Amorphous shear bands in SmCo5

Abstract

Formation of thin amorphous shear bands has been recently shown to enable plastic flow in crystalline SmCo5 in the absence of dislocations. To bring insights into the criteria for when this mechanism can be active, here we analyze energetics and atomic structure of deformation-induced shear bands in SmCo5. We find that the formation energy of amorphous shear bands is significantly lower than cleavage energies on different crystallographic planes. The density of the atoms in the shear bands decreases by less than 2% due to the amorphization, which indicates a very small dilation. Analysis of local ordering shows that the amorphous shear bands are more disordered than a melt-quenched sample and the overall fraction of icosahedra is much lower than usually reported in metallic glasses, such as Cu–Zr. The influence of amorphous shear bands on the evolution of grain orientations is also discussed.