Effects of thin anodic films on cyclic deformation of tungsten

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5289314

Bowman, K J

The dynamics of edge and screw dislocation motion as a function of temperature play a decisive role in the mechanical response of bcc metals. Cyclic deformation over a range of plastic-strain levels was used to investigate many aspects of the cyclic stress-strain response of tungsten single crystals at room temperature. The results of this investigation fully support a two-dislocation model of deformation for bcc metals at low homologous temperatures (T less than or equal to 0.15T/sub m/). The occurrence of stress asymmetry and cyclic stress-strain behavior which fits a two-dislocation model are demonstrated in crystals of several orientations. The results indicate that the nearly isotropic elastic response of tungsten produces the nearly ideal stress asymmetry expected for bcc crystals. Thin anodic films (approx. 80 nm) were utilized to determine the effects of surface modification on the cyclic stress-strain behavior of tungsten. At cyclic microstrains, the anodization of tungsten produces a large reversible hardening effect. At cyclic macrostrains the anodization of tungsten produces a smaller, less reversible softening effect. These two effects are explained in terms of dislocation multiplication and annihilation processes

• Research Organization: Michigan Univ., Ann Arbor (USA)
• OSTI ID: 5289314
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ANODIZATION
BCC LATTICES
CHEMICAL COATING
CORROSION PROTECTION
CRYSTAL DEFECTS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
CUBIC LATTICES
DEFORMATION
DEPOSITION
DISLOCATIONS
ELASTICITY
ELECTROCHEMICAL COATING
ELECTROLYSIS
ELEMENTS
FILMS
LINE DEFECTS
LYSIS
MECHANICAL PROPERTIES
METALS
MONOCRYSTALS
STRAINS
STRESS ANALYSIS
SURFACE COATING
TENSILE PROPERTIES
TRANSITION ELEMENTS
TUNGSTEN