Estimation of Enthalpy of Formation of Liquid Transition Metal Alloys: A Modified Prescription Based on Macroscopic Atom Model of Cohesion

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 47; no. 9; pp. 4741 - 4759
• Main Authors: Raju, Subramanian, Saibaba, Saroja
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.09.2016; Springer Nature B.V
• Subjects: Alloys; Bonding; Characterization and Evaluation of Materials; Charge density; Chemistry and Materials Science; Cohesion; Compressibility; Electron density; Electronegativity; Enthalpy; Formations; Liquid alloys; Liquid transition metals; Materials Science; Mathematical models; Metallic Materials; Molar volume; Nanotechnology; Parameter estimation; Parameter identification; Structural Materials; Surface tension; Surfaces and Interfaces; Thin Films; Transition metal alloys; Transition metals; Molar Volume; Bulk Modulus; Nontransition Metal; Liquid Alloy; Transition Metal Alloy
• DOI: 10.1007/s11661-016-3620-6
• ISSN: 1073-5623

The enthalpy of formation Δ o H f is an important thermodynamic quantity, which sheds significant light on fundamental cohesive and structural characteristics of an alloy. However, being a difficult one to determine accurately through experiments, simple estimation procedures are often desirable. In the present study, a modified prescription for estimating Δ o H f L of liquid transition metal alloys is outlined, based on the Macroscopic Atom Model of cohesion. This prescription relies on self-consistent estimation of liquid-specific model parameters, namely electronegativity ( ϕ L ) and bonding electron density ( n b L ). Such unique identification is made through the use of well-established relationships connecting surface tension, compressibility, and molar volume of a metallic liquid with bonding charge density. The electronegativity is obtained through a consistent linear scaling procedure. The preliminary set of values for ϕ L and n b L , together with other auxiliary model parameters, is subsequently optimized to obtain a good numerical agreement between calculated and experimental values of Δ o H f L for sixty liquid transition metal alloys. It is found that, with few exceptions, the use of liquid-specific model parameters in Macroscopic Atom Model yields a physically consistent methodology for reliable estimation of mixing enthalpies of liquid alloys.