The vaporization thermodynamics of the aluminum-rich portion of the Hf-Al system have been investigated by Knudsen cell-mass spectrometry in the temperature range 1280-1680 K. The aluminum vapor pressures were measured in the two-phase regions in the composition range 50%-75% at. Al, and the enthalpy changes of the decomposition reactions were determined by second-law and third-law methods. Hence, the enthalpies of formation of the intermetallic compounds were derived: HfAl3, - 44.7 kJ g(-1) atom(-1); Hf2Al3, - 40.8 kJ g(-1) atom(-1). The results of the vaporization experiments which yielded a residue not assignable to a definite phase were tentatively submitted to thermodynamic analysis, by introducing the formation of HfAl or Hf5Al4, and their enthalpies of formation were derived.
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|Titolo:||THERMODYNAMIC STUDY OF INTERMETALLIC PHASES IN THE HF-AL SYSTEM|
|Data di pubblicazione:||1995|
|Appartiene alla tipologia:||01a Articolo in rivista|