An analysis of grain boundary sliding and grain boundary cavitation in discontinuously reinforced composites
- Ames Lab., IA (United States)
In this study, the creep cavitation and rupture characteristics of polycrystalline matrix material and discontinuously reinforced composites are investigated including grain boundary sliding behavior, reinforcement aspect ratio and interfacial behavior between the reinforcement and surrounding matrix grains. Free sliding of the grain boundaries, a continuous nucleation of the grain boundary cavities, their diffusional growth and coalescence to form grain boundary facet cracks are fully accounted for in the analyses. The results indicate that, with sliding grain boundaries, the stress enhancement factor for the composites is much higher than the one observed for the matrix material and its value increases with increasing reinforcement aspect ratio, reduction in the matrix grain size and sliding interfacial behavior between the reinforcement and the matrix. For the composites, the influence of grain boundary sliding on the creep life is reduced by the stress concentration effect that is seen at the end of the reinforcements. In contrast with the behavior of polycrystalline matrix material in composites after the formation of the first facet crack, resulting from the coalescence of the cavities, a significant time is required for the formation of the other grain boundary facet cracks across the ligament to cause final rupture. The results also show that experimentally observed higher creep exponents or stress dependent creep exponent values in discontinuously reinforced composites can occur as a result of creep damage evolution behavior.
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 247940
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 5 Vol. 44; ISSN XZ504Y; ISSN 1359-6454
- Country of Publication:
- United States
- Language:
- English
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