PHASE STUDIES OF TUNGSTEN-MOLYBDENUM-RHENIUM ALLOYS

S>The constitution diagram was plotted of tungsten and molybdenum solid solutions with up to 50 wt.% ( approximately -40 to 45 at.%) rhenium. The alloys with cross sections parallel to W - Mo, with content of 10, 20, 30, 40, and 50% rhenium, were analyzed, and three isothermal cross sections of cast alloys, annealed at 1750 deg C for 3 hr and at 1000 deg C for 450 br were plotted. The solubility of the solid solution at lOOO deg C extends from the binary tungsten alloy with 32 wt.% rhenium to 46 wt.% rhenium (30.5 at.%). The syatem forms the sigma phase; the binary alpha + sigma phase is found between the sigma phase and the ternary solid solution. The microstructure of alloys with 40 wt.% rhenium is shown. The alloy with 40 wt.% tungaten, 20 wt.% molybdenum is a single phase ternary solid solution at the threshold of solubility, which transforms to binary two-phase alpha + sigma at lowered temperature. The ternary solid solutions of W-Mo--Re have excellent mechanical properties, strength, plasticity, and a high melting point. (R.V.J.)