Investigation on Electron Beam Melting of Refractory and Reactive Metals

Refractory and reactive metals such as W, Ta, Mo, Nb and Ti were melted by a 300kW Electron Beam (EB) Melting Furnace and the evaporation behavior of metallic and gaseous impurities was investigated. It was found that, when the vapor pressure of a metallic element, poi, was higher than 104Pa at the temperature 100°C over the melting point of mother metal, the content of the element could be decreased to less than 1ppm. The decrease of oxygen content was also observed except for the melting of Ti. However, the other metallic elements with low vapor pressure and gaseous species such as C and N were less removable, in spite of the melting under the condition of ultra high temperature and ultra low pressure.