Abstract
The thermodynamic properties of liquid and crystalline Ni–La alloys were studied over the whole range of compositions and a wide temperature range, 685–1854 K, by Knudsen mass spectrometry and an integral variant of the effusion method realized under ultrahigh oilless vacuum. Complete and reliable thermodynamic description of all intermediate phases in the Ni–La system was obtained. The thermodynamic functions of the melts were described by the associated solution model. The existence of the complexes NiLa and Ni2La in the melts was found. The contributions of various intercomponent chemical interaction types (covalent and metallic) to thermodynamic functions were estimated. The present results were applied to computation of the phase diagram. Obtained thermodynamic description of the Ni–La alloys allowed the analysis of their transformation into amorphous state. It was determined that the magnitude of the associate formation entropy should be used for quantitative concept development of the propensity of metallic melts to amorphization.
Acknowledgment
This work was supported by the Russian Foundation for Basic Research (projects no. 05-02-17573).
Notes
a Number of measured points.
a Okamoto, Citation1991.
b Dischinger and Schaller, Citation2000.
c Zhang et al., Citation1991.
d Ivanchenko et al., Citation1982.
e Buschow and Mal, Citation1972.
f Data for reaction L + Ni5La ↔ β-Ni7La2 are listed. Existence of Ni17La4 phase was not discovered.
g Ni16La7 phase is characterized by Ni2La (Ni2.286La (Zhang et al., Citation1991)) composition, Ni3La2 phase by Ni1.51La (Zhang et al., Citation1991), Ni7La5 (Ivanchenko et al., Citation1982), and NixLa (x ∼ 1.4) (Buschow and Mal, Citation1972).
h Data for reaction L ↔ NiLa + NiLa3 are listed. Existence of Ni3La7 phase was not discovered.