A simple alloy has claimed the crown for toughest material ever recorded. In a new study, a team led by researchers at Berkeley Lab ran the alloy through a series of tests and discovered not only its incredible toughness, but high strength and ductility that actually improve in colder temperatures, unlike most known materials.

The alloy in question contains chromium, cobalt and nickel (CrCoNi), and it belongs to a class of metals called high entropy alloys (HEAs). Most alloys are made up of one dominant element with smaller amounts of others added in, but HEAs contain equal amounts of each element. This can give them some impressive properties, such as high strength-to-weight ratios, an elastic modulus that rises with the temperature, or ultra strength and ductility.

In previous work, the researchers found that CrCoNi showed high strength and toughness at low temperatures of around −196 °C (−321 °F). For the new study, the team investigated how it would hold up at even colder temperatures of −253 °C (−424 °F), at which helium exists as a liquid. And sure enough, its toughness hit new heights in preventing cracks propagating.

A textbook theory for the freezing of water also explains the growth of a new phase in a more complicated phase transition of a different material.

When water freezes, the ice forms first in “nuclei”—tiny seed crystals that can grow or shrink and survive only if they reach a minimum size—at least according to the textbook theory. Researchers have now shown that this understanding also applies to a more complicated phase transition in vanadium dioxide (VO₂), a material whose electrical properties and crystal structure both change at its so-called metal-to-insulator phase transition [1]. The team measured the threshold size for the “seeds” that drive this transition and demonstrated a new technique for studying crystal structure transitions. The result suggests that the classical nucleation theory is valid for a range of materials that are important in areas such as catalysis, lasers, and alloy and ceramic manufacturing.

Place a bucket of purified water in a subfreezing-temperature environment, and tiny ice seeds will start forming. Many will quickly dissolve, but those that are larger than a certain threshold size will grow and eventually merge to make a single block of ice. This view of crystallization, associated with classical nucleation theory, has been well accepted for the water–ice transition. Junqiao Wu of the University of California, Berkeley, and his colleagues wanted to test whether the same nucleation phenomenon is at play in VO₂ when it makes a transition from one crystalline structure to another.

It was a simple idea—maybe even too simple to work.

Research scientist James Ponder and a team of Georgia Tech chemists and engineers thought they could design a transparent polymer film that would conduct electricity as effectively as other commonly used materials, while also being flexible and easy to use at an industrial scale.

They’d do it by simply removing the nonconductive material from their conductive element. Sounds logical, right?