The function of impurity elements in aluminum alloy(1)

vanadium

Val11 refractory compound is formed in aluminum alloy, which plays a role in refining grains in the process of melting and casting, but it has less effect than titanium and zirconium. Vanadium can also refine the recrystallization structure and increase the recrystallization temperature.

calcium

The solid solubility in aluminum alloy is very low, forming caal4 compound with aluminum. Calcium is the superplastic element of aluminum alloy. Aluminum alloy with about 5% calcium and 5% manganese has superplasticity. Calcium and silicon form CASI, which is insoluble in aluminum. Because the solid solution of silicon is reduced, the conductivity of industrial pure aluminum can be slightly improved. Calcium can improve the cutting performance of aluminum alloy. Casi2 can not strengthen the heat treatment of aluminum alloy. Trace calcium is helpful to remove hydrogen from molten aluminum.

Lead, tin and bismuth

They are low melting point metals. Their solid solubility in aluminum is small, which slightly reduces the alloy strength, but can improve the cutting performance. Bismuth expands during solidification, which is beneficial to feeding. Adding bismuth to high magnesium alloy can prevent sodium embrittlement.