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(UMI)AAI8127607 eng Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981. http://hdl.handle.net/2142/68652 Hindin, Barry Scott 2014-12-14T16:00:46Z 2014-12-14T16:00:46Z 10000-01-01 1981 1981 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. Made available in DSpace on 2014-12-14T16:00:46Z (GMT). No. of bitstreams: 1 8127607.pdf: 4316117 bytes, checksum: 77e63e66cc601e9685830d20ccb05a6d (MD5) Previous issue date: 1981 Embargo set by: Seth Robbins for item 68830 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 175 p. Engineering, Metallurgy Fracture Kinetics of Hydrogen Embrittled Niobium text Metallurgy and Mining Engineering Metallurgical Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.