Tungsten has the highest melting point of any metal, and it can be alloyed with other elements to increase strength. Tungsten is used to make many practical products such as mining equipment, light bulbs, household tools, industrial machinery parts, and military weapons. It is also used to make filaments for sophisticated devices unrelated to lighting such as ion implanters, vacuum gauges and heating elements for semiconductor processing equipment. These types of devices require a very hard, long-lasting material that is easy to use and poses no environmental hazards.
Tungsten is brittle, but it can be made to behave more like a structural metal by lowering the temperature of its brittle-to-ductile transition and increasing its fracture toughness. This is an important step towards making tungsten useful in applications that demand both high strength and low density.
The ductility of tungsten foil is extraordinary; it can be bent plastically at room temperature (RT). This ductility is not explained by a single mechanism, but multiple mechanisms might control it. These include the ultra fine grained microstructure, the high amount of mobile edge dislocations, and the “foil effect”, whereby dislocations that move to the free surface are annihilated (see Figure 1).
Tungsten is hard and crack-sensitive, and handling it requires a level of skill beyond that required for most other metals. It must be cooled to very low temperatures with liquid nitrogen or helium, and it is recommended to use diamond silicon carbide wheels for cutting.