Superelongation and Atomic Chain Formation in Nanosized Metallic Glass

Bulk metallic glasses are brittle and fail with no plastic strain at room temperature once shear bands propagate. How do metallic glasses deform when the size is less than that of shear bands? Here we show that Al(90)Fe(5)Ce(5) metallic glass with a size <20 nm can be extremely elongated to similar to 200%. Remarkably, even an atomic chain was formed after sample necking, which was never observed in metallic glasses. The unexpected ductility may originate from the fast surface diffusion and the absence of shear band formation, and may guide the development of ductile metallic glasses for engineering applications.