Surface Tension of Molten Nickel-Tungsten Alloy

Surface tension of molten Ni-(5-10)W (mass fraction, %) alloys was measured in the temperature range of 1773-1873 K with an alumina substrate in an Ar+3%H2 atmosphere using an improved sessile drop method. The surface tension of molten Ni-W alloys decreases with increasing of temperature. On the basis of experimental data, the surface tension of molten Ni-W alloys was also theoretically deduced as functions of concentration and temperature using a model of Butler's equation. The surface segregation in Ni-W system was calculated. The measured results agree well with a model for the surface tension. The surface concentration of tungsten is lower than that in bulk.