High-temperature internal oxidation of Ag/1.2at.% Mg and Ag/0.25at.% Mg-0.25at.% Ni.
High-temperature oxygen diffusion and internal oxidation in Ag, Ag/1.2 at.% Mg (Ag-Mg), and Ag/0.25 at.% Mg-0.25 at.% Ni (Ag-Mg-Ni) have been studied, mostly in air and 8% O{sub 2}, at 450-835 C. The focus of the studies was on thermogravimetric analysis, microhardness tests, and optical and electron microscopy observations of grain growth and its inhibition by oxidation. The internal oxidation of both alloys exhibited nearly identical activation energies (0.81 eV for Ag-Mg and 0.83 eV for Ag-Mg-Ni) and rate constants. The maximum O content of both alloys was superstoichiometric (e.g., O/Mg > 1.0) and the maximum O/Mg ratios were higher at lower temperatures than at higher temperatures (e.g., 1.25 at 500 C and 1.05 at 800 C). Diffusion of O in pure Ag was {approx}60 times faster at 825 C and {approx}400 times faster at 500 C than internal oxidation of either of the Ag alloys. Grain growth of both alloys and of the Ag was quantified between 450-800 C and related to internal oxidation.
- Research Organization:
- Argonne National Lab., IL (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 11845
- Report Number(s):
- ANL/ET/CP-99215; TRN: AH200118%%300
- Resource Relation:
- Conference: 196th Meeting of the Electrochemical Society, Honolulu, HI (US), 10/17/1999--10/22/1999; Other Information: PBD: 8 Sep 1999
- Country of Publication:
- United States
- Language:
- English
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