Rhenium

Density - 21.02 grams per cubic centimeter

Melting point - 3,180°C (5,760°F)

Boiling point - 5,630°C (10,170°F)

 

These melting and boiling point numbers are among the highest to be found for any of the chemical elements.  When heated, unlike most metals, it does not have a ductile/brittle transition. It remains ductile up to its melting point. The unusual behavior of rhenium means that it can be heated and recycled many times without breaking apart. It has an extremely high re-crystallization temperature (2800°C) giving it excellent creep resistance.

 

Rhenium is one of the rarest elements in the world with an average crystal abundance of less than 0.5 ppm. It does not occur free in Nature, but is generally associated to molybdenites, MoS2 ores, that contain about 0.002 to 0.02% of this element. The molybdenites can be found in copper sulfide ores which represent an important commercial source of the element.

 

The two most important uses of rhenium are in super-alloys and platinum-rhenium catalysts. The aircraft industry is the major consumer of Re containing super-alloys. They are used primarily in single-crystal turbine blades in the hot sections of turbine engines.  Platinum-rhenium catalysts are used to produce high-octane, lead-free gasoline. Rhenium is also used in tungsten-rhenium and molybdenum-rhenium alloys for electrical contact points, flashbulbs, heating elements, metallic coatings, temperature controls, thermocouples, vacuum tubes, and x-ray tubes and targets.