Accession Number : AD0487194

Title :   DEVELOPMENT AND APPLICATION OF METHODS FOR PREDICTING THE TEMPERATURE COMPOSITION STABILITY OF REFRACTORY COMPOUNDS.

Descriptive Note : Technical rept. 15 Feb 65-30 Apr 66,

Corporate Author : MANLABS INC CAMBRIDGE MA

Personal Author(s) : Bernstein, Harold

Report Date : JUN 1966

Pagination or Media Count : 157

Abstract : The object of this investigation was the prediction of high temperature phase equilibria in binary systems through the analystical treatment of the temperature-composition stability of thermodynamic phase models. Interstitial compound phases were treated as special cases of the Schottky-Wagner model of defect solids in which departure from stoichiometr are accounted for by lattice vacancies. Disorder solution phases, both liquid and solid were treated by the regular solution model. The resulting analysis provides explicit equations from which equilibrium phase limits, vapor pressures and Langmuir vaporization rates can be calculated once the characteristic parameters introduced by the models are specified. Eutenctice and peritectic melting points are predictable from the crossing of calculated phase limit curves. The problem of the vaporization kinetics and the time varying composition dependence of compound and solution phases under Langmuir vaporization conditions is discussed and equations developed for calculating the instantaneous composition, weight and vaporization rate of a Langmuir specimen. The analytical properties of ternary compound and solution phases is formulated as an extension of the binary models. (Author)

Descriptors :   (*PHASE STUDIES, THERMODYNAMICS), CARBIDES, BORIDES, MATHEMATICAL PREDICTION, MELTING, HIGH TEMPERATURE, EQUATIONS OF STATE, VAPOR PRESSURE, VAPORIZATION, DIFFERENTIAL EQUATIONS, TITANIUM ALLOYS, ZIRCONIUM ALLOYS, HAFNIUM ALLOYS, NIOBIUM ALLOYS, TANTALUM ALLOYS, REFRACTORY METALS.

Subject Categories : Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE