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Creep cavitation in a nickel aluminide

Conference ·
OSTI ID:6923870
A nickel aluminide with the composition Ni-23.5, Al-0.5 Hf-0.2 B (at. %) has been creep-tested in tension at constant load (initial stress 250 MPa, temperature 1033K). The creep rate reaches a minimum at a strain of approximately 0.3%. Its increase at lalrlger strains is partly caused by grain boundary cavitation. Cavity size distributions corresponding to different creep times and strains were determined metallographically and evaluated in order to obtain the cavity growth rate as a function of cavity size. Contrary to a newly developed model for crack-like diffusive growth the cavity tip velocity increases with cavity size. This discrepancy is attributed to cavity coalescence. Sintering at elevated temperatures (1473K) reduces the diameter and increases the thickness of the disc-shaped cavities. Sintering of such cavities might be exploited to measure surface diffusivities.
Research Organization:
Oak Ridge National Lab., TN (USA); Universidad Nacional Autonoma de Mexico, Mexico City. Inst. de Fisica
DOE Contract Number:
AC05-84OR21400
OSTI ID:
6923870
Report Number(s):
CONF-861207-29; ON: DE87004276
Country of Publication:
United States
Language:
English

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