Creep Properties of Directionally Solidified Nb-Modified Ni-Base Superalloy, Mar-M247

The Ni-base superalloy Mar-M247 is widely used for elevated-temperature applications in both equiaxed and directionally solidified forms. The alloy contains about 3 wt.% Ta. Due to the cost and density of Ta, an atom-for-atom substitution of Nb for Ta was investigated. The creep properties in the te...

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Bibliographic Details
Published in:Journal of materials engineering and performance 2018-11, Vol.27 (11), p.5744-5751
Main Authors: Costa, A. M. S., Hawk, E., Dansbury, J., Nunes, C. A., Fuchs, G. E.
Format: Article
Language:English
Subjects:
Characterization and Evaluation of Materials
Chemistry and Materials Science
COMPARATIVE EVALUATIONS
Corrosion and Coatings
CREEP
Engineering Design
HEAT RESISTING ALLOYS
MATERIALS SCIENCE
MICROSTRUCTURE
NICKEL ALLOYS
NIOBIUM ADDITIONS
PRESSURE RANGE MEGA PA 100-1000
Quality Control
Reliability
Safety and Risk
STRESSES
TEMPERATURE RANGE 1000-4000 K
Tribology
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Summary:The Ni-base superalloy Mar-M247 is widely used for elevated-temperature applications in both equiaxed and directionally solidified forms. The alloy contains about 3 wt.% Ta. Due to the cost and density of Ta, an atom-for-atom substitution of Nb for Ta was investigated. The creep properties in the temperature range of 750-950 °C and stresses ranging from 200 to 1000 MPa were determined. In general, the creep properties of the Nb-modified Mar-M247 material were very similar to those of Mar-M247 samples at 750 and 850 °C. However, the Mar-M247 samples exhibited superior creep properties at 950 °C. The lower creep properties of the Nb-modified Mar-M247 are likely due to the finer starting microstructure, more rapid coarsening rate of the γ ′ and reduced γ ′ strengthening effect (i.e., APB energy) of Nb, compared to Ta. No evidence of TCP phases was observed in either alloy.
ISSN:1059-9495
1544-1024
DOI:10.1007/s11665-018-3699-6