A metallic glass that is not only very strong but is also as tough as steel is reported this week in Nature Materials. The combined strength and toughness of this metallic glass exceeds that of any other material.

Metallic glasses are made of metallic elements, but in contrast to normal metals their atomic structure is not crystalline, and is much like that of window glass. Metallic glasses are known to be exceptionally strong and can bear high loads until they fail. But once they start to fail they are not very tough and cracks propagate quickly through the material. Marios Demetriou and colleagues adjusted the composition of a metallic glass based on palladium and other elements to arrive at a material that is not only strong but also exceptionally tough ― that is, it deforms rather than breaks under stress ― and is therefore able to stop cracks spreading.