The Effect of Modification Techniques on Refining of Primary Si Phase in Hypereutectic Al-Si Alloy

The effect of process parameters,including of alterative,modification temperature,modification time,casting temperature,and so on,on refining of primary Si phase in hypereutectic Al-Si alloy were researched.The results indicated that these parameters affect the modification severely.When choosing red phosphor+ aluminium powder + flux as the alterative,the element phosphor can be absorbed easily,and after modification,more primary Si phase exist in the alloy.800℃ is the best modification temperature for A390 alloy,after modificated at that temperature,the primary Si phase distribute uniformly,and the average grain size is 13μm.When modification temperature higher than that,the primary Si grain would grow up,contrarily,when the temperature lower than that,the primary Si grain would congregated.In our research,the best phosphor modification time for the hypereutectic Al-Si alloy is 20-30 minutes and the best casting temperature is 800℃.When the casting temperature lower than 800℃,primary Si grain would congregated,and when the temperature higher than that,the primary Si grain would coarse.