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The Knudsen-cell mass spectrometry and the integral Knudsen effusion technique under ultra-high neutral vacuum were used to study evaporation of pure Fe, Cu and molten Fe-Cu alloys containing up to 10.1 mol% Cu in the temperature range of 1 440 to 1 916 K. Standard sublimation enthalpies of Fe and Cu and thermodynamic characteristics of the Fe-Cu liquid solution were calculated. The obtained results and literature data were applied for assessment of potentialities of steel decopperizing technology based on evaporation. The time required for a decrease in Cu concentration from 0.6 to 0.3 wt% through evaporation from the exposed surface of a 160-tons ladle into vacuum of 100 Pa amounts to 5 h. Decopperizing can be accelerated by combination of vacuum treatment with blowing neutral gases through the molten metal. Two processes are responsible for removal of copper in this case: transfer into gas bubbles, free-rising from the ladle bottom to its surface, and evaporation from molten metal surface, turbulized by blowing-through gas. The length of treatment required for the above decrease in copper concentration under the most favorable conditions (the highest vacuum over the ladle and the highest velocity of gas-stream blowing through the molten metal used in metallurgy) reduces to 1.5 h.

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Knudsen effusion mass spectrometry and a static method were used to study the vapor composition and the thermodynamic properties of the Si-P melt with the phosphorous content from 0.09 to 26.5 at.% in the temperature range 1507 to 1831 K. A representative file of experimental data comprising about 100 values of phosphorus activity at various concentrations and/or temperatures was obtained. The thermodynamic characteristics as functions of temperature and concentration were approximated by the ideal associated-solution model under the assumption that SiP and Si 2 P complexes exist in the melt. The boundaries of the region of liquid phase stability on the phase diagram were computed, and agreement with the available experimental information was obtained.The Knudsen effusion experiments were carried out in