Kinetics of cavity growth and creep fracture in silver containing implanted grain boundary cavities

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

DOI:https://doi.org/10.1016/0001-6160(78)90024-X· OSTI ID:6490635

Goods, S H; Nix, W D

An experimental technique was developed for implanting water vapor bubbles (H/sub 2/O/sub (v)/) of fixed size and spacing along the grain boundaries of polycrystalline silver. The effects of this microstructure on the creep fracture behavior have been studied by conducting constant stress creep tests over the temperature range 200 to 550/sup 0/C. The stress and temperature dependence of creep fracture has been determined for samples containing 1 ..mu..m diameter gas bubbles spaced 10 ..mu..m apart. The time to rupture varies with the applied stress as: t/sub r/ approx. sigma/sup -3/ /sup 7/. The activation energy for the creep fracture is found to be 85.5 kJ/mol, which is in close agreement with the activation energy for surface self diffusion. Scanning electron microscopy of the creep fracture surfaces indicates a brittle intergranular failure. The grain boundary facets on the fracture surface exhibit a dimpled structure. The spacing of these dimples corresponds to the initial gas bubble spacing, indicating that fracture occurs solely by the growth of the pre-existing gas bubbles. It is found that the stress, temperature and microstructural dependence of the rupture time, as well as the absolute rupture time itself, can be described accurately by a model of lenticular cavity growth and creep fracture proposed by Chuang and Rice. In this treatment, self diffusion along the cavity surface is the rate limiting step and the rupture time is predicted to vary as sigma/sup -3/, in close agreement with the experimental data.

• Research Organization: Stanford Univ., CA
• OSTI ID: 6490635
• Journal Information: Acta Metall.; (United States), Vol. 26:5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
SILVER
CREEP
MICROSTRUCTURE
BUBBLES
CAVITIES
CRYSTAL GROWTH
DIFFUSION
EMBRITTLEMENT
FRACTURES
GASES
GRAIN BOUNDARIES
RUPTURES
SIZE
SURFACES
WATER
CRYSTAL STRUCTURE
ELEMENTS
FAILURES
FLUIDS
HYDROGEN COMPOUNDS
MECHANICAL PROPERTIES
METALS
OXYGEN COMPOUNDS
TRANSITION ELEMENTS
360103* - Metals & Alloys- Mechanical Properties
360102 - Metals & Alloys- Structure & Phase Studies