ã€China Aluminum Industry Network】 1. Alloying Elements Affecting Copper Aluminium-copper alloy rich aluminum part 548, the greater solubility of copper in aluminum is 5.65%, when the temperature drops to 302, the solubility of copper is 0.45%. Copper is an important alloying element and has a certain solid-solution strengthening effect. In addition, CuAl2 precipitated during ageing has a significant aging strengthening effect. The content of copper in aluminum alloys is usually between 2.5% and 5%, and the copper content is between 4% and 6.8%. Therefore, the copper content of most hard aluminum alloys is within this range. Aluminum-copper alloys may contain less silicon, magnesium, manganese, chromium, zinc, iron, and other elements. The silicon-rich Al-Si alloy-rich aluminum part at the eutectic temperature of 577, the greater the solubility of silicon in the solid solution is 1.65%. Although the solubility decreases with decreasing temperature, such alloys are generally not heat-treatable. Al-Si alloys have excellent casting properties and corrosion resistance. If magnesium and silicon are simultaneously added to aluminum to form an aluminum-magnesium silicon alloy, the strengthening phase is MgSi. The mass ratio of magnesium to silicon is 1.73:1. When the Al-Mg-Si-based alloy composition is designed, the content of magnesium and silicon is configured on the substrate in this ratio. In some Al-Mg-Si alloys, in order to increase the strength, an appropriate amount of copper is added, and an appropriate amount of chromium is added at the same time to offset the adverse effect of copper corrosion resistance. The equilibrium phase diagram of the Al-Mg2Si alloy system has a relatively large solubility of 1.85% in the Al-rich Mg2Si and decreases with decreasing temperature. In the deformed aluminum alloy, silicon alone is added to the aluminum and is limited to the welding material. The addition of silicon to the aluminum also has a certain strengthening effect. Magnesium Al-Mg alloy phase equilibrium phase diagram Al rich part Although the solubility curve shows that the solubility of magnesium in aluminum is greatly reduced as the temperature decreases, but in most industrial deformed aluminum alloys, the magnesium content is less than 6 %, and the silicon content is also low, such alloys are not heat-treatable, but have good weldability, good corrosion resistance, and moderate strength. The enhancement of magnesium by aluminum is obvious. With every 1% increase in magnesium, the tensile strength increases by about 34MPa. If you add 1% or less of manganese, you may supplement the strengthening effect. Therefore, after adding manganese, the content of magnesium can be reduced, and the hot cracking tendency can be reduced. In addition, manganese can evenly precipitate the Mg5Al8 compound and improve the corrosion resistance and welding performance. Partial equilibrium phase diagram of the manganese elemental Al-Mn alloy part at the eutectic temperature of 658, the greater the solubility of manganese in the solid solution is 1.82%. The alloy strength increases with the increase of solubility, and when the manganese content is 0.8%, the elongation reaches a large value. The Al-Mn alloy is a non-aging hardening alloy, ie, it is not heat-treatable. Manganese can prevent the recrystallization process of the aluminum alloy, increase the recrystallization temperature, and can significantly refine the recrystallized grains. The refinement of the recrystallized grains is mainly hindered by the growth of the recrystallized grains through the disperse particles of the MnAl6 compound. Another role of MnAl6 is to dissolve the impurity iron and form (Fe, Mn)Al6, reducing the harmful effects of iron. Manganese is an important element of aluminum alloys and can be added separately to form Al-Mn binary alloys, and more is added together with other alloying elements. Therefore, most aluminum alloys contain manganese. Zinc Al-Zn alloy phase equilibrium phase diagram When aluminum rich part 275, the solubility of zinc in aluminum is 31.6%, and at 125, its solubility drops to 5.6%. Zinc alone added to aluminum, under the deformation conditions of the aluminum alloy strength is very limited, there is stress corrosion cracking, tend to limit its application. When zinc and magnesium are added simultaneously in the aluminum, a strengthening phase Mg/Zn2 is formed, which has a significant strengthening effect on the alloy. When the content of Mg/Zn2 is increased from 0.5% to 12%, the tensile strength and yield strength can be significantly increased. Magnesium content exceeds the superhard aluminum alloy required for Mg/Zn2 phase formation. When the ratio of zinc and magnesium is controlled to about 2.7, the stress corrosion cracking resistance is large. If Al-Zn-Mg is added on the basis of copper to form an Al-Zn-Mg-Cu alloy, the base strengthening effect is larger in all aluminum alloys, and it is also an important aluminum alloy material in the aerospace, aviation and power industries. .