Coated columbium

Claim 1

A DUPLEX COATED COLUMBIUM-BASE METAL PRODUCTS CHARACTERIZED BY RESISTANCE TO SEVERE THERMAL AND MECHANICAL STRESSES, OXIDATION-RESISTENCE, AND SELF-HEALING, WHICH COMPRISES; A REFACTORY-METAL BASE SELECTED FROM THE GROUP CONSISTING OF COLUMBIUM AND COLUMBIUM-BASE ALLOYS; A FIRST COATING CONTIGUOUS TO SAID BASE COMPRISING 30 TO 60 WEIGHT PERCENT COLUMBIUM, 10 TO 40 WEIGHT PERCENT TITANIUM, 5 TO 15 WEIGHT PERCENT CHORMIUM, 2 TO 10 WEIGHT PERCENT ALUMINUM, UP TO 10 WEIGHT PERCENT VANADIUM, UP TO 20 WEIGHT PERCENT NICKEL, UP TO 20 WEIGHT PERCENT IRON, AND THE REMAINDER INCIDENTAL IMPURTIES, SAID FIRST COATING AND THE REMAINDER INCIDENTAL IMPURITIES, SAID FIRST COATING BEING MISCIBLE IN SAID REFRACTORY-METAL BASE AND HAVING SUBSTANTIALLY SIMILAR COEFFICIENTS OF EXPANSION AND MODULI OF E;ASTICITY AS SAID REFRACTORY-METAL BASE; AND A SECOND COATING COMPRISING BETWEEN 10 AND 40 ATOMIC PERCENT OF AT LEAST ONE MATAL SELECTED FROM THE GROUP CONSISTING OF MOLYBDENUM, TUNGSTEN, TATALUM, COLUMBIUM AND VANADIUM, BETWEEN 20 AND 65 ATOMIC PERCENT SILICON, BETWEEN 2 AND 26 ATOMIC PERCENT OF AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF CHROMIUM, TITANIUM AND ZIRCONIUM, BETWEEN 2 AND 25 ATOMIC PERCENT BORON, BETWEEN 3 AND 30 ATOMIC PERCENT ALUMINUM AND THE REMAINDER INCIDENTAL IMPURITIES.