Accession Number : AD0282433

Title :   THE THERMODYNAMIC PROPERTIES OF THE SYSTEMS NB-H, V-H AND TA-H

Corporate Author : ILLINOIS INST OF TECH CHICAGO

Personal Author(s) : VELECKIS,EWALD

Report Date : JAN 1960

Pagination or Media Count : 1

Abstract : The equilibrium pressure method was employed to determine the solubility of H in Group VB metals in the temperature range 250 to 650 C, and for H pressures extending up to one atmosphere. Only a single solid solution phase was found throughout the experimentally investigated regions. In all three systems, however, the shape of the low-temperature isotherms clearly indicated the existence of two-phase immiscibility intervals. For all conditions, H was more soluble in Nb than it is in Ta or V. The solubility in Ta is higher than in V except for higher compositions, where the reverse is true. The maximum H solubility limits are independent of temperature and correspond to the atomic ratio 0.89 for Nb and V and 0.71 for Ta. Partial phase diagams constructed for the three systems include the proposed boundaries of the heterogeneous two-phase region. The thermodynamic properties determined from the experimental data were in good agreement with those calclated from the statistical model.

Descriptors :   *HYDROGEN, *NIOBIUM, *SOLUTIONS(MIXTURES), *TANTALUM, *VANADIUM, ATOMS, CRYSTAL LATTICES, GASES, HIGH TEMPERATURE, PRESSURE, SOLIDS, SOLUBILITY, TABLES(DATA), THEORY, THERMODYNAMICS, TRANSITION METALS

Distribution Statement : APPROVED FOR PUBLIC RELEASE