Incipient melting and oxidation of grain boundary in a two-phase Ni{sub 3}Al alloy containing Zr
- Associated Western Universities, Richland, WA (United States)
- State Univ. of New York, Buffalo, NY (United States). Dept. of Mechanical and Aerospace Engineering
Incipient melting and oxidation of grain boundaries at elevated temperatures have been investigated in the investment cast billet of a two-phase ({gamma} + {gamma}{prime}) nickel aluminide alloy (Ni{sub 74.48}Al{sub 16.98}Cr{sub 8.02}Zr{sub 0.51}B{sub 0.10}), designated as IC-218. Due to enrichment of Zr, which can form eutectic alloys with Ni, the inter-dendritic regions and grain boundaries melted incipiently at 1,150 C. During quenching the molten layers often opened up producing cracks at the boundaries. Annealing at 1200 C in air for 570 min produced elongated ZrO{sub 2} precipitates at the grain boundaries. There was Zr depletion inside the grains in the vicinity of the precipitates. Such precipitates were scarcely observed in the specimens annealed in air at 1,100 C for 23 h. Thus, the molten Ni-Zr alloy at the boundaries promoted internal oxidation.
- OSTI ID:
- 72507
- Report Number(s):
- CONF-941144--; ISBN 1-55899-265-0
- Country of Publication:
- United States
- Language:
- English
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