Thermodynamics of liquid Mg-Sn alloys

Abstract

AbStlllcLThe large deviation from the ideal mixture behaviour and the concenttation-dependent asymmetry in the thermodynamic properties of Mg-Sn liquid alloys is investigated within a simple theoretical model of heterocoordination (i.e. a model in which there is a preference for unlike a t o m to be paired as nearest neighbours). This has been utilized to extract additional microscopic information such as concentration fluctuations and the chemical short-range order parameter. The analysis suggests that heterocwrdination leading to the formation of chemical complexes Mg,Sn is likely to exist in the melt but is only of a weakly interacting nature. The interaction energies W e e n the species of the melt are found to depend considerably on temperature and the alloy is chemically more ordered towards the Mg-rich end of the phase diagam.

A thermodynamic model for the systemSiO2–H2Onear the upper critical end point based on quartz solubility experiments at 500–1100 °C and 5–20

“…(1) describes any aqueous oxide polymerization or depolymerization reaction, such as the dimer-monomer reaction H 2 O þ Si 2 OðOHÞ 6 ¼ 2SiðOHÞ 4 , but on a single-oxygen basis. In principle, the SiO 2 -H 2 O system could be described by a regular or subregular solution of three components -H 2 O; O 2À , and OH À , with a term added to describe the additional free energy derived from creating the OH À component, similar to the thermodynamics of liquid alloys (e.g., Singh et al, 1993). However, the three-component regular or subregular solution would require too many parameters to fit the available data.…”

Correlation between bulk and surface properties in Cd–X (X=Hg, Mg) liquid alloys

“…The calculations of enthalpy and entropy of mixing are of immense relevance since they will likely provide information on the temperature dependence of the ordering energy [25]. The expression for the entropy of mixing, SM R in the framework of QCA model for regular solution is given by…”

“…Bulk concentration-concentration fluctuations in the long-wavelength limit, S cc b (0) S cc b (0) is an essential microscopic function which has been widely used to study the nature of atomic order in binary liquid alloys [24,25]. This function is related to G M RT and activity a A via the following equation:…”

Electronic Transport and Thermodynamic Properties of Binary Liquid Alloy: Ab Initio Approach

“…Hence, a liquid metal binary alloy becomes a ternary system, consisting of free constituent ions of the component metals and chemical complex. A complex formation model [30][31][32][33][34][35][36] assumes the liquid binary alloy A À B as a ternary mixture consisting of free atoms A, free atoms B, and their preferential association-referred to as chemical complex A l B m .…”