Frank A. Kanda

The Determination of the Liquid Immiscibility Boundaries of the Lithium-Sodium and Thallium-Selenium Systems by the Liquid Density Method

Abstract The immiscibility boundaries and monotectic temperatures of the lithium-sodium and thallium-selenium systems were determined by techniques using density-temperature and density-composition isotherms. The immiscibility boundary of the lithium-sodium system was found to extend from 10.5 to 96 weight percent sodium at the monotectic temperature, 170°±1°C. The critical solution (consolute) temperature was found to be 306°±1°C. The thallium-rich immiscibility region of the thallium-selenium system has a consolute temperature of 750°±1°C and a monotectic isothermal of 380°±1°C extending over the composition range 0.1–32.9 atom percent selenium. The second immiscibility region in this system was found to have a consolute temperature of 454° ± 1°C and a monotectic isothermal of 201° ± 1°C. The latter extends between the composition limits 77–99.9 atom percent selenium.

The Absolute Viscosity of Some Lead-Tin Alloys

Abstract The absolute viscosity of lead, tin and nine of their alloys were measured as a function of temperature between the liquidus and 500°C by an oscillating cup viscometer. The viscosity of pure tin ranged from 0.01780 poise at 235°C to 0.01196 poise at 458°C. The viscosity of pure lead ranged from 0.02578 poise at 334°C to 0.01896 poise at 472°C. Viscosity isotherms, as a function of composition, showed an ideal linear behavior with no anomaly detected at the eutectic composition (26.1 at % Pb). A plot of log φ versus 1/T was linear for all samples. Accuracy of the data is estimated to be about 1%.

Refined crystal structure of Sr2Mg17 and Ba2Mg17

Abstract The crystal structures of Sr2Mg17 and Ba2Mg17 have been investigated and refined by single crystal counting diffractometer techniques. Sr2Mg17 crystallizes in space group P6 3 mmc with two formulas per unit cell having the dimensions: a o = 10.535 A ± 0.005 and c o = 10.356 A ± 0.005 . Ba2Mg17 crystallizes in the space group R 3 m with three formulas per unit cell having the dimensions: a o = 10.650 A ± 0.002 and c o = 15.587 A ± 0.002 . Atomic positions were determined using Patterson and Fourier maps coupled with least square refinement. The structures are related to the hexagonal CaZn5 lattice, obtained by: 3 × XMg5 = X3Mg15 in which a bonded pair of Mg atoms substitute for one heavy X atom giving X2Mg17. The structures differ in the pattern of substitution of the Mg pair for the heavy X atom. In both structures the pair of Mg atoms display an unusually close bond length of 3.02 A. Occupancy factors were allowed to vary for the Sr2Mg17 structure and the effect on the R factor disproved the suggestion of disorder in this structure.

The absolute viscosity of some lead-thallium alloys

Abstract The absolute viscosities of lead, thallium and seven lead-thallium alloys were measured as a function of temperature between the liquidus and 500 °C by an oscillating cup viscometer. The viscosity of pure lead ranged from 2.523 cP at 328.5 °C to 1.833 cP at 500.5 °C. The viscosity of pure thallium ranged from 2.600 cP at 303.5 °C to 1.708 cP at 500 °C. A plot of log η versus 1 T(K) was linear for all the samples studied. Isotherms of viscosity versus composition showed a broad maximum in the viscosity in the vicinity of the composition of maximum liquidus temperature (37.5 at.% Pb). The maximum appears to shift towards the equiatomic composition at higher temperatures where it becomes more diffuse. These results support the belief that certain liquid alloy solutions contain molecular-type aggregates or “clusters”, the stoichiometries of which are subject to a temperature-dependent dissociation reaction. Furthermore, the results support some previous reports that the composition range 12.5 – 100 at.% Pb is not a continuous primary solid solution, but may be interrupted by an intermediate phase or phases.

The Use of Liquid Densities as a New Technique for Determining Liquid Immiscibility Phase Boundaries

Abstract Liquid densities can be used to determine the immiscibility phase boundaries of any liquid systems which display these regions, including alloys. The densities are determined by the Archimedean method. Using an automatic recording balance, dynamic density measurements can be made as a function of temperature. Inflections in the curves occur at the onset of immiscibility. Density-composition isotherms can also delineate these phase boundaries where they intersect the density curve (slope zero) of the appropriate liquid layer. The methods are applied to the isomyl alcohol-glycerol and phenol-water systems. Results are compared to other methods of determining the boundaries. The limitations and accuracies of these techniques and equipment are described.