Li overlayer formation, oxidation and sputtering characteristics of Al-Li alloys and W/Al-Li composites for fusion applications
- Argonne National Lab., IL (USA)
- Corium Industries, Inc., Atlanta, GA (USA)
The next generation of long pulse fusion devices will impose severe requirements on the properties of plasma-facing materials. In devices such as ITER, a divertor design is being considered, using a divertor plate which would be either tungsten or a low-Z material such as graphite or beryllium. Strongly segregating lithium alloys have been proposed as a means of producing a self-sustaining low-Z overlayer which lowers plasma Z{sub eff} and resists self-sputtering. Aluminum-lithium alloys are among the better-characterized lithium-bearing alloys, and it has been demonstrated that lithium segregates strongly in aluminum. However, aluminum has a relatively low melting point, and for low lithium concentrations, the lithium diffusion rate is too slow to replenish lithium at the rate at which it is eroded by the incoming plasma. It has been suggested previously that the superionic {beta} phase Al-Li alloy (48--54 at. % Li) should have high enough diffusivity to be able to replenish surface lithium, and that incorporation of the {beta}-phase AlLi in a composite with tungsten would provide high temperature strength and melt layer stability, along with significantly better thermal conductivity than pure tungsten. Such a composite has been fabricated, as well as a variation containing titanium as a means of controlling oxidation at grain boundaries. The Li overlayer formation, erosion, and replenishment are characterized for the {beta}-phase LiAl alloy, and W-AlLi and W-Ti-AlLi composites. It is found that if there is no oxide layer to inhibit the Li segregation, Li diffusion is extremely rapid, and an oxygen-free Li overlayer is formed which is stable under continuous ion beam sputtering. 21 refs., 7 figs.
- Research Organization:
- Argonne National Lab., IL (USA); Corium Industries, Inc., Atlanta, GA (USA)
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- W-31109-ENG-38; AC05-87ER80508
- OSTI ID:
- 6224143
- Report Number(s):
- ANL/CP-71722; CONF-901007-51; ON: DE91006529
- Resource Relation:
- Conference: 9. topical meeting on technology of fusion energy, Oak Brook, IL (USA), 7-11 Oct 1990
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
FABRICATION
LITHIUM ALLOYS
THERMONUCLEAR REACTOR MATERIALS
TITANIUM ALLOYS
TUNGSTEN ALLOYS
DIFFUSION
EROSION
GRAIN BOUNDARIES
INTERMETALLIC COMPOUNDS
SPUTTERING
ALLOYS
CRYSTAL STRUCTURE
MATERIALS
MICROSTRUCTURE
700209* - Fusion Power Plant Technology- Component Development & Materials Testing
360101 - Metals & Alloys- Preparation & Fabrication
360105 - Metals & Alloys- Corrosion & Erosion