THERMODYNAMICS AND AMORPHIZATION OF THE NICKEL–LANTHANUM ALLOYS

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.

Keywords:

• Amorphization
• Ni–La alloys
• Phase diagram
• Thermodynamic properties

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, 1991.

^b Dischinger and Schaller, 2000.

^c Zhang et al., 1991.

^d Ivanchenko et al., 1982.

^e Buschow and Mal, 1972.

^f Data for reaction L + Ni₅La ↔ β-Ni₇La₂ are listed. Existence of Ni₁₇La₄ phase was not discovered.

^g Ni₁₆La₇ phase is characterized by Ni₂La (Ni_2.286La (Zhang et al., 1991)) composition, Ni₃La₂ phase by Ni_1.51La (Zhang et al., 1991), Ni₇La₅ (Ivanchenko et al., 1982), and Ni_xLa (x ∼ 1.4) (Buschow and Mal, 1972).

^h Data for reaction L ↔ NiLa + NiLa₃ are listed. Existence of Ni₃La₇ phase was not discovered.