Natural rhenium is a mixture of two stable isotopes. Twenty six other unstable isotopes are recognized. Rhenium metal is prepared by reducing ammonium perrhentate with hydrogen at elevated temperatures. It has other useful properties. The usual commercial form of the element is a powder, but it can be consolidated by pressing and resistance sintering in a vacuum or hydrogen atmosphere.
Annealed rhenium is very ductile, and can be bent, coiled, or rolled.
Rhenium is used as an additive to tungsten and molybdenum-based alloys to impart useful properties. It is widely used for filaments for mass spectrographs and ion gages. Rhenium-molybdenum alloys are superconductive at 10 K. Rhenium is also used as an electrical contact material as it has good wear resistance and withstands arc corrosion. Thermocouples made of Re-W are used for measuring temperatures up to 2200C, and rhenium wire is used in photoflash lamps for photography. Rhenium catalysts are exceptionally resistant to poisoning from nitrogen, sulfur, and phosphorus, and are used for hydrogenation of fine chemicals.