Coalescence of large grain boundary cavities in silver during tension creep

Journal Article · Mon May 01 00:00:00 EDT 1978 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(78)90025-1· OSTI ID:6344757

Goods, S H; Nix, W D

An experimental technique for implanting water vapor bubbles in silver was used to produce a uniform distribution of very large cavities along the grain boundaries of high purity silver. By implanting these very large bubbles prior to the onset of creep, the kinetics of the final stages of creep cavity growth and coalescence can be studied. The stress and temperature dependence for the creep-rupture of silver with grain boundary cavities initially 12 ..mu..m in diameter and spaced 20 ..mu..m apart has been determined for the temperature range 200 to 400/sup 0/C. It is found that the time to rupture depends on the applied stress: t/sub r/ approx. sigma/sup -9/. The activation energy for creep rupture of silver with this microstructure is 199 kJ/mol above 300/sup 0/C and about 103 kJ/mol below that temperature. The stress and temperature dependence for the creep-rupture of the embrittled silver appears to be identical with the stress and temperature dependence for the creep of silver itself suggesting that the final stages of cavity growth consists of the plastic tearing of the ligament material between the cavities. Scanning electron microscopy of the fracture surfaces reveals brittle, intergranular grain boundary facets. These facets exhibit uniformly distributed dimples, the spacing of which corresponds to the initial gas bubble spacing, indicating that fracture occurs solely by the growth of the pre-existing gas bubbles.

• Research Organization: Stanford Univ., CA
• OSTI ID: 6344757
• Journal Information: Acta Metall.; (United States), Journal Name: Acta Metall.; (United States) Vol. 26:5; ISSN AMETA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
BUBBLES
CAVITIES
COALESCENCE
CREEP
CRYSTAL STRUCTURE
DUCTILITY
ELEMENTS
EMBRITTLEMENT
FAILURES
FRACTURES
GRAIN BOUNDARIES
HYDROGEN COMPOUNDS
MECHANICAL PROPERTIES
METALS
MICROSTRUCTURE
OXYGEN COMPOUNDS
RUPTURES
SILVER
TEMPERATURE DEPENDENCE
TENSILE PROPERTIES
TRANSITION ELEMENTS
WATER