Increased ductility of Ni-based metallic glass ribbon pre-annealed at [beta]-relaxation temperature

The lack of ductility is known to be a major drawback in the mechanical properties of amorphous alloys. A temperature impact is often used, as a factor to improve the mechanical parameters of these thermally unstable materials. A thick Ni.sub.82.1Cr.sub.7.8Si.sub.4.6Fe.sub.3.1Mn.sub.0.2Al.sub.0.1Cu.sub.0.1B.sub.2 metallic glass ribbon was subjected to a series of one-hour anneals between 50 and 700 °C. Annealing at 250 °C revealed an increase in the density of the ribbon accompanied by structure rearrangement responsible for the [beta]-relaxation process. In addition, the metallic glass demonstrated high ductility along with high tensile strength and hardness under load. Based on the analysis of transformation of excess free volume in the vicinity of the [beta]-relaxation temperature, a mechanism explaining the attainment of ductility maximum realized in metallic glass under loading has been proposed.