FURTHER STUDIES ON RHENIUM ALLOYING EFFECTS IN MOLYBDENUM, TUNGSTEN AND CHROMIUM

摘要

Further studies on molybdenum-rhenium alloys indicate that the improved fabricability is associated with redistribution of the grain-boundary oxide as a complex rhenium-molybdate. The tolerance for oxygen in Mo-35Re is several hundred ppm, but small increases in carbon or nitrogen render the alloy less fabricable. The contribution of valence electrons from rhenium to the molybdenum lattice is believed to be associated with the reduced interstitial solubility. The improved ductilities of Mo-35Re and W-30Re are associated with lower interstitial content, enhanced capacity for slip at low temperatures, and associated with low critical stresses for deformation by twinning, which appears to be a function of rhenium content alone. Rhenium also significantly lowers the ductile-to-brittle transition temperature of chromium to below —196 C in bending.