Alloy and structural optimization of a directionally solidified lamellar eutectic alloy. [Ni--20% Nb--2. 5% Al--6% Cr]
Mechanical property characterization tests of a directionally solidified Ni--20 percent Cb--2.5 percent Al--6 percent Cr cellular eutectic turbine blade alloy demonstrated excellent long time creep stability and indicated intermediate temperature transverse tensile ductility and shear strength to be somewhat low for turbine blade applications. Alloy and structural optimization significantly improves these off--axis properties with no loss of longitudinal creep strength or stability. The optimized alloy--structure combination is a carbon modified Ni--20.1 percent Cb--2.5 percent Al--6.0 percent Cr--0.06 percent C composition processed under conditions producing plane front solidification and a fully-lamellar microstructure. With current processing technology, this alloy exhibits a creep-rupture advantage of 39 C over the best available nickel base superalloy, directionally solidified MAR M200+ Hf. While improved by about 20 percent, shear strength of the optimized alloy remains well below typical superalloy values. (auth)
- Research Organization:
- Pratt and Whitney Aircraft, East Hartford, CT (USA)
- DOE Contract Number:
- NAS3-17811
- OSTI ID:
- 7318479
- Report Number(s):
- N-76-22355; NASA-CR-135000; PWA-5300; TRN: 77-009601
- Country of Publication:
- United States
- Language:
- English
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