Mechanical properties of silver at low temperatures
In this study the authors obtained detailed information about the stress, strain, strain rate, and temperature-dependence of plastic flow in cold-worked high-purity (99.99 wt%) silver. They performed tensile and creep tests at temperatures from 77 K to 473 K and at strain rates of 10/sup -8/ to 10/sup -3/ per second. It is generally agreed that silver, like most facecentered-cubic metals, deforms at low temperatures by the dislocation intersection mechanism. The rate-controlling process in the intersection mechanism is the overcoming of obstacles (forest dislocations) by glide dislocations. The process involves the formation of jogs and constrictions, with an activation energy appropriate to those processes. The amount of local deformation per successful event is expressed by an activation volume, or activation area times the Burgers vector. As the density of the forest increases--at higher strains and lower temperatures--the activation area is expected to decrease. At temperatures near half the absolute melting point (617 K) the metal begins to deform predominantly by climb-controlled dislocation creep. The data generated thus far show some interesting phenomena concerning the transition between these two mechanisms.
- Research Organization:
- Materials Science Division, Lawrence Livermore National Laboratory, Livermore, California 94550
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5531371
- Journal Information:
- Scr. Metall.; (United States), Journal Name: Scr. Metall.; (United States) Vol. 17:1; ISSN SCRMB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360103* -- Metals & Alloys-- Mechanical Properties
ACTIVATION ENERGY
CREEP
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEFORMATION
DISLOCATIONS
ELEMENTS
ENERGY
LINE DEFECTS
MATERIALS TESTING
MECHANICAL PROPERTIES
MECHANICAL TESTS
MEDIUM TEMPERATURE
MELTING POINTS
METALS
MICROSTRUCTURE
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SILVER
STRAIN RATE
STRAINS
STRESS ANALYSIS
STRESSES
TEMPERATURE DEPENDENCE
TEMPERATURE EFFECTS
TENSILE PROPERTIES
TESTING
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
TRANSITION TEMPERATURE