Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Hydrogen sorption isotherms have been measured between 542 and 798 deg C at pressures of 0.001 to 70 cm of Hg. The isotherms give the terminal solubility of S in the initial alloy phases and the limiting compositions of new phases containing H/sub 2/. Values for the heat of solution of H/sub 2/ at all concentrations are presented. A comparison of the data with that of the H-- Zr system indicates that, above a minimum H/sub 2/concentration, the alloy breaks down to give V and Zr. The alloy then behaves, to some extent, as the H--Zr system modified by the presence of U. X-ray diffraction studies give support to this interpretation (auth).
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The reaction of He with the epsilon phase of the 50 wt. % U--Zr alloy is studied using a sensitive vacuum microbalance apparatus to prepare the alloys, a sensitive McLeod gage to measure the dissociation pressures, and x-ray diffraction analyses to determine the phases present in the alloy. Although the reaction of H/sub 2/ with the alloy is very rapid at 100 deg C for oxide free surfaces, homogenization is very slow. Hydrogen alloys are prepared in the composition range of U/sub 0.28/Zr/sub 0.72/H/sub 0.0007/to U/sub 0.28/Zr/sub 0. 72/H/sub 0.121/ and the dissociation pressure measurements determined in the temperature range of 300 to 600 deg C. Due to the slow processes of homogenization, the hydride ZrH/sub 1.2/ is not readily precipitated below 400 deg C. On heating to 525 deg C and cooling, the hydride is readily formed for compositions of U/sub 0.28/Zr/sub0.72/H/sub 0.035/ and higher. For lower H/sub 2/ compositions, the hydride is not found in the x-ray diffraction patterns on heating these compositions to 525 deg C and cooling. It is suggested that small hydride nuclei are formed which are not observable by x-ray diffraction methods. Due to a slow rate of metallic diffusion, these nuclei cannot grow. The solubility of H/sub 2/ in the alloy is determined to be approximately 0.02 at.% at 500 deg C. This is a smaller value than that found for pure Zr. However, the heat of solution of hydride is +8,900 plus or minus 1,000 calories per gram atom and compares with a value of +8,600 calories per gram atom found for Zr. A transformation of the epsilon to gamma phase of the alloy is found near 550 deg C. (auth).
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Author: Stanley Kass
Author: Harold E. Bigony
Author: C. C. Gregg