The Surface Tension of Undercooled Binary Iron and Nickel Alloys and the Effect of Oxygen on the Surface Tension of Fe and Ni

The surface tension of the undercooled binary alloys, iron-nickel and nickelcobalt, was measured as a function of composition and temperature using the oscillating droplet method combined with electromagnetic levitation. The measurements cover a wide temperature range, including the overheated as well as the undercooled regime. In addition, the effect of oxygen on the surface tension of the elements, iron and nickel, has been determined. When exposed to an oxygen/helium gas flow of constant composition and flux, the surface tension decreases exponentially with increasing exposure time. The oxygen coIntent in the gas mixture was monitored by a gas analyzer using a zirconia transducer. In addition, the amount of oxygen in the sample was determined by X-ray photoelectron- spectroscopy (XPS) before the experiment as well as for processed samples.