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(1) The strength and hardness of pure magnesium polycrystals are not high, so pure magnesium cannot be directly used as a structural material, and pure magnesium is usually used to make magnesium alloys and other alloys.

(2) Magnesium alloy is the most developed and applied potential green engineering material in the 21st century

Performance comparison between magnesium alloy and other alloy materials

Magnesium in aluminum, copper, zinc, zirconium, hafnium and other metals can form an alloy, which is an alloy with pure magnesium, its mechanical properties are better, is a good structural material. Although wrought magnesium alloy has good comprehensive performance, magnesium is a close-packed hexagonal lattice, which is difficult to plastically process and has high processing cost. Therefore, the amount of wrought magnesium alloy is much smaller than that of cast magnesium alloy. There are dozens of elements in the periodic table that form alloys with magnesium. Magnesium and iron, barium, potassium, sodium, etc. cannot form an alloy. Among the applied magnesium alloy strengthening elements, alloying elements can be classified into three categories according to the influence of alloying elements on the mechanical properties of binary magnesium alloys:

1. The elements that increase the strength are: Al, Zn, Ag, Ce, Ga, Ni, Cu, Th.

2. The elements that improve toughness are: Th, Ga, Zn, Ag, Ce, Ca, Al, Ni, Cu.

3. Elements that enhance toughness and have little change in strength: Cd, Ti, Li.

4. Elements that significantly increase strength and reduce toughness: Sn, Pd, Bi, Sb.

Effect of impurity elements in magnesium

A. Most of the impurities contained in magnesium have an adverse effect on the mechanical properties of magnesium.

B, MgO more than 0.1% will reduce the mechanical properties of magnesium.

When the content of C and Na exceeds 0.01% or the content of K exceeds 0.03, the tensile strength and other mechanical properties of magnesium are greatly reduced.

D, but at the same time containing Na up to 0.07% and containing K up to 0.01%, the strength of magnesium does not decrease, but only reduces its plasticity.

High-purity magnesium alloy has corrosion resistance comparable to that of aluminum

1. The magnesium alloy matrix is a close-packed hexagonal lattice. The magnesium is relatively active and the oxide film is loose. Therefore, the casting, plastic deformation and anti-corrosion processes are more complicated than the aluminum alloy.

2. The corrosion resistance of high-purity magnesium alloys is comparable to or even lower than that of aluminum alloys. Therefore, the industrial production of high-purity magnesium alloys is an urgent problem to be solved in the large-scale application of magnesium alloys.