Dissertation/Thesis Abstract

The role of twin boundaries in fatigue microcrack initiation in an advanced nickel-based alloy
by Stein, Clayton A., Ph.D., Carnegie Mellon University, 2015, 111; 3746533
Abstract (Summary)

The study of fatigue in metals, and fatigue initiation specifically, lends itself to analysis via an emerging set of characterization and modeling tools that describe polycrystals on the meso- or microstructural length scale. These include three-dimensional characterization techniques, elastic anisotropic stress models, new approaches to the statistical description of stress and strain distributions, synthetic microstructure modeling, and improved tools for manipulating the large datasets generated. A specific example of analysis in both 2D and 3D of fatigue cracks in a nickel-based superalloy is given where all the cracks are effectively coincident with coherent twin boundaries. A spectral method is used to analyze the stress state based on a fully anisotropic elastic calculation. The results indicate that, although a high resolved shear stress is associated with the locations of the observed cracks, the length of the trace of the twin boundary is more strongly correlated with crack formation. Twin boundaries

Indexing (document details)
Advisor:
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School: Carnegie Mellon University
School Location: United States -- Pennsylvania
Source: DAI-B 77/07(E), Dissertation Abstracts International
Source Type: DISSERTATION
Subjects: Materials science
Keywords: Crack initiation, Fatigue, Microstructure, Superalloys
Publication Number: 3746533
ISBN: 9781339399676
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