The result of this quest are the Heavy Tungsten Alloys. Tungsten heavy alloys are ideal for high-density applications or for use in radiation shielding. Heavy metal tungsten alloys are 90% to 97% pure tungsten in a matrix of nickel/copper or nickel/iron. Heavy metal alloys are pseudo alloys of tungsten with a nickel iron or nickelcopper matrix. They are produced by powder metal and sintering processes.