1 columbium niobium and tantalum by larry d cunningham nb is vital as an alloying element in group was 5 05 million kilograms the overall goal for steels superalloys aircraft turbine engines greatest demand industrialized countries critical to united states because of its defense related uses aerospace energy transportation industries acceptable substitutes are available some applications but most cases they less desirable ta a refractory metal that ductile easily fabricated has high melting point highly resistant corrosion acids good conductor heat electricity also missiles radio communications substitution made at either performance or economic penalty domestic resources low grade mineralogically complex not currently commercially recoverable last significant mining during korean conflict when increased military resulted ore shortages 1995 continued
