Los alamos national laboratory has developed a new type of irradiation-resistant tungsten alloy, which may solve the problem of weak fracture resistance of materials in the extreme irradiation environment in fusion reactors.
The Key components in fusion reactors, such as filters or plasma materials, need to meet performance requirements, including low activation, high melting point, good mechanical properties, low sputtering corrosion, and low tritium retention/co-deposition. These components must operate at high temperatures for extended periods of time without failure or extensive erosion from exposure to large plasma heat and high energy neutral hydrogen isotopes (D and T). Tungsten is a good choice for plasma materials because of its higher melting temperature, lower corrosion rate and lower tritium retention. However, tungsten itself has a very low fracture toughness, which severely limits the effective operating temperature of components, and at the same time creates a series of manufacturing difficulties.
It has been observed that D and He bubbles at medium temperature (<800K) and He bubbles at high temperature (>1600K ). The mechanism of the formation of these phenomena is not clear, but scientists guess that it is largely due to the accumulation of D and He in the material defects. At slightly lower temperatures ( 1250-1600k ), nanoscale foaming can be observed by exposing tungsten to He plasma. Under the operating conditions close to the international experimental thermonuclear reactor, the surface of the material can be found to have nano-structure morphology. The increased surface area and brittleness of these nanostructured surfaces have raised concerns about tungsten carbide as a plasma material for fusion reactors.
The new tungsten alloy is a kind of nanocrystalline tungsten - tantalum - vanadium - chromium alloy in the form of thin film. "We haven't tested performance in high corrosion conditions," Saez said. But I think it will do well under those conditions. In addition, if it is as ductile as expected, tungsten alloys with high melting points could also be used as turbine materials.
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