The Study On The Modification Of Al-Si Alloy

Al-Si alloy because of its good casting properties and mechanical properties are widely used.In order to improve the material mechanical properties modifications are widely used in industry.The Sr addition to Al-Si alloy has good metamorphism,and has no pollution,but keep good remelting,keep long time,so Sr metamorphic is widely used at home and abroad.Thermal analysis method can detect the melt quality after modification treatment quickly and accurately,the effective criterion of the eutectic silicon metamorphism is the temperature of the eutectic silicon before and after modification.We often add other alloying elements to Al-Si alloy for improving the comprehensive performance of Al-Si alloy,the influence of alloying elements on alloy solidification process is related to metamorphic thermal analysis test directly.Using the thermal analyzer which was created independently analysing the influence of various alloying elements in alloy solidification process.Design experiments with orthogonal experiment method,to get the characteristic parameters on thermal analysis for analysis,according to the extreme value of each element of qualitative draw the influence trend diagram,analysing from the overall trend.Si which is the main factor,has the greatest effect among the elements of alloy in solidification process.The eutectic solidification temperature of multielement alloy increases with the increase of Si.Cu and Mg element has a little influence on eutectic platform,Mn and Ti have negligible impact on eutectic platform.This article has carried on the comprehensive study of Sr metamorphic technology,studying the changes of Al-Si alloy with different Sr addition,including the thermal analysis curves and the microstructure of alloy.Adding the same Sr to the alloy of different Si content has different effects on their microstructure.Found containing 7% Si alloy with 0.05% Sr metamorphic completely,needle-like eutectic silicon into smallgranule,eutectic growth temperature decrease.Inclusive of 9% Si alloy added Sr 0.03%can achieve a good effect,but when added more Sr to alloy cannot get a good effect during metamorphism.Containing 12% Si alloy with Sr addition amount increasing in metamorphic the effect that they achieve is getting better and better.For containing7%-12% Si hypoeutectic and eutectic aluminum-silicon alloy when add same Sr in alloy,getting greater effect that eutectic silicon transforming more and more obvious which has higher content of Si.Different content of Si in aluminum-silicon alloy when Sr modification treatment,the best addition of Sr is not same.