One method of improving the potential for durability, reliability, and performance of land-based gas turbine hot-stage buckets is through the use of composite hardware. Airfoil vanes would have directionally solidified (DS) nickel-base superalloys for optimizing creep/rupture properties while dovetail regions would use P/M superalloys for high tensile strength and ductility. The limiting item for this type of technology is the critical airfoil to dovetail bondline. This program will demonstrate both the feasibility of producing composite structures using P/M and DS alloys and the excellent properties that can be achieved at the critical powder-to-cost alloy bondline. Using hot isostatic pressing, two powder alloys and three DS alloys were diffusion bonded together. A total of six composite structures were evaluated. Alloys included P/M version of low-carbon Astroloy and PA-101 while DS alloys included MAR-M200 plus Hf, Rene 80H, and a modified version of Rene 150. Three separate solution temperatures were used to HIP diffusion bond each DS/powder alloy combination. Subsequent alloy and bondline screening to assess the optimum composite structure was done using both high-temperature tensile testing and metallurgical evaluations. Optimum structures were further evaluated using low-cycle fatigue testing on 45- and 90-degree bond joints in conjunction with electron microprobe and transmission electron microscopy of the composite bond line.
HIP diffusion bonding of P/M alloys for composite land-based gas turbine buckets
Diffusionsschweissen von Pulvermetallegierungen durch HIP bei der Herstellung von Gasturbinengehaeusen
Annual Powder Metallurgy Conf. Proc., MPIF-APMI ; 41 , Jul ; 561-578
1986
18 Seiten, 15 Bilder, 4 Tabellen, 3 Quellen
Conference paper
English
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