 Nickel-based superalloys of rhenium are used in the combustion chambers, turbine blades, and exhaust nozzles of jet engines. These alloys contain up to 6 % rhenium, making jet engine construction the largest single use for the element, with the chemical industry's catalytic uses being next-most important. Because of the low availability relative to demand, rhenium is among the most expensive of metals, with an average price of approximately US $ 2,750 per kilogram (US $ 85.53 per troy ounce) as of April 2015; it is also of critical strategic military importance, for its use in high performance military jet and rocket engines.
