L12-phase cutting during high temperature and low stress creep of a Re-containing Ni-base single crystal superalloy

In the present study, we investigate dislocation processes in a Ni-base single crystal superalloy (LEK94) after high temperature and low stress creep. Specimens were creep deformed at 240 MPa and 980 °C to a strain of 20%. We use diffraction contrast transmission electron microscopy (TEM) to show th...

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Bibliographic Details
Published in:Journal of materials science 2007-06, Vol.42 (11), p.3951-3957
Main Authors: KOSTKA, A, MÄLZER, G, EGGELER, G, DLOUHY, A, REESE, S, MACK, T
Format: Article
Language:English
Subjects:
Applied sciences
Creep
Creep (materials)
Cross-disciplinary physics: materials science
rheology
Cutting
Deformation
Exact sciences and technology
High temperature
Materials science
Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology
Metals. Metallurgy
Nickel base alloys
Organic chemistry
Other topics in materials science
Physics
Single crystals
Superalloys
Superdislocations
Transmission electron microscopy
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Summary:In the present study, we investigate dislocation processes in a Ni-base single crystal superalloy (LEK94) after high temperature and low stress creep. Specimens were creep deformed at 240 MPa and 980 °C to a strain of 20%. We use diffraction contrast transmission electron microscopy (TEM) to show that two γ-channel dislocations with different Burgers vectors combine and form a super dislocation that shears the γ′-particle. This type of cutting event has now been observed for three single crystal superalloys with different alloy chemistry (CMSX-4, CMSX-6 and LEK94 in the present work) and we therefore conclude that it represents a generic elementary dislocation process which governs high temperature (around 1000 °C) and low stress (around 240 MPa) creep. The present paper provides microstructural evidence for this type of cutting processes and discusses the results in the light of previous work published in the literature.
ISSN:0022-2461
1573-4803
DOI:10.1007/s10853-006-0166-9