Formation of water vapor bubbles in copper and their effect on intergranular creep fracture
Small, closely spaced water vapor bubbles are formed along grain boundaries in coarse grained copper by annealing first in air at 800/sup 0/C and then in hydrogen at 600/sup 0/C. Almost all of the cavities are formed at grain boundaries, primarily because oxygen strongly segregates to grain boundaries in copper. The average cavity diameter and planar spacing are found to be 0.8 and 3.2 ..mu..m, respectively. A study of the creep fracture properties of copper containing the above cavity microstructure indicates that intergranular cavity growth is controlled by the rate of self diffusion along the cavity surface in the manner first described by Chuang and Rice. The stress dependence of the rupture time is found to be of the form t/sub r/ approx. sigma/sup -3/. The temperature dependence for fracture is characterized by an activation energy of 92 kJ/mol, which is close to that for surface self diffusion. These properties, together with the absolute rupture times are in close agreement with the Chuang-Rice theory in the limit of surface diffusion control. The determination fo the controlling fracture mechanism is supported by metallographic and fractographic evidence.
- Research Organization:
- Stanford Univ., CA
- OSTI ID:
- 5348964
- Journal Information:
- Acta Metall.; (United States), Journal Name: Acta Metall.; (United States) Vol. 28:5; ISSN AMETA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360103* -- Metals & Alloys-- Mechanical Properties
ACTIVATION ENERGY
BUBBLES
CAVITIES
COPPER
CREEP
CRYSTAL STRUCTURE
ELEMENTS
ENERGY
FAILURES
FLUIDS
FRACTURE PROPERTIES
GASES
HYDROGEN COMPOUNDS
MECHANICAL PROPERTIES
METALS
MICROSTRUCTURE
OXYGEN COMPOUNDS
RUPTURES
TRANSITION ELEMENTS
VAPORS
WATER