LAUSR

The first time that materials scientist Brian Cantor took a stab at mixing a lot of different elements together was in 1980. Then a lecturer at the University of Sussex, Cantor wondered why metallurgists focused only on tweaking recipes for established metal alloys or refining synthesis processes. “Why is it we’ve never had lots of components together?” he asked. “People kept saying, ‘That is daft.’ ” But he thought it was worth a try. So he went to the cabinet where his lab stored its various metal samples, selected 20 he thought might go together, and persuaded an undergraduate researcher, Alain Vincent, to melt and mix them. This initial attempt didn’t produce a usable alloy. Neither did mixing smaller sets of 16 or 10 metals, though the effort did contribute to Vincent’s bachelor’s thesis. Eventually Cantor, who later moved to Oxford University, and other colleagues repeated the experiments and jump-started a new field when they published the research online in 2003. A separate paper published a few months later by Jien-Wei Yeh, a materials scientist at National Tsing Hua University, gave these materials their name: high-entropy alloys (HEAs). “I would have loved to have discovered [the new alloy] on the basis of really fundamental theory or a really inspired bit of creative experimentation,” says Cantor, now professor emeritus at Oxford. “The truth is it was a random bit of serendipity.” The concept of HEAsalso called multicomponent alloys, multiprincipal component alloys, or compositionally complex alloysis a huge shift in how people make alloys, which have served humanity since the Bronze Age. All traditional alloys consist of one base element with just a small percentage of another element or two mixed in. For example, bronze is mainly copper, with about 12 wt % tin, and maybe a pinch of aluminum or nickel. If you feel like making brass, mix copper and zinc. Steel is iron with a soupco̧n of carbon. But if you limit alloys to one main component, “We’ve used them all up,” says Daniel Miracle, a materials scientist at the US Air Force Research Laboratory. “The last element that was used as an alloy base was titanium in the 1950s and 1960s, and after that we ran out of bases.”