Materials Transactions, JIM
Online ISSN : 2432-471X
Print ISSN : 0916-1821
ISSN-L : 0916-1821
Calculations of Mixing Enthalpy and Mismatch Entropy for Ternary Amorphous Alloys
Akira TakeuchiAkihisa Inoue
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2000 Volume 41 Issue 11 Pages 1372-1378

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Abstract

Chemical mixing enthalpy (ΔHchem) and mismatch entropy normalized by Boltzmann constant (SσkB) corresponding to the three empirical rules for the achievement of high amorphous-forming ability (AFA) were calculated with thermodynamical functions for the gross number of 6450 alloys in 351 ternary amorphous systems. The ternary amorphous alloys have ΔHchem of −86 to 25 kJ/mol and SσkB of 1.0×10−3 to 5.7. The average values of ΔHchem and SσkB are calculated to be −33 kJ/mol and 0.33, respectively. The 30 alloys in 9 ternary amorphous systems including 10 alloys in Ag–Cu–Fe system have positive values of ΔHchem. Most of the ternary amorphous alloys have the values of ΔHchem and SσkB inside a trapezoid region in ΔHchem−log(SσkB) chart except mainly for the H- and the C-containing alloys, Si–W–Zr system and the 32 alloys having positive values of ΔHchem. The analysis of AFA was carried out for typical five ternary amorphous systems. The following four results are derived. 1) Al–La–Ni and B–Fe–Zr alloys have high AFA in accordance with the concept of the three empirical rules. 2) The further multiplication of alloy components causes an increase in the AFA of Al–B–Fe alloys. 3) Thermodynamical factors represented by melting temperature and viscosity at the melting temperature are required for evaluation of AFA for Mg- and Pd-based amorphous alloys. 4) A tendency for log(SσkB) to increase with decreasing ΔHchem is recognized in each alloys system, implying the stabilization of an amorphous phase against solid solution and intermediate phase.

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