The evaluation of cesium diode electrode materials called for braze fillers with very low vapor pressures and a wide range of melting points. Binary alloys of low vapor pressure refractory metals (<10-10 torr at 1500°K and < 10-5 torr at 2000°K) were chosen to fill this need. These alloys of Th, Zr, Hf, Ru, Nb, Ir, Mo, Ta, Os, Re, and W have reported melting point minima or eutectics from 1510°K to above 3000 K.nPreliminary data are compiled on the use of service of these braze alloys. Melting points and surface wetting on a Ta base are given. Re sults of brazing Ir, LaB6, Nb, Re, W, and Zr-22 wt％ ZrO2 materials into Ta and Nb-1％ Zr bases are presented. Current braze usage is summarized.
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