Evolution of internal stresses and substructure during creep at intermediate temperatures

Journal Article · Sun Apr 01 04:00:00 EST 1984 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(84)90066-X· OSTI ID:6106665

Morris, M A; Martin, J L

Secondary creep has most generally been associated with a rather steady structure. Many models have been suggested to explain the constant strain rate in terms of the effective stress which is determined by the structurally-dependent internal stresses. The internal stresses deduced macroscopically have been of the order of half the applied stress. In this article, by pinning the dislocations under load in an Al-Zn alloy, the evolution of the structure and local effective stresses with strain has been identified by electron microscopy. Values of local effective stresses at the subgrain boundaries ranging between 10-20 times the applied stress have been measured. The emission of dislocations from these boundaries and the evolution of substructure within the subgrain interior indicate that the controlling mechanism during the creep process is the relaxation of internal stresses by this emission. At the same time, the subboundary stress fields existing in different subgrains determine their different behaviour as a function of time. Hard and soft subgrains alternate in the deformation process to produce overall uniform strain.

• Research Organization: Institut de Genie Atomique. Ecole Polytechnique Federale de Lausanne, Lausanne
• OSTI ID: 6106665
• Journal Information: Acta Metall.; (United States), Journal Name: Acta Metall.; (United States) Vol. 32:4; 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
ALLOY SYSTEMS
ALLOYS
ALUMINIUM ALLOYS
BINARY ALLOY SYSTEMS
CREEP
CRYSTAL MODELS
DISLOCATION PINNING
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
STRAIN RATE
STRESSES
TEMPERATURE EFFECTS
TEMPERATURE GRADIENTS
ZINC ALLOYS