Comments on the internal stress model of Harper-Dorn creep

Journal Article · Mon Nov 15 04:00:00 EST 1993 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(93)90121-8· OSTI ID:6006896

Wang, J N ^[1]

---

1. Monash Univ., Clayton (Australia). Dept. of Earth Sciences

At intermediate to high temperatures single and polycrystalline metals, alloys, ceramics and minerals often deform by the diffusion-controlled dislocation mechanism of power law creep at high stresses, but of Harper-Dorn (H-D) creep at low stresses. H-D creep is characterized by a stress exponent n of unity and an activation energy - equal to that for power law creep and creep rates that are insensitive to grain size. Recently, a model was proposed to explain H-D creep, based on the assumption of the presence of an internal stress [sigma][sub i], which arises from the random dislocation density [rho] within subgrains. This internal stress model has been used to predict the H-D creep behavior in pure metals, alloys, ceramics and NaCl. It is the intent of this communication to show that this model only provides an approach to unify the low stress (n = 1) and high stress (n = 5) data, but reveals no information about the Newtonian viscous flow mechanism at low stresses, H-D creep or diffusional creep.

• OSTI ID: 6006896
• Journal Information: Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 29:10; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALKALI METAL COMPOUNDS
ALLOYS
CERAMICS
CHLORIDES
CHLORINE COMPOUNDS
CREEP
DEFORMATION
ELEMENTS
HALIDES
HALOGEN COMPOUNDS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
METALS
SODIUM CHLORIDES
SODIUM COMPOUNDS
STRESSES