Among the rare metals, many members are "tough". They not only have high melting points but also strong corrosion resistance and are not easily oxidized in the air, so they are called the "tough guys" among metals.
The toughest metal is tungsten. Its melting point is as high as 3,410°C, the highest among all metals, so it can be used as a filament material. Withstanding high temperatures of 2,000°C is a piece of cake for tungsten. Tungsten is mainly used in hard alloys, special steels, and other products, and is widely used in the defense industry, aerospace, and information industry. It is nicknamed "the tooth of industry". The second-ranked melting point belongs to rhenium, which is 3,180°C. It's worth mentioning that rhenium is a truly rare element. Its content in the earth's crust is very rare and scattered, only higher than those of hafnium and radium. Therefore, it is the last element discovered in nature. Since Mendeleev discovered the periodic law of elements, scientists have not found it for more than half a century until it was discovered by German chemists in 1925.
The third-ranked melting point belongs to osmium, which is 3,045°C. At the same time, it is also the heaviest metal in nature, with a density of 22.4 g/cm3. The fourth-ranked is tantalum, with a melting point of 2,996°C. Other metals with melting points exceeding 2,000°C include molybdenum and hafnium. Molybdenum is a trace element necessary for humans and animals. The total amount of molybdenum in an adult human body is 9 mg, with the highest content in the liver and kidneys. Plants can fix nitrogen under the action of molybdenum and convert nitrogen into a form that can be absorbed. Molybdenum is mainly used in the refining of various alloy steels, stainless steels, heat-resistant steels, and superalloys, and is widely used in the military industry, also known as "war metal". The melting point of hafnium is 2,233°C. It's worth mentioning that an alloy of hafnium is the substance with the highest known melting point, about 4,215°C.