Thermophysical property data on molten Ni-based superalloys are almost non-existent. Hence, in this study, the viscosities of these superalloys were measured by the oscillating crucible method. The viscosities decreased with increasing temperature. When the logarithm of the viscosity was plotted against the inverse temperature (Arrhenius-type plot), all alloys showed good Arrhenius-type linearity over the temperature range investigated. These results agreed well with those of general pure metals and alloys from previous studies. Thus, the Arrhenius plot can approximate the viscosities of molten Ni-based superalloys. Moreover, the viscosities of the superalloys decreased with increasing Co content. In addition, the B value obtained in this study agreed well with that obtained by the viscosity relationship η = A∙exp(B/RT) and that for the liquidus temperature suggested by Hirai. Thus, the B value has a close relationship with the liquidus temperature.
