Locally fluctuating cooling rate as possible reason for non-crystalline plasticity in metallic glasses

The preparation process of a CuZrAl metallic glass is simulated by molecular dynamics. Different temperatures of the initial liquid state and variation of the cooling rate over five decades are considered. Elastic moduli, mass density and frequency of icosahedral clusters follow a power-law scaling with the cooling rate. The ratio of shear to bulk modulus is most sensitive to changes of the cooling rate. Assuming local fluctuations of the cooling rate occurring during the preparation process, regions characterized by comparably low values of shear modulus, mass density and frequency of icosahedral clusters can be proposed as atomistic realizations of flow defects, at which non-crystalline plastic deformation is initiated.