Actions for Formation of gamma(sup prime)-Ni3Al via the Peritectoid Reaction : gamma + beta (+ Al2O3)=gamma(sup prime)(+ Al2O3).

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Formation of gamma(sup prime)-Ni3Al via the Peritectoid Reaction : gamma + beta (+ Al2O3)=gamma(sup prime)(+ Al2O3).

Author
Copeland, Evan
Published
September 14, 2008.
Physical Description
1 electronic document
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Summary
The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8-32 at.%Al and temperature range T=1400-1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma(sup prime)-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3)=gamma + Beta(+ Al2O3), at 1640 +/- 1 K and a liquid composition of 24.8 +/- 0.2 at.%al (at an unknown oxygen content). The {gamma + Beta (+Al2O3} phase field is stable over the temperature range 1633-1640 K, and gamma(sup prime)-Ni3Al forms via the peritectoid, gamma + Beta (+ Al2O3)=gamma(sup prime) (+ Al2O3), at 1633 +/- 1 K. This behavior is consistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady-state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma(sup prime)-Ni2Al phase field.
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Collection
NASA Technical Reports Server (NTRS) Collection.
Note
Document ID: 20080047352.
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Copyright, Distribution as joint owner in the copyright.
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