Aluminum alloys exhibit different properties due to the addition of different metal elements. Among various metallic elements, had a greater influence on the performance of aluminum alloy elements with copper (Cu), magnesium (Mg), silicon (Si), iron (Fe) and manganese (Mn), nickel (Ni), zinc (zinc), etc., because according to the utility of finished aluminium coil is different in joining in the process of the impurity element due to the lower melting point, Different structures form different compounds with aluminum, and thus have different effects on the properties of aluminum alloys.

Copper (Cu)

advantages

Copper is an important alloying element and has the effect of solution strengthening and aging strengthening. The strengthening effect is best when the copper content is 4% to 6.8%, so the copper content of most duralumin alloys is in this range. Increase the copper content, improve the fluidity of the alloy, tensile strength and hardness, so that the mechanical properties can be improved, machinability becomes better.

Disadvantage

reduce corrosion resistance and molding, increase the hot crack tendency.

Mg

Advantage

The strengthening effect of magnesium on aluminum is significant, and the tensile strength increases by about 34MPa per 1% increase of magnesium. Reinforcement may be supplemented if less than 1% manganese is added. Therefore, manganese can reduce the magnesium content and the tendency of hot cracking. In addition, manganese can also make Mg5Al8 compound average precipitation, improve the corrosion resistance and welding performance.

Disadvantage

Mg2Si will make the casting brittle.

Si

Advantage

In the equilibrium phase diagram of Al-Mg2Si alloy system, the maximum solubility of Mg2Si in aluminum is 1.85%, and the reduction is small with the decrease of temperature. In the deformed aluminum alloy, the addition of silicon to the aluminum plate is only the welding material, and the addition of silicon to aluminum also has a certain strengthening effect. The casting property of the alloy can be improved by adding Si. Silicon and aluminum can form a solid solution, which can improve the alloy’s high temperature modeling, reduce shrinkage, no hot crack tendency. Improves tensile strength, hardness, machinability and strength at high temperature while reducing elongation.

Disadvantage

The crystallized Silicon (Si) tends to have hard points of free silicon, which leads to poor machinability. The crucible of casting is corroded seriously by high silicon aluminum alloy

Fe

Advantage

The adhesion of aluminum alloy to die is very strong, especially when the iron content is less than 0.6%, that is, it is not easy to demoulding. When the fe content exceeds 0.6%, the adhesion phenomenon is greatly reduced.

Disadvantage

When the iron content of aluminum alloy is too high, the iron exists in the alloy in the form of FeAl3, Fe2Al7 and Al-Si-Fe flake or needle structure, forming metal compounds, forming a hard point. This kind of structure will also reduce the mechanical properties, increase the hot cracking, so that the casting brittleness. When the amount of iron (Fe) is over 1.2%, the fluidity of the alloy is reduced, the quality of the casting is damaged, and the life of the metal components in the die casting equipment is shortened.

Mn

Advantage

The alloy strength increases with increasing solubility. The maximum elongation was achieved when the manganese content was 0.8%. Manganese (Mn) can prevent the recrystallization of aluminum alloy, increase the recrystallization temperature, and refine the recrystallized grain significantly. The refinement of recrystallized grain is mainly hindered by the dispersion of MnAl6 compound. Another function of MnAl6 is to dissolve impurity iron (Fe) and form (Fe, Mn) Al6, so that the sheet or needle-like structure formed by iron in aluminum alloy becomes fine crystal structure, reducing the harmful effect of iron.

Disadvantage

Too much manganese can cause segregation. Al-mn alloy long and short aging hardening alloy, that is, can not be heat treatment strengthening.

Ni

Advantage

It has a tendency to increase tensile strength and hardness, which greatly affects corrosion resistance.

Disadvantage

Reduced corrosion resistance and thermal conductivity.

Zn

Advantage


When zinc and magnesium are added to aluminum, the strengthening phase Mg/Zn2 is formed, which has obvious strengthening effect on the alloy.

Disadvantage

When zinc is added to aluminum alone, the improvement of strength of aluminum alloy is very limited under the condition of deformation, and there is also a tendency of stress erosion cracking, so its application is limited.