1. The melting point of the flux should be lower than that of pure magnesium and magnesium alloy.
2. The melting point of the flux should be within the range of 953~973 K to meet the melting process requirements of magnesium alloy.
3. The flux should have a large density difference between the melt of magnesium alloy and easy to be eliminated from the melt.
4. The flux of different use should have different surface tension. For example, the protective covering agent, its surface tension should be smaller to increase the effect of wettability on the surface of the melt and cover. It is required to wet the wall of the furnace and the wall of the crucible and to keep it protected. The melting agent of the refining shall have the surface tension of an appropriate size, it can separate the flux from the melt, and it can absorb and dissolve large amounts of non-metallic inclusions from the melt to achieve the purpose of purification.
5. The covering flux should be small enough to close the broken overburden in time. The flux of the refining should have an appropriate degree of gout to increase the ability to transition non-metallic inclusions to the flux and to be easily separated from the melt.
6. In the molten casting temperature, the flux should have thermal stability and chemical stability, not volatilize, not decomposed, and do not react with any group element and furnace lining in the alloy.
7. Pollution-free and low material consumption.
8. Moisture absorbability and moisture should be as small as possible, which are good for metal quality and safety and easy to keep.
9. No inclusion and inclusion elements harmful to the melt.
10. The raw material source is wide, the price is low, it does not increase the production cost of alloy material obviously.