Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1572364 | Materials Characterization | 2008 | 8 Pages |
Abstract
Turbine components from conventionally cast nickel-base alloy René 80 show different hot cracking susceptibilities depending on their heat treatment conditions leading to slightly different microstructures. Electron probe micro-analysis, focused ion beam technique and analytical transmission electron microscopy were applied to reveal and identify grain boundary precipitates and the γ-γâ²-microstructure. The distribution of borides along grain boundaries was evaluated statistically by quantitative metallography. The following features could be correlated with an increase of cracking susceptibility: i) Increasing grain size, ii) increasing fraction of grain boundaries with densely spaced borides, iii) lack of secondary γâ²-particles in matrix channels between the coarse cuboidal γâ²-precipitates. The latter feature seems to be responsible for linking-up of cracked grain boundary precipitates which occurred as an additional cracking mechanism after one heat treatment, whereas decohesion at the boride-matrix-interface in the heat affected zone of laser-drilled holes was observed for both heat treatments.
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Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
W. Ãsterle, S. Krause, T. Moelders, A. Neidel, G. Oder, J. Völker,