The application of rare earth magnesium alloys in China's aerospace field can be traced back to the 1950s. At that time, the skin, frame and engine casing of the imitation aircraft and missiles in China were all made of rare earth magnesium alloys. Since the 1970s, our attack aircraft, helicopters, missiles, satellites, etc. have also begun to promote the application of rare earth magnesium alloys. For example, the important parts of the helicopter engine reduction gearbox, fighter wing ribs and other important parts are the selected ZM6 alloy-cast magnesium alloy One of the three major series "magnesium-rare earth metal-zirconium alloy", that is, a high-strength heat-resistant magnesium alloy with neodymium as the main alloying element.
Magnesium alloy is the lightest metal structural material and is widely used in the manufacture of important mechanical equipment parts on aircrafts, fighters, missiles, spaceships, and satellites to reduce the weight of parts, improve the maneuverability of aircrafts, and reduce the launch cost of spacecrafts. In addition, magnesium alloys are also widely used in rail transportation, automobiles and 3C products. Magnesium alloy is known as "green engineering material for the 21st century" because it has the advantages of high specific strength / specific rigidity, dimensional stability, easy processing, good thermal conductivity, damping and shock absorption, electromagnetic shielding and easy recycling.
However, the application of magnesium alloys in the aerospace field is limited. Because the strength of magnesium alloy is low, especially the high temperature strength and creep resistance are poor. Moreover, magnesium alloy castings are easy to form shrinkage and thermal cracks, the yield is low, and the plastic processing conditions of magnesium alloy deformed parts are difficult to control, resulting in unstable structure and mechanical properties. In response to these problems, after more than 20 years of exploration and development, Chinese researchers have finally made great progress in new materials and processes for magnesium alloys.
For new magnesium alloy materials, based on rare earth elements, which can effectively improve the mechanical properties and heat resistance of magnesium alloys, researchers have developed two new types of rare earth magnesium alloys, namely JDM1 cast magnesium alloy and JDM2 cast magnesium alloy. Among them, JDM1 cast magnesium alloy is a magnesium alloy with low rare earth content, and its typical room temperature mechanical properties are yield strength of 140MPa, tensile strength of 300MPa, and elongation of 10%; JDM2 cast magnesium alloy is a magnesium alloy with high rare earth content Its typical room temperature mechanical properties are yield strength 240MPa, tensile strength 370MPa, and elongation 4%. Compared with the traditional commercial WE54 high-strength heat-resistant magnesium alloy, JDM2 magnesium alloy has better high-temperature and low-temperature mechanical properties.
In terms of new magnesium alloy technology, recently, BGXT has successfully developed large-size rare earth magnesium alloy rods. BGXT Rare Earth Institute Pilot Base has cooperated with Northeastern University and Shanghai Jiaotong University to develop semi-continuous casting technology, which has breakthroughly solved large-size rare earth magnesium alloy rods. Large internal stress, large radial grain size difference, uneven mechanical properties and other technical difficulties, successfully developed a large size rare earth magnesium alloy rod with a diameter of 550mm, marking the low cost of large size, high quality forged wheels and extruded profiles It is possible to become a domestic leader. At the same time, BGXT Rare Earth Institute introduced the QC830 cold chamber die casting system to realize the annual production capacity of 300 tons of rare earth magnesium alloy thin-walled devices, and accelerate the application of rare earth magnesium alloy materials in the downstream field.