In the alloy composition, the effective elements are aluminum, copper, and magnesium; the harmful elements are lead, cadmium, tin, and iron.
(1) The role of alloying elements
1) Aluminum is the main alloying element in zinc alloys, which can greatly improve the fluidity of zinc liquid, thereby improving its casting properties. The eutectic alloy with 5% aluminum has the best flow, but the impact strength is low. Aluminum in the range of 3.9% to 4.3%, on the one hand, strengthens the alloy, effectively refines the grains, and improves the strength; on the other hand, it can make the alloy have better casting properties. Aluminum has the effect of grain refinement and solid solution strengthening, which can reduce the reaction rate of zinc and iron. When the aluminum content exceeds 4.3%, the alloy becomes brittle and the casting is difficult to process; when the aluminum content is less than 3.9%, the forming of thin-walled parts is difficult, and there is a possibility of cooling crack after casting.

2) The role of magnesium is to reduce intergranular corrosion, refine the structure of zinc alloys, improve the wear resistance of zinc alloys, and increase strength and hardness. Generally controlled within the range of 0.03%~0.08%, more than 0.08% is prone to hot brittleness, hot cracking, and fluidity decline. Copper can improve the strength, hardness, wear resistance and corrosion resistance of alloys. When the copper content exceeds 1.25%, the casting size is unstable and the fluidity of the alloy is reduced.