1) Magnesium is a flammable metal. This misunderstanding is due to the fact that many pyrotechnic products use magnesium powder to create this impression. In fact, magnesium ingots, magnesium die castings and magnesium profiles will not burn until the temperature rises to the melting point (651°C). Flammable materials include magnesium powder, magnesium wire, and magnesium foil.
(2) Magnesium is a corrodible metal. Through theoretical and experimental studies, it is found that impurity elements such as iron, nickel, copper and the ratio of iron to manganese have a great influence on the corrosion resistance of magnesium alloys. Therefore, the United States has developed a high-purity die-casting magnesium alloy AZ91D. Compared with the original AZ91 A, AZ91 B, and AZ91C, the corrosion resistance of AZ91 D has been improved by more than 100 times. In terms of salt spray corrosion resistance, most die-cast magnesium alloys have surpassed A380 aluminum alloys. In fact, magnesium is similar to aluminum in many ways. Before the surface is sprayed, both are pre-treated to ensure their affinity. Surface pretreatment is usually chemical treatment, which also improves corrosion resistance.
(3) Magnesium is a scarce metal. This view is obviously wrong. In fact, magnesium makes up 2.5% of the mass of the Earth’s crust, second only to aluminum, iron, calcium and potassium. In seawater, the content of magnesium is second only to chlorine and sodium. It can be said that magnesium is inexhaustible.
(4) Magnesium is a difficult-to-form metal. People who have this kind of misunderstanding think that the crystal structure of magnesium alloy is hexagonal close-packed at room temperature, and there is only one movable slip system in the crystal, so they think that magnesium alloy is difficult to form. In fact, this is a one-sided understanding. In fact, magnesium alloys have good plasticity under high temperature compressive stress, and magnesium alloys can be formed by extrusion, forging and rolling. In addition, plastic deformation is only one form of magnesium alloy, which can also be formed by casting, and the die casting performance of this alloy is better than most aluminum alloys.
(5) Magnesium is an expensive metal. An important factor restricting the application of magnesium alloys in the past is that magnesium alloys are more expensive than aluminum alloys. But at present, the market price of magnesium alloy at home and abroad is equivalent to that of aluminum alloy. It is worth pointing out that considering the price can not only be compared by weight, but also consider the impact of their density differences and the characteristics of magnesium alloys in processing and manufacturing on their costs. Overall, magnesium cannot be considered an expensive metal.