Electron-beam zone purification and analysis of tungsten

Mass spectrographic, combustion-chromatographic, inert-gas fusion, and colorimetric techniques of analysis have been applied to the determination of impurities in zone-melted tungsten. The mass spectrograph, in sampling only small quantities of the specimen, revealed that the impurity distribution was in general inhomogeneous. The results indicated that only the most refractory impurities were redistributed by zone-refining action and that the primary mechanism of removal is generally by volatilization.