Bonded niobium silicide and molybdenum silicide composite articles using brazes

An airfoil having a melting temperature of at least about 1500° C., said airfoil comprising:

• a) a first piece comprising one of a first niobium-based refractory metal intermetallic composite and a first molybdenum-based refractory metal intermetallic composite, wherein said first niobium-based refractory metal intermetallic composite comprises titanium, hafnium, silicon, chromium, and niobium, and said first molybdenum-based refractory metal intermetallic composite comprises molybdenum, silicon, and at least one of chromium and boron;
• and
• b) a second piece joined by a braze to said first piece, said second piece comprising one of a second niobium-based refractory metal intermetallic composite and a second molybdenum-based refractory metal intermetallic composite, wherein said second niobium-based refractory metal intermetallic composite comprises titanium, hafnium, silicon, chromium, and niobium, and said second molybdenum-based refractory metal intermetallic composite comprises molybdenum, silicon, and at least one of chromium and boron, and wherein said braze comprises a first metallic element and a second metallic element, wherein said first metallic element is one of titanium, palladium, zirconium, niobium, and hafnium, and wherein said second metallic element is one of titanium, palladium, zirconium, niobium, hafnium, aluminum, chromium, vanadium, platinum, gold, iron, nickel, and cobalt, wherein said first metallic element is different from said second metallic element.

A turbine assembly having at least one component, said at least one component having a melting temperature of at least about 1500° C. and comprising:

• a) a first piece comprising one of a first niobium-based refractory metal intermetallic composite and a first molybdenum-based refractory metal intermetallic composite, wherein said first niobium-based refractory metal intermetallic composite comprises titanium, hafnium, silicon, chromium, and niobium, and said first molybdenum-based refractory metal intermetallic composite comprises molybdenum, silicon, and at least one of chromium and boron;
• and
• b) a second piece joined by a braze to said first piece, said second piece comprising one of a second niobium-based refractory metal intermetallic composite and a second molybdenum-based refractory metal intermetallic composite, wherein said second niobium-based refractory metal intermetallic composite comprises titanium, hafnium, silicon, chromium, and niobium, and said second molybdenum-based refractory metal intermetallic composite comprises molybdenum, silicon, and at least one of chromium and boron, and wherein said braze comprises a first metallic element and a second metallic element, wherein said first metallic element is one of titanium, palladium, zirconium, niobium, and hafnium, and wherein said second metallic element is one of titanium, palladium, zirconium, niobium, hafnium, aluminum, chromium, vanadium, platinum, gold, iron, nickel, and cobalt, wherein said first metallic element is different from said second metallic element.

A method of making an article, the article having a melting temperature of at least about 1500° C. and comprising a first piece and a second piece that are joined together by a braze, wherein the first piece and second piece each comprise one of a niobium-based refractory metal intermetallic composite and a molybdenum-based refractory metal intermetallic composite, wherein the niobium-based refractory metal intermetallic composite comprises titanium, hafnium, silicon, chromium, and niobium and the molybdenum-based refractory metal intermetallic composite comprises molybdenum, silicon, and at least one of chromium and boron, the method comprising the steps of:

• a) providing the first piece and the second piece such that the first piece and the second piece form an interface therebetween;
• b) providing a braze to the interface between the first piece and the second piece, the braze having a melting temperature and comprising a first metallic element and a second metallic element, the first metallic element being one of titanium, palladium, zirconium, niobium, and hafnium, and the second metallic element being one of titanium, palladium, zirconium, niobium, hafnium, aluminum, chromium, vanadium, platinum, gold, iron, nickel, and cobalt, wherein the first metallic element is different from the second metallic element;
• c) heating the first piece, the second piece, and the braze to a first temperature for a first predetermined hold time, the first temperature being at least 20° C. above the melting temperature of the braze;
• and
• d) further heating the first piece, the second piece, and the braze to a temperature up to about 1450° C. for a second predetermined hold time, thereby joining the first piece and the second piece at the interface and forming the article.