Influence of phase composition and microstructure on the high temperature creep properties of a model single crystal nickel-base superalloy: An atom probe/AEM study

Journal Article · Mon May 01 04:00:00 EDT 1995 · Acta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-7151(94)00357-N· OSTI ID:55347

Jayaram, R; Miller, M K ^[1]

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1. Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

Atom probe field ion microscopy (APFIM) and analytical electron microscopy (AEM) have been used to characterize the microstructure of as-quenched and creep-tested model single crystal nickel-base superalloys having the nominal bulk composition Ni-x at.% Mo-2.0% Ta-13.7% Al (x = 7.8--9.2%). The results showed that Ta partitioned preferentially to the {gamma}{prime} phase whereas Mo partitioned to the {gamma} matrix. Atom probe composition profiles across {gamma}-{gamma}{prime} interfaces did not reveal any evidence of solute segregation and statistical analyses of the data did not indicate ultrafine solute clusters in the {gamma} matrix. Acicular {delta} phase precipitates were detected in number densities approximately one order of magnitude higher in the 9.2% Mo alloy as compared to the 8.6 and 8.8% Mo alloy. There was some indication that the DO{sub 22}-ordered {gamma}{double_prime} phase is stable at 982 C, the temperature at which the creep tests were performed. The absence of interfacial solute segregation and clustering in the {gamma} matrix suggested that the high creep life of this model alloy system is influenced by the nature of the dislocation network at the {gamma}-{gamma}{prime} interface with a possible strengthening contribution from the DO{sub 22}-ordered phase.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 55347
• Journal Information: Acta Metallurgica et Materialia, Journal Name: Acta Metallurgica et Materialia Journal Issue: 5 Vol. 43; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CREEP
DISLOCATIONS
ELECTRON MICROSCOPY
INTERFACES
ION MICROSCOPY
METALLURGICAL EFFECTS
MICROSTRUCTURE
MOLYBDENUM ALLOYS
NICKEL BASE ALLOYS
PHASE STUDIES
PRECIPITATION
TANTALUM ALLOYS