samples prepared by cooling slope, a lower isothermal time of lh, as well as better spheroidization effect are observed.