Magnesium is one of the most abundant elements in the earth, accounting for about 2.3% of the surface metal deposits in the crust, next only to aluminum, iron, calcium and potassium. In addition, the content of magnesium in salt lakes and sea water is also considerable. For example, the content of magnesium in sea water is up to 2.1 million tons, accounting for about 0.13%, second only to chlorine and sodium.
The density of pure magnesium is 1.74 g / cm3, about 2 / 3 of that of aluminum alloy, 1 / 3 of that of Zn alloy, 1 / 4 of that of steel and 2 / 5 of that of titanium alloy, which is equivalent to most engineering plastics. The application of magnesium alloy can bring huge weight loss benefits and significant performance improvement. At present, the countries with the most application of magnesium alloy mainly include China, Russia, Israel, the United States, Brazil, Ukraine, Kazakhstan, Malaysia, South Korea, Serbia, etc. China’s Magnesite accounts for 22.5% of the world. During the Tenth Five Year Plan period, China started the development and industrialization of magnesium alloy materials in the key research plan and 863 plan, which effectively promoted the application of magnesium alloy in China. As shown in the figure, China’s magnesium supply accounts for 79%, and has become the largest magnesium supplier in the world.
Magnesium alloy has many advantages, such as high specific strength and stiffness, high damping, electromagnetic shielding, good dimensional stability, thermal conductivity, excellent casting, cutting performance and easy recycling. It is widely used in aerospace, electronic communication, automobile, national defense and military fields. Magnesium alloys can be divided into mg Al, mg Zn, Mg Mn and Mg RE series according to their composition. The rare earth elements have good solution strengthening and precipitation strengthening effects on magnesium alloy. The addition of rare earth elements can improve the room temperature and high temperature strength, high temperature creep resistance, casting performance and corrosion resistance of Mg RE alloy, which makes mg RE alloy have higher high temperature strength, high temperature creep resistance and high temperature corrosion resistance
Excellent creep resistance, good heat resistance and corrosion resistance. At present, y, Nd and Gd are the main elements in mg Re alloys. The content of rare earth elements in mg nd alloys is generally 2.5% ~ 3%, while the content of rare earth elements in Mg-Y and Mg GD alloys is generally more than 6%. Therefore, compared with Mg-Y and Mg GD alloys, Mg nd alloys have lower cost and are widely used in aerospace and automotive fields. At the same time, Mg nd alloys have good biocompatibility and can be used as biomedical materials.