Mechanism of shear banding during cold rolling of a bulk metallic glass

摘要

Shear band formation within the roll bite is investigated for the cold-rolled Zr52.5Ti5Cu18Ni14.5Al10bulk metallic glass. The results indicate that shear bands originate on the surface of the specimen in contact with the rolls and propagate approximately at 45° towards the opposite surface. This is accompanied by the rotation of the shear offsets that depends on their position along the arc of contact. The rotation is the medium that transmits the increasing pressure exerted by the rotating rolls to a propagating shear band, while the specimen progressively enters in the roll bite. This mechanism implies that the strain at opposite sides of a band changes sign from compressive to tensile, as indeed experimentally observed by strain analysis across an individual shear band.