Correlation between phase transformation and surface morphology under severe plastic deformation of theAl87Ni8La5 amorphous alloy

Abstract

The parameters of shear bands and their relationship with the nanocrystallization process in the Al87Ni8La5 amorphous alloy under deformation were studied by X-ray diffraction, high resolution electron microscopy, and atomic force microscopy. Deformation of the samples was carried out by room temperature rolling and high pressure torsion methods. An increase in the deformation level was found to lead to an increase in the surface roughness, an increase in the step height, and the formation of Al nanocrystals. The thickness of the shear band, determined from the width of the minimum steps, does not depend on deformation type and is approximately 15 nm; the height of the minimum steps ranges from a few tenths of nm to 1.5 nm. The formation of nanocrystals occurs when the shear band power corresponding to the true deformation e = 4.42 is reached.