All refractory metals, except osmium and iridium, have the highest melting temperatures and lowest vapor pressures of all metals. This Article discusses the commercial applications, and production procedures of refractory metals and alloys. These procedures include fabrication, machining, forming, cleaning, joining, and coatings. The Article also presents information on, and specifications for, the following metals and their alloys: niobium, tantalum, molybdenum, tungsten, rhenium, and refractory metal fiber-reinforced composites. It discusses the processes involved in their production, their mechanical properties, physical properties, thermal properties, electrical properties, chemical properties, applications, and corrosion resistance.