High-temperature phase diagram for the system Zr--O
Journal Article
·
· J. Am. Ceram. Soc.; (United States)
The melting, eutectic, peritectic, solidus, and liquidus temperatures in the system Zr--O were measured by an optical pyrometric technique requiring only a few hundred milligrams of sample. The saturation solubility of oxygen in ..cap alpha..-Zr(s) between 1270 and 1980/sup 0/C and the lower phase boundary of the ZrO/sub 2-x/ phase between 1900 and 2400/sup 0/C were measured by an isopiestic equilibration method. The oxygen solubility limit in ..cap alpha..-Zr(s) agrees with previous low-temperature studies and reaches a maximum solubility of 35 +- 1 at. % O at the eutectic temperature, 2065/sup 0/C +- 5/sup 0/C. The maximum melting temperature of ..cap alpha..-Zr(ss) is 2130/sup 0/ +- 10/sup 0/C and corresponds to a composition of 25 +- 1 at. % O. Both of these temperatures are approximately 150/sup 0/ higher than previously reported. Liquidus compositions above the eutectic temperature were obtained via mass spectrometry from the kinetic behavior of the liquid solution-ZrO/sub 2-x/(s) mixture as it approached equilibrium at 2125/sup 0/ +- 5/sup 0/C. The lower phase boundary or solidus of the ZrO/sub 2-x/ phase departs appreciably from ideal stoichiometry above 1900/sup 0/C and smoothly reaches its most reduced composition, 61 at. % (ZrO/sub 1/./sub 56/) near 2300/sup 0/C. The solidus is retrograde at higher temperatures. The melting temperature of the stoichiometric dioxide is 2710/sup 0/ +- 15/sup 0/C.
- Research Organization:
- Argonne National Lab., IL
- OSTI ID:
- 6516701
- Journal Information:
- J. Am. Ceram. Soc.; (United States), Journal Name: J. Am. Ceram. Soc.; (United States) Vol. 60:7-8; ISSN JACTA
- Country of Publication:
- United States
- Language:
- English
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