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Vapor pressure and critical point of rubidium

Description: The vapor pressure of rubidium was experimentally determined from 1400 deg F up to its critical temperature. An empirical equation of the form ln P = A + B/T + C ln T + DT/sup m/ fit the data well when m = --2. A critical pressure of 1942.9 plus or minus 3.5 psia (132.2 plus or minus 0.24 ata) was measured. The corresponding critical temperature, extrapolated from the pressure-- temperature curve, agrees with 3790.7 plus or minus 10 deg R (2106 plus or minus 5 deg K) of Chung and Bonilla, which was adopted. The technique employed was the pressure tube method developed earlier in this laboratory and used for determining the vapor pressure of cesium. This method messures the critical pressure directly, as well as the vapor pressure at lower temperatures. (3 tables) (auth)
Date: January 1, 1973
Creator: Bhise, V.S. & Bonilla, C.F.
Partner: UNT Libraries Government Documents Department

High temperature vapor pressure and the critical point of potassium

Description: The vapor pressure of potassium was experimentally determined from 2100 deg F up to-its critical temperature. An empirical equation of the form ln P = A + B/T + C ln T + DT/sup 1.5/ was found to best fit the data. A critical pressure of 2378.2 plus or minus 4.0 psia (161.79 plus or minus 0.27 ata) was measured. The corresponding critical temperature, extrapolated from the pressure-- temperature curve, is 4105.4 plus or minus 5 deg R (2280.8 plus or minus 3 deg K). The technique employed was tae pressure tube method developed earlier in this laboratory and used for determining the vapor pressure of rubidium and cesium. This method measures tae critical pressure directly, as well as the vapor pressure st lower temperatures. (4 tables, 6 figures, 26 references) (auth)
Date: January 1, 1973
Creator: Jerez, W.R.; Bhise, V.S.; Das Gupta, S. & Bonilla, C.F.
Partner: UNT Libraries Government Documents Department

Revision of high temperature and critical properties of cesium

Description: The high-temperature equilibrium vapor and liquid phase densities of cesium reported previously from a tilting capsule'' test were recalculated with the aid of generalized mathematical relations for the phase densities, instead of a rectilinear diameters line extrapolated irom lower temperatures. The critical density and temperature found are 0.420 g/cc and 3686.0 deg R, respectively. In addition, the earlier high-temperature vapor pressure data and critical pressure of cesium by the pressure tube'' method were checked with the improved equipment now available, obtaining close reverification. The critical pressure was obtained as 1701.3 psia and the critical temperature by this independent method as 3699.1 deg R. Using the average critical temperature of 3692.1 plus or minus 8 deg R, the critical compressibility factor of cesium is calculated as 0.2177. (6 tables, 4 figures) (auth)
Date: January 1, 1973
Creator: Das Gupta, S.; Bhise, V.; Stuteville, D.W.; Chung, J.W. & Bonilla, C.F.
Partner: UNT Libraries Government Documents Department

Cluster carburizing. Progress report, June 1, 1973--May 31, 1974

Description: Tantalum alloys containing 27 at.% Hf and 1 at.% C + O were age-hardened in a carbon-free environment as a standard for comparison with cluster-carburized alloys. After aging for one hour, the alloys showed two hardness peaks at 600 and 960 deg C. From a solutionized hardness of 350 VHN, the hardness increased to 700 VHN at the low-temperature peak and to 500 VHN at the high-temperature poak. A cellular reaction was observed to occur when annealing for one hour between 943 and 1078 deg C. An equation is given which predicts the volume fraction of cellular precipitate as a function of time and temperature. (6 figures) (DLC)
Date: January 1, 1974
Creator: Morral, J.E.
Partner: UNT Libraries Government Documents Department

High temperature vapor pressure and the critical point of potassium

Description: The vapor pressure was determined from 1600 deg F up to the critical point. The equation Ln P = A + B/T + C Ln T was found to fit the data well, a fourth term D/T/sup 2/ further improved the fit. A novel design was employed in measuring the vapor pressure, which provides a direct determination of the critical pressure, because at all tip temperatures higher than the critical temperature the same breakoff pressure'' is observed. This breakoff'' pressure'', which is produced when the liquid level reaches the critical temperature in its travel along the bore of the tube, is the critical pressure. (58 figures, 50 references) (DLC)
Date: January 1, 1972
Creator: Jerez, W.R. & Bonilla, C.F.
Partner: UNT Libraries Government Documents Department

Faceting of high angle grain boundaries in the coincidence lattice

Description: Faceting of high angle grain boundaries in SIGMA = 3 and SIGMA = 5 coincidence lattices of the fcc structure was studied using thinfilm bicrystal specimens of controlled geometry. A number of relatively high index boundaries in the coincidence lattices (containing relatively low planar densities of coincidence sites) was found to break up into low energy facets corresponding to low index planes of the coincidence lattices (containing high densities of coincidence lattice sites). These results are consistent with a general expectation that the grain boundary energy decreases as the planar density of coincidence sites increases, i.e., the two-dimensional periodicity of the boundary becomes shorter, and long-ranged distortions are reduced. (auth)
Date: November 16, 1973
Creator: Wagner, W.R.; Tan, T.Y. & Balluffi, R.W.
Partner: UNT Libraries Government Documents Department

Tensile properties of bare-rolled ingot-sheet beryllium from room temperature to 800$sup 0$C

Description: Tensile properties of bare-rolled ingot-sheet beryllium from room temperature to 800 deg C are reported. While strength values show a steady decrease above room temperature, tensile elongations exhibit peaks at approximately 300 and 700 deg C. The strainhardening exponent varies with temperature and amount of strain, and ranges between approximately 0.10 and 0.26. Metallographic examinations reveal cleavage fracture at the lower temperatures, accompanied by severe grain deformation above room temperature. This is followed by a temperature range in which ductile rupture occurs, and finally, at the higher temperatures, grainboundary failure. The low BeO content of this material and the post-rolling heat treatment given to the sheet are factors which improve the high-temperature ductility as compared to other grades of beryllium. (auth)
Date: December 13, 1973
Creator: Miley, D.V. & Brugger, R.P.
Partner: UNT Libraries Government Documents Department

X-ray photoemission studies of rare earth hard magnets

Description: From 19th conference on magnetism and magnetic materials; Boston, Massachusetts, USA (13 Nov 1973). An attempt was made to probe the electronic properties of the RCo/sub 5/ compounds by x-ray photoelectron spectroscopy studies of SmCo/sub 5/ and PrCo/sub 5/ and to relate the results to the properties o f the pure metals and to the picture developed to describe the magnetism of the compounds. Results indicate a valence band structure similar to that of Co metal; there is the suggestion that if there is charge flow it is off the rare-earth sites; there appears to be significant change in the 4f spectra from that of the pure rareearth metals; and there is a suggestion of f-- d hybridization. (auth)
Date: January 1, 1973
Creator: Cuthill, J.R.; McAlister, A.J.; Erickson, N.E. & Watson, R.E.
Partner: UNT Libraries Government Documents Department