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Joint Development of a Fourth Generation Single Crystal SuperalloyA new, fourth generation, single crystal superalloy has been jointly developed by GE Aircraft Engines, Pratt & Whitney, and NASA. The focus of the effort was to develop a turbine airfoil alloy with long-term durability for use in the High Speed Civil Transport. In order to achieve adequate long-time strength improvements at moderate temperatures and retain good microstructural stability, it was necessary to make significant composition changes from 2nd and 3rd generation single crystal superalloys. These included lower chromium levels, higher cobalt and rhenium levels and the inclusion of a new alloying element, ruthenium. It was found that higher Co levels were beneficial to reducing both TCP precipitation and SRZ formation. Ruthenium caused the refractory elements to partition more strongly to the ' phase, which resulted in better overall alloy stability. The final alloy, EPM 102, had significant creep rupture and fatigue improvements over the baseline production alloys and had acceptable microstructural stability. The alloy is currently being engine tested and evaluated for advanced engine applications.
Document ID
Document Type
Technical Memorandum (TM)
Walston, S. (General Electric Aircraft Engines Cincinnati, OH, United States)
Cetel, A. (Pratt and Whitney Aircraft East Hartford, CT, United States)
MacKay, R. (NASA Glenn Research Center Cleveland, OH, United States)
OHara, K. (General Electric Aircraft Engines Lynn, MA, United States)
Duhl, D. (Pratt and Whitney Aircraft East Hartford, CT, United States)
Dreshfield, R. (NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
September 7, 2013
Publication Date
December 1, 2004
Subject Category
Metals and Metallic Materials
Report/Patent Number
Meeting Information
10th International Symposium on Superalloys(Champion, PA)
Funding Number(s)
WBS: WBS 22-714-04-06
Distribution Limits
Work of the US Gov. Public Use Permitted.

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