Effect Of Ti And Sc Elements On Fluidity And Anodizing Properties Of Al-Mn Casting Aluminum Alloys

Using cast aluminium alloy instead of wrought aluminium alloy to produce 3C product shell can save a lot of cost and improve production efficiency.Due to the existence of a large number of Si phases in traditional cast aluminium alloys,its surface anodization effect is poor,and it can not meet the appearance requirements of 3C products.The development of an anodizable cast aluminium alloy has great application prospects and market demand.Al-Mn alloys have lower eutectic composition points and have better potential for anodic oxidation than traditional cast Al-Si alloys.Therefore,in this paper,Al-Mn cast aluminium alloy was taken as the research object,and the effects of common modification elements Ti and Sc on the anodic oxidation,fluidity and mechanical properties of the alloy were studied.The results show that Al-Mn alloy has the best fluidity and mechanical properties when the content of Mn is 2 wt.%.The flow length of Al-2Mn alloy reaches 87%of ADC12 alloy and the tensile strength reaches 110 MPa.The hollow diamond-shaped primary Al₆Mn phase in Al-2Mn alloy dissolves preferentially in the process of anodic oxidation,forming corrosion pits and affecting the anodic oxidation performance of the alloy.The addition of appropriate alloying element Ti can change the morphology and distribution of primary Al₆Mn phase,improve the anodic oxidation effect of Al-2Mn alloy and improve the corrosion resistance of the film.With the increase of Ti content,the solidification interval of the alloy increases and the melt flow length decreases significantly.Moreover,when Ti content is higher than 0.2 wt.%,the melt will precipitate Al₃Ti phase preferentially,increase the melt viscosity,and the flow length of the alloy is less than 80%of that of Al-2Mn alloy.The increase of solidification interval and viscosity is the main reason for the decrease of melt fluidity.The mechanical properties of Al-2Mn alloy can not be improved by adding Ti at the same time.Sc can significantly improve the mechanical properties of Al-2Mn alloy.When Sc content is 0.4 wt.%,the maximum tensile strength is nearly 180 MPa.When Sc content is not higher than 0.3 wt.%,the solidification interval remains basically unchanged,and the melt flow length of the alloy is similar to that of Al-2Mn alloy.When Sc content exceeds 0.3 wt.%,the solidification interval increases.The melt flow length decreases.When Sc content is 0.5 wt.%,the flow length of Al-2Mn alloy is the shortest,which is 90%of the flow length of Al-2Mn alloy.When the Sc content is above 0.3 wt.%,the nanoporous structure of the film has larger holes.With the increase of Sc content,corrosion pits and nanopore size and porosity of the alloy film increase gradually.The addition of Ti/Sc can superimpose the modification effect of Ti and the strengthening effect of SC,and improve the anodic oxidation and mechanical properties of the alloy.When the content of Ti and Sc alloy elements is 0.1 wt.%and 0.3 wt.%respectively,the alloy has good fluidity,excellent anodic oxidation performance and good mechanical properties.