Creep cavitation in a nickel aluminide
Intergranular cavities formed during creep of a nickel aluminide (Ni-23.5 Al-0.5 Hf-0.2 B, at. %) have been studied as a function of creep time and strain. Cavity growth rates as a function of cavity size have been evaluated from metallographically determined size distributions. The observed growth rates and cavity thicknesses are in order of magnitude agreement with a model of creep-enhanced crack-like diffusive growth, which we have developed recently. However, whereas our model predicts that the growth rate decreases with increasing cavity diameter, the opposite trend is observed experimentally. It is likely that coalescence is responsible for this discrepancy. Cavity growth in the investigated nickel aluminide also exhibits a grain size dependence. Cavities in large-grained (approx.210 ..mu..m) material were observed to grow slower than those in fine-grained (approx.50 ..mu..m) material. This result is explained by the comparatively low creep rate of the large-grained material. 10 figs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6816129
- Report Number(s):
- CONF-870447-2; ON: DE87004392
- Country of Publication:
- United States
- Language:
- English
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