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Journal of Materials Science

, Volume 27, Issue 16, pp 4501–4510 | Cite as

Observations on the crack-enhanced creep-fracture of a polycrystalline alumina with a glassy grain-boundary phase

  • K. Y. Donaldson
  • A. Venkateswaran
  • D. P. H. Hasselman
Papers

Abstract

An experimental study was conducted of the role of cracks in the creep-rupture behaviour of a polycrystalline alumina with glassy grain-boundary phase at stress regimes and temperatures at which failure is anticipated to occur from pre-existing flaws. Samples were tested without and with artificial flaws in the form of slots or indentation cracks. All three sample types exhibited non-linear creep. The relative rate of increase in creep rate with increasing dimension of slot-depth greatly exceeded the corresponding increase in specimen compliance, as expected for non-linear creep. An analysis of the data indicated that the observed creep behaviour was primarily controlled by crack-enhanced creep with a minor contribution from elastic creep by crack growth. Very poor correlations were found for the stress dependence of the creep rate and time-to-failure. In terms of Monkman-Grant behaviour, good correlations existed between creep rate and time-to-failure, independent of stress and size of the slots or indentation cracks. Because failure originated from pre-existing flaws, the experimental findings of this study suggest the existence of a failure mechanism referred to by the present authors as “crack-enhanced creep fracture”.

Keywords

Failure Mechanism Creep Rate Relative Rate Sample Type Creep Behaviour 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1992

Authors and Affiliations

  • K. Y. Donaldson
    • 1
  • A. Venkateswaran
    • 1
  • D. P. H. Hasselman
    • 1
  1. 1.Department of Materials EngineeringVirginia Polytechnic Institute and State UniversityBlacksburgUSA

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