Some metals are called rare metals mainly because there are few stocks of these metals in the world. The performance and utilization value of rare metals are often very high, and many rare metals can be processed and used in many fields such as aviation and military applications. Many countries have a serious shortage of rare metals due to many factors such as geographical location or land area. In China, there are many kinds of rare metals with large quantity. The lack of rare metals in many countries is like the lack of brass in our country. Since high performance of rare metals, it can be widely applied. For example, our country is rich in rare earths and tungsten, tungsten has super hardness, and high temperature resistance, in more than 6000 degrees Celsius to melt it. We did not realize the importance of tungsten in the military until very early, when many light bulbs used tungsten filaments. Most of these rare metals are used in anti-armor missiles, like the warheads of some armor-piercing bullets are made of tungsten, and many aircraft in the aviation field have a large amount of rare metals on the surface. Even the engines of warplanes need rare metals. Many countries cannot develop their military industry well due to the limitation of rare metals.