Nb-W-C-O系固溶体の熱力学的性質および減圧炭素熱還元-電子ビーム溶解法によるNb-W合金の製造

抄録

Possibilities and conditions for preparing homogeneous Nb-W alloys by the carbothermic reduction-electron beam melting combination method have been examined with regard to the following items: (1) Determination of the relationship among the CO-pressure, the temperature and the concentration of carbon and oxygen in the Nb-W-C-O solid solutions by the low-pressure gas equilibrium method at 2173 K. (2) Simultaneous reduction of the Nb-W alloys from mixtures of constituent metal oxides, Nb₂O₅ and WO₃, by carbon in vacuum at about 2200 K. (3) Elimination of carbon and oxygen in the carbon-reduced Nb-W alloys by the electron beam melting.
In this process alloying would proceed and be completed at the first reduction stage. Subsequent melting in an electron-beam furnace lowers the carbon and oxygen contents to a commercial grade and consolidates the alloys into ingot. The evaporation deoxidation as in volatile oxides of niobium and tungsten plays an important role in this process.
The purity and homogeneity of the alloys thus prepared have been assured to be a sufficient degree.