Surface oxide softening of niobium single crystals

Journal Article · Tue Mar 01 00:00:00 EST 1977 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(77)90151-1· OSTI ID:7295278

Sethi, V K; Gibala, R

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.

• Research Organization: Case Western Reserve Univ., Cleveland
• OSTI ID: 7295278
• Journal Information: Acta Metall.; (United States), Vol. 25:3, Issue 3
• Country of Publication: United States
• Language: English

Related Subjects

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 &amp; Alloys- Mechanical Properties
360105 - Metals &amp; Alloys- Corrosion &amp; Erosion