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Title: Surface oxide softening of niobium single crystals

Abstract

The effect of thin (<160 mn) anodic oxide films on the mechanical behavior of single crystals of niobium was investigated. At 295/sup 0/K, oxide films cause hardening. At lower temperatures, the oxide films reduce the critical resolved shear stress and cause serrated flow. When oxide-coated niobium is prestrained into stage 1 at 295/sup 0/K, the flow stress at lower temperatures is further reduced, the ductility is increased, the serrations disappear, and three-stage work hardening is observed. A model involving preferential generation and motion of edge dislocations from the oxide-metal interface is used to explain the results. Supporting evidence obtained from slip trace analysis, transmission electron microscopy of dislocation substructures, and etch pitting of near-surface dislocations is presented.

Authors:
;
Publication Date:
Research Org.:
Case Western Reserve Univ., Cleveland
OSTI Identifier:
7295278
Resource Type:
Journal Article
Journal Name:
Acta Metall.; (United States)
Additional Journal Information:
Journal Volume: 25:3; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; NIOBIUM; MECHANICAL PROPERTIES; DISLOCATIONS; DUCTILITY; FILMS; HARDNESS; INTERFACES; LOW TEMPERATURE; MEDIUM TEMPERATURE; MONOCRYSTALS; OXIDES; CHALCOGENIDES; CRYSTAL DEFECTS; CRYSTAL STRUCTURE; CRYSTALS; ELEMENTS; LINE DEFECTS; METALS; OXYGEN COMPOUNDS; REFRACTORY METALS; TENSILE PROPERTIES; TRANSITION ELEMENTS; 360103* - Metals & Alloys- Mechanical Properties; 360105 - Metals & Alloys- Corrosion & Erosion

Citation Formats

Sethi, V K, and Gibala, R. Surface oxide softening of niobium single crystals. United States: N. p., 1977. Web. doi:10.1016/0001-6160(77)90151-1.
Sethi, V K, & Gibala, R. Surface oxide softening of niobium single crystals. United States. https://doi.org/10.1016/0001-6160(77)90151-1
Sethi, V K, and Gibala, R. 1977. "Surface oxide softening of niobium single crystals". United States. https://doi.org/10.1016/0001-6160(77)90151-1.
@article{osti_7295278,
title = {Surface oxide softening of niobium single crystals},
author = {Sethi, V K and Gibala, R},
abstractNote = {The effect of thin (<160 mn) anodic oxide films on the mechanical behavior of single crystals of niobium was investigated. At 295/sup 0/K, oxide films cause hardening. At lower temperatures, the oxide films reduce the critical resolved shear stress and cause serrated flow. When oxide-coated niobium is prestrained into stage 1 at 295/sup 0/K, the flow stress at lower temperatures is further reduced, the ductility is increased, the serrations disappear, and three-stage work hardening is observed. A model involving preferential generation and motion of edge dislocations from the oxide-metal interface is used to explain the results. Supporting evidence obtained from slip trace analysis, transmission electron microscopy of dislocation substructures, and etch pitting of near-surface dislocations is presented.},
doi = {10.1016/0001-6160(77)90151-1},
url = {https://www.osti.gov/biblio/7295278}, journal = {Acta Metall.; (United States)},
number = 3,
volume = 25:3,
place = {United States},
year = {1977},
month = {3}
}