Research On The Harmless Of Impurity Element Iron And Calcium In Aluminium Alloy

Aluminum Alloy contains many kinds of impurities, In particular, it is difficult to determine the composition of scrap aluminum alloy during remelting, which often leads to the Serious excessive of impurity elements in aluminum alloy. The existence of these impurities has a lot of adverse effects on the microstructure and properties of aluminum alloy. How to eliminate the impurity elements in aluminum alloy or reduce the harm of impurity elements is an important research direction of high quality recycled aluminum alloy. Iron and calcium are present as impurities in most Aluminum Alloy grades. Study on how to eliminate the adverse effects of iron and calcium in the alloy is representative. In this paper, the iron and calcium in A356 aluminum alloy are used as the object. According to the results of theoretical calculation and experiments, introducing the method of composite iron removal and phosphide calcium removal. The better effect of removing impurities from aluminum alloy has been achieved.In the study of Fe element in this paper, borax fluxing agent and Al-Mn alloy was used to achieve the purpose of reduce iron content and change the iron phase appearance. Borax iron-removal agent was added in Early experiments, with the increase of borax content iron content decreased. When the iron-removal agent content is 1.1%, the iron removal rate is 30.6%. After that, with the increase of iron-removal agent, the content of Fe remained unchanged. The mechanical property of the alloy was improved after the removal of iron. From the three aspects of composition, structure and performance, it is found that the residual β-Fe is transformed into Chinese character or block a-Fe, and further improve the alloy properties. In this paper, the optimal solution of Manganese and boron iron-removal is 1.1% Borax and 1.2 ferromanganese ratio. The content of iron here is the content before adding agent.In the study of Ca element in this paper, On the basis of previous studies, the reaction of calcium-removal in Al-Ca-P ternary system is assumed to be:6Na3P04(s)+9Ca(1)+10A1(1)= 5Al2O3(s)+3Ca3P2(s)+9Na2O(s)Gibbs free energy of the reaction is ΔG1033K=-2873462.56J/mol< 0, the reaction can be carried out spontaneously. The results showed that the calcium content in the alloy was decreased with the addition of sodium phosphate calcium-removal agent. The highest calcium removal rate was 80.2% when the amount of calcium-removal agent was added to 2.5wt.%. The structure also changed from coarse branch crystals to columnar crystal.Calcium content decreased, while the tensile strength of the alloy is improved.