Normally, solid metals have a rigid, crystalline atomic structure, but as their name suggests, metallic glasses are more like glass, with a random arrangement of atoms. Composed of complex alloys, they get their unusual structure when molten metal is cooled down extremely quickly, which prevents crystals from forming. The end result is a material that's as pliable as plastic during production but strong as steel afterwards, making them useful for objects like golf clubs and gears for robots.
The Yale researchers developed their new version of the material by taking samples of metallic glass and making nanorods out of it. With a diameter of just 35 nanometers, these rods are so tiny that the atoms have no room for a nucleus. The researchers dub the process "nucleus starvation," and it resulted in a new phase of the material.
"This gives us a handle to control the number of nuclei we provide in the sample," says Judy Cha, lead researcher on the project. "When it doesn't have any nuclei — despite the fact that nature tells us that there should be one — it generates this brand new crystalline phase that we've never seen before. It's a way to create a new material out of the old."