Constrained deformation of an Al based amorphous alloy by cold rolling

In this work, we report on the mechanisms of deformation and fracture of an Al(87)Ni(7)La(6) amorphous alloys by cold rolling. Ribbons were cold rolled at room temperature embedded in pure Al-foils (volume fraction 20%). Scanning Electron Microscopy observations of the cross section of the deformed samples revealed that, after a few rolling passes, ribbons broke into fragments and formed shear bands because of the load exerted by the ductile Al matrix starting from the roughness on the surfaces. The shear band offset was higher near the fracture surface, suggesting that a stress concentration occurs when the slip of shear band is hindered by the presence of constraint. In ribbons rolled alone elongation above 3% was achieved as well as flattening of the surface roughness. Fracture surfaces of ribbon fragments presented mainly features due to brittle shear and a limited number of veins and filaments suggesting mixed mode of fracture. No formation of crystals in the shear bands was evidenced by Transmission Electron Microscopy and Differential Scanning Calorimetry.