Partial Thermodynamic Properties of gamma-(Ni,Pt)3Al in the Ni-Al-Pt System (Preprint)

摘要

A series of measurements were made to determine how Pt influences the partial thermodynamic properties of Al and Ni in gamma-(Ni,Pt)3Al and liquid in the Ni-Al-Pt system. The activities of Al and Ni were measured by the vapor pressure technique with a multiple effusion-cell vapor source coupled to a mass spectrometer (multi-cell KEMS). For a consistent XAl = 0.24, adding Pt, from XPt = 0.02 to 0.25, reduces alpha(Al) almost an order of magnitude, from about 2x10-4 to 2x10-5, at 1560K. This occurred with a consistent delta-mH(Al) of -203 +or- 10 kJmol-1 and the decrease in alpha(Al) was due to an increase in delta-mS(Al), from -60 to -40 Jmol-1K-1 with a decrease in the Ni/Pt ratio.