Defects and Plastic-Deformation Modes of Bulk-Metallic Glasses

Abstract

Results of the investigation of the point-defect manifestation in the recovery kinetics of Zr41Ti14Cu12.5Ni10Be22.5 and Zr52.5Ti5Cu17.9Ni14.6Al10 bulk-metallic glasses (BMGs) irradiated with 2.5 MeV electrons at 80 K (–193.15 °C) are presented. An observation of the pronounced annealing stages at 155 K and 130 K (–118.15 °C and –143.15 °C), and 225 K (–48.15 °C), shows that irradiation generates stable point defects in BMGs. The ultrasonic vibrations (USVs) of different amplitudes were used to investigate their effects on the cluster boundaries. The Kaiser effect is chosen as a tool for examining the boundary-slip initiation and impact of vibrations on the intercluster-boundary structure. Both the acoustic-emission activity and strength decrease due to the specimen pretreatment by USV. This effect is interpreted as a result of boundary softening under the USV. The inherent tensile strength of a Zr41Ti14Cu12.5Ni10Be22.5 BMG (in atomic percent) in the as-cast state was determined by means of high-field mechanical loading using the field-ion microscopy. It was revealed that the strength is characterized by a strong size effect in a nanometer-scale range as a result of the manifestation of the structural nanoheterogeneities and, in part, the existence of the cluster boundaries.