SUPERSATURATION AND OPTICAL-PROPERTIES OF METAL-RICH ZR-O AND ZR-N LIQUIDS

The effects of oxygen and nitrogen additions on the optical properties of pure liquid zirconium were investigated under containerless condit ions using rotating analyzer ellipsometry. Liquid zirconium was electr omagnetically levitated and melted, and metered flows of oxygen and ni trogen were added to the melt in separate experiments. The optical con stants (n and k) and the normal spectral emissivity (epsilon(lambda)) of the liquid at lambda = 633 nm were measured over the duration of th e experiments. The measured values of n and k decreased and epsilon(la mbda) increased with the O and N concentrations for the single-phase l iquids. Metastable Zr-O solutions with 135% of the liquidus O-atom con centration were achieved at a temperature of 2260 K. Precipitation of a solid phase from the Zr-N liquid at 2290 K occurred at a concentrati on of 7.6 at.% N. Based on these results, a new method using in situ e llipsometric measurements is described for the accurate determination of liquidus concentrations and temperatures. Dissolved oxygen and nitr ogen were found to influence the optical properties of liquid zirconiu m in a manner proportional to their respective valences.