Award Date

1-1-2006

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Committee Member

Ajit K. Roy

Number of Pages

90

Abstract

Nb7.5Ta, a candidate refractory material for use in the HI, decomposition process, has been tested for evaluation of its tensile properties and corrosion resistance. The results of tensile testing within a temperature range of ambient to 400°C revealed a gradual drop in tensile strength with increasing temperature. However, reduced failure strain was observed at temperatures up to 300°C, suggesting the occurrence of dynamic strain aging (DSA) behavior. The characterization of the tensile specimens by transmission electron microscopy showed somewhat higher dislocation density at 300°C that could be the result of the DSA effect. Corrosion studies under a slow strain rate condition in an acidic solution exhibited enhanced cracking tendency at 90°C, suggesting a detrimental effect of higher temperature on the cracking susceptibility. No failures were observed under a constant-load condition. An application of a cathodic controlled potential to the test specimen resulted in enhanced cracking tendency in terms of failure strain. The morphology of failure, determined by a scanning electron microscope, was ductile in all tested specimens.

Keywords

Characterizaton; Decomposition; Hix; Nb7; Process

Controlled Subject

Mechanical engineering; Materials science

File Format

pdf

File Size

2693.12 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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