... -arc melt, or both, R05400, unalloyed tantalum, powder-metallurgy consolidation, R05255, tantalum alloy, 90 % tantalum 10 % tungsten, electron-beam furnace or ... vacuum-arc melt, or both, R05252, tantalum alloy, 97.5 % tantalum 2.5 % tungsten, electron-beam furnace or ... vacuum-arc melt, or both, R05240 tantalum alloy, 60 % tantalum 40 % columbium, electron-beam furnace or vacuum-arc ...