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|Title:||Fracture Kinetics of Hydrogen Embrittled Niobium|
|Author(s):||Hindin, Barry Scott|
|Department / Program:||Metallurgy and Mining Engineering|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Kinetics of crack propagation in hydrogen charged niobium were studied in the temperature range 77 to 303 K and for hydrogen concentrations between 0.068 and 3.2 at.%. Crack velocities between 10('-8) and 10('-2) m/s were determined as a function of the Mode I stress intensity factors using single edge notch and double torsion specimens. Validity of the double torsion technique was established using a variety of methods including photoelastic analysis of the stresses in the plane normal to the specimen's crack surface.
Increasing, decreasing and constant K(,I) tests were carried out and the 1nV versus K(,I) data exhibited various behavior depending upon the type of loading. Linking up of fracturing hydrides were shown to be responsible for a unique three region (V-K) behavior which occurred only at intermediate temperatures for decreasing K(,I) tests. Analysis of the temperature dependence for Stage II during constant K(,I) tests indicated that the cracking kinetics are controlled by hydrogen diffusion to the crack tip. Differences between crack velocities in deuterium and hydrogen charged specimens were consistent with the isotopic differences in their diffusion coefficients. Fracture surfaces of the test specimens were examined and shown to exhibit features consistent with their crack velocity behavior.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981.
|Date Available in IDEALS:||2014-12-14|
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Dissertations and Theses - Metallurgy and Mining Engineering
Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois