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A calorimetric determination of the enthalpy of formation and a description of the defect structure of the ordered beta-phase /Ni, Cu/ /1-x/ Al/x/In order to describe thermodynamically the defect structure of an ordered B-Hume-Rothery phase, the heat of formation of (Ni,Cu)(1-x)Al(x) was measured at 1100 K as a function of concentration in the range x (sub Al) = 0.4 and 0.55 for three substitution rations x (sub Ni)/x (sub Cu) = infinity; 11; 5. The heat of formation of the NiAl beta-phase is strongly negative. For the stoichiometric composition it is -72.2 kJ/g-atom. On both the nickel-rich side and the aluminum-rich side the magnitude of the enthalpy of formation decreases linearly with concentration. Substitution of nickel for copper decreases the magnitude of the enthalpy of formation over the entire homogeneity range for the phase (Ni,Cu)(1-x)Al(x). The curve for the enthalpy of formation as well as the literature values for the chemical potential of aluminum are described with great accuracy by the disorder model of Wagner-Schottky.
Document ID
19880011050
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Henig, E. T.
(NASA Headquarters Washington, DC United States)
Lukas, H. L.
(NASA Headquarters Washington, DC United States)
Date Acquired
September 5, 2013
Publication Date
March 1, 1988
Subject Category
Metallic Materials
Report/Patent Number
NAS 1.77:20157
NASA-TT-20157
Accession Number
88N20434
Funding Number(s)
CONTRACT_GRANT: NASW-3047
Distribution Limits
Public
Copyright
Public Use Permitted.
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