Study of viscosity of $\mathrm{Fe}$–$\mathrm{Cr}$ melts containing $2$ to $40$ at $\%$ of chromium

The temperature, time, and concentration dependences of viscosity $\nu$ of $\mathrm{Fe}$–$\mathrm{Cr}$ melts containing $2$ to $40$ at $\%$ of chromium are studied. It is shown that the observed anomalies in viscosity polytherms in the first heating mode and the hysteresis of $\nu$ in subsequent cooling are due to the slow setting of thermodynamic and chemical equilibrium in the system of crucible–melt–atmosphere, which is shifted to higher temperatures with increasing oxygen content in the alloy. The minimum and maximum of viscosity are observed at $5$ and $12$ at $\%$ of $\mathrm{Cr}$, respectively; they are caused by a concentration change in the binding energy between the atoms, which is determined by the geometric and compositional short-range order. The nonequilibrium state of the melts has no significant effect on the nature of their viscosity isotherms.