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Title:Hydrogen segregation, defects, and interactions with dislocations in nickel and aluminum
Author(s):Sirois, Ernest Joseph, Jr
Doctoral Committee Chair(s):Birnbaum, Howard K.
Department / Program:Materials Science and Engineering
Discipline:Materials Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):Engineering, Metallurgy
Engineering, Materials Science
Abstract:Deformation experiments were performed to determine the effects of hydrogen and carbon on the activation parameters for dislocation slip in macroscopic nickel tensile specimens. The results show that hydrogen increases the dislocation mobility in Ni and in Ni-H alloys by reducing the activation enthalpy for dislocation motion and carbon reduces the mobility by increasing the enthalpy. Stress relaxation results show that the relaxation proceeds in three stages, which may be characterized by different activation areas.
Secondary Ion Mass Spectroscopy experiments were performed to directly study the hydrogen (deuterium) distribution in several metal-hydrogen systems. Enhanced hydrogen (deuterium) concentration was observed at most grain boundaries, but not at coherent twin boundaries in Ni-H alloys which were exposed to low energy hydrogen (deuterium) plasma bombardment. Hydrogen (deuterium) was readily observed to segregate to a minority of grain boundaries in deformed, gaseous hydrogen charged, and low temperature aged Ni-H alloys.
Small angle X-ray scattering experiments were performed to study hydrogen related defects in Ni-H and in Al-H alloys. Results for Al-H alloys show defects which exhibit anisotropic scattering, typical of platelet defects. Ni-H alloys show defects which exhibit isotropic scattering, suggestive of spherical void defects.
Issue Date:1990
Type:Text
Language:English
URI:http://hdl.handle.net/2142/20816
Rights Information:Copyright 1990 Sirois, Ernest Joseph, Jr
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9114415
OCLC Identifier:(UMI)AAI9114415


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