High-entropy alloys could make nuclear reactors last longer

New Scientist : One of the major causes of decay in nuclear reactors is the high number of neutrons produced. Neutrons interact with steel in the containment system and make the metal brittle by knocking atomic nuclei out of place. High-entropy alloys are so named because the distribution of the elements in the alloy is random, compared with the more regular arrangement of atoms in steel. These materials are only now being produced with high enough quality for use in research. Kai Nordlund of the University of Helsinki, Finland, and his colleagues have now shown that two high-entropy alloys are much more resistant to neutron radiation than steel. The researchers made extremely thin disks of a nickel-iron alloy and a nickel-cobalt-chromium alloy and then fired a beam of gold and nickel atoms at the disks to simulate the reactor environment. Compared with a pure nickel disk (used in place of steel because calculations are simpler), the alloys experienced two to three times fewer defects. However, it will likely be years before any such material is fully proven as a replacement for steel in nuclear reactors.