Bonded niobium silicide and molybdenum silicide composite articles using semi-solid 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 is a semi-solid braze that comprises a first component and a second component, said first component comprising a first element and a second metallic element, wherein said first element is one of titanium, palladium, zirconium, niobium, germanium, silicon, and hafnium, wherein said second metallic element is one of titanium, palladium, zirconium, niobium, hafnium, aluminum, chromium, vanadium, platinum, gold, iron, nickel, and cobalt, said second metallic element being different from said first element, and wherein said second component has a melting temperature greater than 1450° C. and comprises at least one of niobium, molybdenum, titanium, hafnium, silicon, boron, aluminum, tantalum, germanium, vanadium, tungsten, zirconium, and chromium.

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 is a semi-solid braze that comprises a first component and a second component, said first component comprising a first element and a second metallic element, wherein said first element is one of titanium, palladium, zirconium, niobium, germanium, silicon, and hafnium, wherein said second metallic element is one of titanium, palladium, zirconium, niobium, hafnium, aluminum, chromium, vanadium, platinum, gold, iron, nickel, and cobalt, said second metallic element being different from said first element, and wherein said second component has a melting temperature of at least about 1450° C. and comprises at least one of niobium, molybdenum, titanium, hafnium, silicon, boron, aluminum, tantalum, germanium, vanadium, tungsten, zirconium, and chromium.

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 being a semi-solid braze that comprises a first component and a second component, the first component having a first component melting temperature comprising a first element and a second metallic element, the first 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 colbalt, the first element being different from the second metallic element, and the second component having a second component melting temperature of at least about 1450° C. and comprising at least one of niobium, molybdenum, titanium, hafnium, silicon, boron, aluminum, tantalum, germanium, vanadium, tungsten, zirconium, and chromium;
• 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 about 20° C. above the first component melting temperature and less than the second component melting temperature;
• 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.