The results of experimental measurements, molecular dynamics simulation, and theoretical calculations of the viscosity of a cobalt melt in a temperature range of 1400 − 2000 K at a pressure p = 1.5 bar corresponding to an overcooled melt at temperatures of 1400 − 1768 K and an equilibrium melt with temperatures from the range 1768 − 2000 K are presented. Theoretical expressions for the spectral density of the time-dependent correlation function of the stress tensorS(ω) and kinematic viscosity ν determined from the frequency and thermodynamic parameters of the system are obtained. The temperature dependences of the kinematic viscosity for the cobalt melt are determined experimentally by the torsional oscillation method; numerically, based on molecular simulation data with the EAM potential via subsequent analysis of the time correlation functions of the transverse current in the framework of generalized hydrodynamics; and by the integral Kubo-Green relation;they were also determined theoretically with the Zwanzig-Mori memory functions formalism using a self-consistent approach. Good agreement was found between the results of theoretical calculations for the temperature dependence of the kinematic viscosity of the cobalt melt using experimental data and the molecular dynamics simulation results. From an analysis of the temperature dependence of the viscosity, we obtain an activation energy of E = (5.38 ± 0.02) × 10 −20 J.

The shear viscosity of liquid cobalt at the pressure p = 1.5 bar and at the temperatures corresponding to equilibrium liquid and supercooled liquid states is measured experimentally and evaluated by means of molecular dynamics simulations. Further, the shear viscosity is also calculated within the microscopic theoretical model. Comparison of our experimental, simulation and theoretical results with other available data allows one to examine the issue about the correct temperature dependence of the shear viscosity of liquid cobalt. It is found a strong correlation between the viscosity and the configuration entropy of liquid cobalt over the considered temperature range, which can be taken into account by the Rosenfeld's model.

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