Counteracting effects of boron and hydrogen on ductility in Ni{sub 3}Al
Conference
·
OSTI ID:72528
- State Univ. of New York, Buffalo, NY (United States). Dept. of Mechanical and Aerospace Engineering
A minute amount of boron doping in polycrystalline Ni{sub 3}Al can suppress embrittle due to environmental moisture. However, B is ineffective in suppressing hydrogen embrittlement due to cathodic charging. A mechanism is proposed to explain this seemingly contradictory dichotomy. Grain boundaries in B-free Ni{sub 3}Al contain crack-like microcavities, to the tips of which atomic hydrogen, generated by the reaction of moisture with Al, can diffuse and cause embrittlement. In B-doped Ni{sub 3}Al interstitial B atoms interact with Ni atoms and reduce the strength of directional bonding between Ni and Al atoms, such that the atoms call relax easily to close up the microcavities. thereby reducing environmental embrittlement. In the presence of a large amount of hydrogen, introduced by cathodic charging, microcracks can be nucleated in B-doped Ni{sub 3}Al by hydrogen-enhanced dislocation activity, and then hydrogen embrittlement can proceed by enhanced plasticity at the crack tips.
- OSTI ID:
- 72528
- Report Number(s):
- CONF-941144--; ISBN 1-55899-265-0
- Country of Publication:
- United States
- Language:
- English
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