Elastic constants of thorium single crystals

Values for the elastic constants c11 , c12 and c44 of thorium were determined over the temperature range from 80 to 370 degrees K. by ultrasonic measurements on single crystals. Two crystals were prepared by the strain anneal method. One crystal was cut in the form of a circular plate about 0.7 inch in diameter and 0.06 inch thick. The [111] direction of the crystal was perpendicular to the sample face. Measurements on this crystal with a resonance technique produced values for the stiffness coefficient in the [111] direction. This stiffness coefficient is a function of all three elastic constants

Vanadium-chromium alloy system

On the basis of data obtaiined from melting point determinations, microscopic examination, and x-ray investigations, a phase I diagram is proposed for the V -Cr alloy system. The system forms a complete series of solid solutions with a minimum occurring in the solidus at 1750°C and approximately 70 w/o Cr. No intermediate phases were found in this system. Hardness and corrosion data are presented as a function of alloying composition

Ab initio calculation of the electromagnetic and neutral-weak response functions of 4He and 12C

Precise measurement of neutrino oscillations, and hence the determination of their masses demands a quantitative understanding of neutrino-nucleus interactions. To this aim, two-body meson-exchange currents have to be accounted for along within realistic models of nuclear dynamics. We summarize our progresses towards the construction of a consistent framework, based on quantum Monte Carlo methods and on the spectral function approach, that can be exploited to accurately describe neutrino interactions with atomic nuclei over the broad kinematical region covered by neutrino experiments.Comment: 8 pages, 4 figure, Proceedings of the 21st International Conference on Few-Body Problems in Physics, Chicago, Illinois, US

Engineering Solutions to Recycling Problems

There are a large number of serious environmental problems that have received an increasing amount of attention in recent years. Most of them are by-products of our complex technological society and stem directly from our rising standard of living and unprecedented population growth. Their solutions are equally complex and will require a combination of scientific understanding, engineering ingenuity, economic sagacity and political courage. It would be impossible to cover all of these problems in a short time. Therefore, consistent with my interest in process metallurgy, these remarks are limited to the optimization of our dwindling mineral resources with emphasis on the recycling and reuse of scrap metals

Tensile properties of yttrium-titanium and yttrium-zirconium alloys

Complete series of yttrium-titanium and yttrium-zirconium alloys were tested in tension at room temperature, and ultimate tensile strength, yield strength and reduction in area data are reported for these alloys. Yield point phenomena were encountered in both of these alloy systems

A study of the high-temperature air oxidation of yttrium metal

A survey was made of the high-temperature oxidation of yttrium metal and its effect on hardness. Corrosion of the metal was very slow at 450°C, but increased rapidly with temperature, becoming very severe at 925°C. Oxidation was found to increase the hardness of yttrium metal due to the diffusion of oxygen into the metal lattice

Preparation of yttrium metal by reduction of yttrium trifluoride with calcium

The preparation of yttrium metal by the reduction of yttrium trifluoride with calcium is described. Alternate methods employing the formation of a low melting Y-Zn or Y-Mg intermediate alloy are evaluated and data on chemical and microscopic purity of the resulting metal are presented

Aluminum-vanadium system

The nature of the aluminum-vanadium system has been reported on the basis of thermal, microscopic, chemical and X-ray evidence. The system contains six different solid phases at ambient temperatures: the four intermediate phase being peritectic in nature. Phase properties are summarized in Table 1

A process for purifying yttrium metal

A process is described for purifying crude or scrap yttrium metal by first reacting the yttrium with fused MgC12and then purifying the magnesium and YC13 products by co-distillation. Dissolution and purification are carried out in a single heating step. The purified YC1 3is reduced with calcium in the presence of the magnesium to form a Y -Mg intermediate alloy which is processed to yttrium sponge. Further refinement of the metal was obtained employing a salt extraction step and electron beam melting. Yttrium of 99. 9+% purity was obtained from metal of 99. 3% purity

Leading-Log Effects in the Resonance Electroweak Form Factors

We study log corrections to inelastic scattering at high Bjorken x for Q^2 from 1 to 21 GeV^2. At issue is the presence of log corrections, which can be absent if high x scattering has damped gluon radiation. We find logarithmic correction of the scaling curve extrapolated to low Q^2 improves the duality between it and the resonance plus background data in the Delta region, indicating log corrections exist in the data. However, at W > 2 GeV and high x, the data shows a (1-x)^3 form. Log corrections in one situation but not in another can be reconciled by a W- or Q^2- dependent higher twist correction.Comment: 13 pages, report nos. RPI-94-N90 and WM-94-106, revtex, two figures (available by fax or post