A small dc arc melter was designed and constructed to run bench-scale investigations on various aspects of development for high-temperature (1,500-1,800°C) proccssing of simulatcd transuranic-contaminatcd waste and soil located at the Radioactive Waste Management Complex (RWMC). Several recent system design and treatment studies have shown that high-tempcrature melting is the preferred treatment. The small arc melter is needed to establish techniques and procedures (with surrogates) prior to using a similar melter with the transuranic-contaminatcd wastes in appropriate facilities at the site. This report documents the dcsign and construction, starting and heating procedures, and tests evaluating the mclter's ability to process several waste types stored at the RWMC. lt is found that a thin graphite strip provides reliable starting with initial high current capability for partially melting the soil/waste mixture. The heating procedure includes (1) the initial high current-low voltage mode, (2) a low current-high voltage mode that " commences after some slag has tbrmed and arcing dominates ovcr the receding graphite conduction path, and (3) a predominantly Joule heating mode during which thc currcnt can bc increased within the limits to maintain relatively quiescent operation. Scvcral experiments involving the melting of simulated wastes arc discussed. Energy balancc, slag tcmpcraturc, and electrode wear mcasurements are presented. Recommendations for further refinements to enhance its processing capabilities are identified. Future studies anticipated with the arc melter include waste form processing development; dissolution, retention, volatilization, and collection for transuranic and low-levcl radionuclides, as well as high vapor prcssure metals; clcctrode material development to minimize corrosion and erosion; refractory corrosion and/or skull formation effects; crucible or melter geometry; metal oxidation; and desirable melt reduction/oxidation (redox) conditions.

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This report describes a simple automated system for measuring interfacial tension using the pendant or sessile drop method. The size and shape of a transparent or opaque drop of one fluid immersed in a second, transparent, fluid is recorded with a CCD video camera and digitized and stored by a computer-controlled system. Custom software determines various droplet shape factors and computes the interfacial tension. A limited number of video frames can be stored on disc, or longer runs can be stored on video tape for later digitization. Alternately, only the shape factor and interfacial tension data are stored to reduce demands on the storage medium.

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This report describes the INEL Research Center (IRC) arc melter facility and its recent modifications. The arc melter can now be used to study volatilization of toxic and high vapor ' pressure metals and the effects of reducing and oxidizing (redox) states in the melt. The modifications include adding an auger feeder, a gas flow control and monitoring system, an offgas sampling and exhaust system, and a baghouse filter system, as well as improving the electrode drive, slag sampling system, temperature measurement and video monitoring and recording methods, and oxidation lance.

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Pure copper and Alloy 5083 aluminum were processed by equal channel angular extrusion (ECAE); their microstructural evolution and corresponding mechanical properties were investigated. Work also began on the possible use of ECAE to synthesize advanced materials or to consolidate metal powders or powder mixtures.The die tooling used for ECAE is described and selected microstructural and mechanical property results for ECAE-processed copper and cold-rolled (conventionally-processed) copper in the as-processed and annealed condition are compared. Results thus far show that the "pure" metal is prone to low temperature recrystallization after large strain hardening-more beneficial effects are expected in the dispersion-strengthened and precipitation-hardening alloys. The large range of tensile properties and grain sizes from the copper allowed a flow stress analysis to be performed. From this analysis, a new model for flow stress behavior is proposed.An evaluation of ECAE processing of material for spot welding electrodes began. Results to date include electrodes of ECAE-processed commercially pure copper (Alloy 101). Future work involving Glidcop® (Al 2 O 3 oxide dispersionstrengthened copper) and CuCrZr (Cr-Zr precipitation dispersion) materials will be required to fully investigate the benefits of ECAE for electrode life extension.Initial work on Aluminum Alloy 5083 showed that ECAE led to grain refinement as well as broke up and more uniformly dispersed the hardening precipitates. This is desirable for enhancing superplastic behavior.Study of ECAE for consolidating metal powder began. Early results with a Cu-Ag powder indicate that near 100% density was achieved with roomtemperature consolidation. iv SUMMARYThis program is evaluating the potential of a novel metals processing technique called equal channel angular extrusion (ECAE) for developing advanced industrial materials for the transportation industry. The program is a collaborative effort among three national laboratories, the Idaho National Engineering and Environmental Laboratory (INEEL), Pacific Northwest National Laboratory (PNNL), and Los Alamos National Laboratory (LANL). The program began in March 1998; this report describes progress through May 1999.INEEL is performing ECAE on a variety of materials and investigating their microstructural evolution and mechanical properties. Pure copper was chosen for the initial stage of the investigation because the extensive data on the microstructure and properties of copper in the literature allow a thorough comparative study of ECAE vs. conventional processing. Also, dispersionstrengthened copper alloys are widely used in industry. In particular, these alloys are used in the transportation industry for manufacturing spot welding electrodes. Evaluation of ECAE of copper and its alloys could, therefore, lead to developing improved materials for important industrial applications.PNNL is investigating the effect of ECAE on the grain size of aluminum Alloy 5083. It is hypothesized that ECAE will refine the ...