The Study On The Modification And Detection Of Al-Si Alloy

In this paper,relative results of sodium,strontium and sodium-strontium composite modification of aluminum-silicon alloy are analyzed through consistent experiments.The relationship between the amount of sodium salt modifier,the modification effect of alloy and the effective period of modification was studier.By using the thermal analysis instrument developed by ourselves,the cooling and solidification crurves of different metamorphic time was generated,whose eutectic platform temnperature difference was observed,and combined with metallographic structure data,the influence on the microstructure of ZL101 alloy under different amounts of sodium salt was analyzed.It was found that when the amount of sodium salt was 2.0%and the time reached 8 minutes,the super-cooling degree was in its peak,the modification effect was the best,the effective period of modification was about 60 minutes,and the eutectic silicon changed from needle-like to fibrous,the goal of refinement achieved,by which the relationship between sodium salt modifier amount,modification effect of alloy and effective period of modification was well explained.The incubation period,decay period,gas content of strontium metamorphism and the influence on the microstructure of the alloy were studied.The result shows that the incubation period of Sr metamorphism was about 15 minutes,and the metamorphism effect was of its best 60 minutes after the strontium metamorphic modifier was added,and the whole process of metamorphism lasted about 330 minutes.The strontium metamorphic agent increases the inhalation tendency of the alloy liquid,and as the modification effect declines,the gas content returns to the originanlk level.The effect of sodium-strontium composite modifier on the microstructure of ZL101 alloy was studied,the eutectic platform temperature of the pressure-reduced solidified samle at different metamorphic time after adding sodium-strontium composite modifier was analyzed by thermal analysis instrument,the whole metamorphic process of sodium-strontium composite modifier was analyzed.By observing the number and size of pores on the solidified sample,the effect of sodium-strontium composite modifier on the inhalation tendency of ZL101 alloy was analyzed.The result shows that after adding sodium-strontium composite modifier,both the effective time of modification was prolonged and the incubation period was reduced compared with the single metamorphism of sodium and strontium,and the efficiency of metamorphic treatment was improved.And 13 minutes after the sodium-strontium composite modifier was added,the modification effect is the best,the modification period is about 120 minutes.The number of pores on the solidified sample increased dramatically after the composite modifier was added,therefore,we can draw the conclusion that the inhalation tendency of alloy liquid was improved by sodium-strotium composite modifier.