- Conference date: 3-6 Feb 2002
- Location: Albuquerque, New Mexico (USA)
Arc melted Mo-41%Re has been produced at the Oak Ridge National Laboratory using a manufacturing process that is similar to that used for the production of iridium alloys for the encapsulation of plutonium oxide in the General Purpose Heat Source. This particular alloy of molybdenum and rhenium was selected because it would have about the lowest thermal conductivity while avoiding a composition where processing and use could lead to precipitation of undesirable phases. The Mo-41%Re was rolled into plate and sheet products which were used for characterization and to supply material for research and development relevant to alkali metal thermal to electric conversion (AMTEC) cells. Initial attempts indicated that the arc melted Mo-41%Re is fabricable in similar shapes and geometries required for the AMTEC cell. In addition, it was demonstrated that arc melted Mo-41%Re can be electron beam welded without the porosity normally observed in welded powder metallurgy products. Preliminary assessments of the properties of Mo-41%Re were made to provide recommended data for design purposes. In some cases, the only available data were obtained on powder metallurgy or wrought material or on material with different percentages of rhenium. Experimental data indicate that the electrical resistivity and thermal conductivity of Mo-41%Re are about the same as those of Nb-1Zr, which was the refractory alloy initially considered for this application. The ultimate and yield strengths are substantially greater than those of Nb-1Zr. The oxidation resistance of Mo-41%Re is much better than that of Nb-1Zr for two reasons. Firstly, the oxidation rate is slower for the Mo-41%Re and, secondly, oxidation that does occur is limited to a surface effect and does not reduce the strength and ductility as is observed with Nb-1Zr. Oxidation of Mo-41%Re does cause thinning, and preliminary values of the thinning rates at 800 and 900 °C in a rather high partial pressure of oxygen are provided. This factor needs to be considered in planning production, storage, and ground testing.
- Surface oxidation
- Electrical resistivity
- Powder metallurgy
- Thermal conductivity
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