Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1580776 | Materials Science and Engineering: A | 2009 | 6 Pages |
Abstract
The microstructure of nickel-base superalloys changes significantly during creep. The strengthening γâ²-precipitates coarsen directionally and dislocation networks develop at the interfaces between γâ²-precipitates and γ-matrix. Coherency stresses due to the lattice misfit between γ and γⲠphase act as the driving force for these microstructural changes. The measurement of the lattice constant of the γ-matrix and γâ²-phase by X-ray diffraction before and after creep experiments allows the changes of internal stress and strain states during creep to be revealed. In this work, three experimental alloys with systematically varied amounts of lattice misfit were studied. It was found that the separation of X-ray peaks of γ and γⲠafter creep is directly dependent on the amount of lattice misfit. Also the distortion of the lattice, visible in the broadening of the respective rocking curves, was measured and found to be dependent on the lattice misfit as long as the γ/γâ²-interfaces stay coherent. The lattice misfit is directly influenced by the alloy composition. Rhenium and ruthenium decrease the lattice misfit and modify the coherency stresses between γ- and γâ²-phase accordingly.
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
Florian Pyczak, Steffen Neumeier, Mathias Göken,