scholarly journals Chemical Ordering of Ag-Au Alloys in the Molten State

2018 ◽  
Vol 22 (2) ◽  
pp. 191-201 ◽  
Author(s):  
Ishwar Koirala
Keyword(s):  
Surface Tension ◽  
Wave Length ◽  
Energy Parameter ◽  
Surface Concentration ◽  
Heat Of Mixing ◽  
Temperature Dependent ◽  
Chemical Ordering ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Structural Behaviors

Simple statistical model has been used to report the thermodynamic, structural, transport and surface properties of liquid Ag-Au alloys at 1350K. In thermodynamic properties we have studied the free energy of mixing, heat of mixing, entropy of mixing and the chemical activity of both components of the alloys. For the structural investigation, our study includes concentration fluctuation in long wave length limit and Warren-Cowley short range order parameter. Viscosity and diffusivity of the alloys have been studied to understand transport properties. The surface behavior has been analyzed by computing surface concentration and surface tension of the alloys. The structural behaviors of the alloys are found to be symmetric with respect to concentrations of the species. The computed results are in good agreement with experimental data. Positive deviation of viscosity isotherms from linear law is observed. Surface tension of the alloys is found to be smaller than ideal values throughout bulk concentration of silver. For all theoretical analysis, concentration independent energy parameter takes important role, which is found to be temperature dependent and finally analysis confirms that presented alloy is hetero-coordinated.Journal of Institute of Science and Technology Volume 22, Issue 2, January 2018, Page: 191-201

scholarly journals Chemical Ordering in In-Sn Liquid Alloy

2014 ◽  
Vol 14 (2) ◽  
pp. 161-164 ◽  
Author(s):  
D Adhikari
Keyword(s):  
Liquid Alloy ◽  
Short Range ◽  
Heat Of Mixing ◽  
Temperature Dependent ◽  
Long Wavelength ◽  
Energy Parameters ◽  
Chemical Ordering ◽  
Weakly Interacting ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

Quasi-chemical expression has been used for weakly interacting compound forming binary alloy to obtain energy parameters and their temperature derivative for In-Sn liquid alloy at 700 K. These energy parameters have then been used to calculate thermodynamic functions, such as free energy of mixing, heat of mixing, entropy of mixing and microscopic functions, such as concentration fluctuation in long wavelength limit, Warren-Cowely short range order parameter. The analysis reveals that the energy parameters are temperature dependent and the In-Sn liquid alloy at 700 K is weakly interacting heterocoordination system. The observed thermodynamic properties of In-Sn alloy in molten state have been successfully explained by assuming 3 In Sn complex on the basis of the quasichemical formalism for weakly interacting system. DOI: http://dx.doi.org/10.3126/njst.v14i2.10431   Nepal Journal of Science and Technology Vol. 14, No. 2 (2013) 161-164

scholarly journals Thermodynamic, structural, transport and surface properties of Pb-Tl liquid alloy

BIBECHANA ◽  
2015 ◽  
Vol 13 ◽  
pp. 100-113 ◽  
Author(s):  
SK Yadav ◽  
LN Jha ◽  
D Adhikari
Keyword(s):  
Liquid Alloy ◽  
Surface Concentration ◽  
Heat Of Formation ◽  
Concentration Fluctuation ◽  
Heat Of Mixing ◽  
Long Wavelength ◽  
Wavelength Limit ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Experimental Values

Thermodynamic properties, such as free energy of mixing, heat of mixing, entropy of mixing, activities and the microscopic structural properties, such as concentration fluctuation in long-wavelength limit and chemical short-range order parameter of Pb-Tl liquid alloy at 773 K have been studied on the basis of regular associated solution model. We have estimated the mole fractions of the complex and the unassociated atoms assuming the existence of  complex as energetically favoured in the liquid state. The compositional contributions of the heat of mixing of the species Pb and Tl and the heat of formation of the compound to the net enthalpy change have also been studied. The transport properties such as, viscosity and the ratio of mutual and intrinsic coefficients have been studied using different approaches. The surface concentration of Tl atoms has been computed and it has been employed to calculate the surface tension of Pb-Tl liquid alloy. Both the theoretical and the experimental values of the concentration fluctuation in long-wavelength limit are found to be less than the ideal value, revealing that the concerned system is hetero-coordinating in nature. The interaction energies are found to be temperature dependent and respective alloy is found to be weakly interacting system. BIBECHANA 13 (2016) 100-113

scholarly journals A Theoretical study of thermodynamic properties of Cd-Bi liquid alloy

BIBECHANA ◽  
1970 ◽  
Vol 8 ◽  
pp. 90-95
Author(s):  
D Adhikari
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Liquid Alloy ◽  
Theoretical Study ◽  
Energy Parameter ◽  
Heat Of Mixing ◽  
Liquid Alloys ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Good Agreement

Flory’s model has been used for the study of thermodynamic properties of Cd-Bi liquid alloys. Free energy of mixing, heat of mixing, entropy of mixing and activity of Cd have been determined. All of these computed quantities have been found to be in a good agreement with observed values.Keywords: Flory’s model; thermodynamic properties; Cd-Bi liquid alloy; weakly interacting system; interaction energy parameter  DOI: http://dx.doi.org/10.3126/bibechana.v8i0.5693  BIBECHANA 8 (2012) 90-95

scholarly journals Thermodynamic, structural, surface and transport properties of Zn-Cd liquid alloy at 800 K

BIBECHANA ◽  
2016 ◽  
Vol 14 ◽  
pp. 54-65 ◽  
Author(s):  
K K Mishra ◽  
H K Limbu ◽  
B Yadav ◽  
A K Khan ◽  
I S Jha ◽  
...  
Keyword(s):  
Wave Length ◽  
Heat Of Mixing ◽  
Size Factor ◽  
Mixing Properties ◽  
Binary Liquid ◽  
Long Wave ◽  
Energy Of Mixing ◽  
Alloy Increase ◽  
Structural Surface ◽  
Free Energy Of Mixing

The mixing thermodynamic and structural properties of Zn-Cd liquid at 800K has been studied using Flory’s model. To explain the mixing properties of binary liquid alloys, size factor (ф) and ordering energy (ω) are taken into account. Thermodynamic properties like free energy of mixing (GM), activity (a), Heat of mixing (HM) and entropy of mixing (SM) and the microscopic properties like concentration fluctuation in the long wave length limit (Scc(0)) and chemical short range order parameter (α1) have been calculated. Surface property has also been studied with the help of Buttler’s model. The viscosity of the melt has been computed from Kaptay equation and BBK models. Both the viscosity and surface tension of the alloy increase with addition of zinc- component. BIBECHANA 14 (2017) 54-65

scholarly journals Mixing properties of Ni-Pd liquid alloy

BIBECHANA ◽  
2013 ◽  
Vol 10 ◽  
pp. 108-114
Author(s):  
L Gurung ◽  
RP Koirala ◽  
D Adhikari
Keyword(s):  
Liquid Alloy ◽  
Energy Parameter ◽  
Simple Theory ◽  
Heat Of Mixing ◽  
Structural Behaviour ◽  
Mixing Properties ◽  
Long Wavelength ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Alloy Concentration

In this work, thermodynamic and microscopic properties of Ni-Pd liquid alloy at 1873 K have been studied using a simple theory of mixture. In thermodynamic properties, free energy of mixing, heat of mixing and entropy of mixing have been studied. To understand the structural behaviour of the alloy concentration fluctuation in long wavelength limit and chemical short range order parameter have been computed. The Ni-Pd melt at 1873 K is found to be slightly deviated from regular behaviour. The best estimated value of energy parameter is found to be positive. The alloy is found to be weakly segregating system. The symmetric behaviour of all functions has been well explained by the simple theory of mixing. DOI: http://dx.doi.org/10.3126/bibechana.v10i0.9341   BIBECHANA 10 (2014) 108-114

scholarly journals Thermodynamic and structural investigations on mixing behavior of hetero-coordinated Al-based alloys in the fusion state

BIBECHANA ◽  
2015 ◽  
Vol 13 ◽  
pp. 87-93
Author(s):  
I Koirala ◽  
BP Singh ◽  
IS Jha
Keyword(s):  
Structural Parameters ◽  
Energy Parameter ◽  
Microscopic Level ◽  
Negative Deviation ◽  
Temperature Dependent ◽  
Structural Investigations ◽  
Long Wavelength ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Good Agreement

We have used simple statistical model to report the hetero-coordination of two Al- based liquid alloys, i.e. Al-Ge and Al-Fe at temperatures 2000K and 1873K respectively. Through thermodynamic functions such as free energy of mixing and ratio of activity of the component atoms of the alloys, we have reported the information on the interaction, stability and bonding strength among the constituent atoms in the alloys. At the microscopic level, concentration fluctuation in the long wavelength limit and Warren-Cowely short range order parameter help to obtain the microscopic information on structure of molten alloys. Our theoretical analysis is based on interchange or ordering energy parameter which is found to be negative and temperature dependent. Negative deviation from Raoultian behaviour is observed in the computed thermodynamic and structural parameters of the alloys. The computed results are in good agreement with experimental data. The analysis concluded that both alloys are of weakly interacting and chemically ordered system. BIBECHANA 13 (2016) 87-93

scholarly journals Chemical Ordering in Na-Pb and Na-Hg Binary Liquid Alloys

2017 ◽  
Author(s):  
Ayideji Akintunde Ajayi ◽  
Enoch Debayo Ogunmola
Keyword(s):  
Binary Alloy ◽  
Liquid Alloy ◽  
Energy Parameter ◽  
Liquid Alloys ◽  
Mixing Properties ◽  
Long Wavelength ◽  
Chemical Ordering ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Liquid Binary Alloy

A simple model has been used to investigate the nature of chemical order in Na-Pb and Na-Hg liquid binary alloy at 700K and 673K respectively. The energy parameter obtained from the model was used to calculate the concentration dependent mixing properties such as Gibb’s free energy of mixing, Concentration fluctuations in the long wavelength limit and the Warren-Cowley chemical short range order parameter. Results obtained showed that both alloys are hetero-coordinated throughout the entire concentration and there is tendency for segregation and demixing to take place in the liquid alloys. We observed that Na-Hg liquid alloy is more strongly interacting binary alloy and chemically ordered than Na-Pb liquid alloy.

scholarly journals Energetics and local order in In-based liquid alloys

BIBECHANA ◽  
2015 ◽  
Vol 13 ◽  
pp. 60-71
Author(s):  
RP Koirala ◽  
BP Singh ◽  
IS Jha ◽  
D Adhikari
Keyword(s):  
Thermodynamic Properties ◽  
Local Order ◽  
Heat Of Mixing ◽  
Liquid Alloys ◽  
Association Model ◽  
Long Wavelength ◽  
Energy Of Mixing ◽  
Self Association ◽  
Free Energy Of Mixing ◽  
Solution Behaviour

A comparative study has been carried out to understand the concentration dependence of thermodynamic properties such as, free energy of mixing, heat of mixing, entropy of mixing, activity  and microscopic properties, such as concentration fluctuation in long wavelength limit  and Warren-Cowley short range order parameter  of  In-based three liquid alloys (In-Pb , In-Tl and In-Zn) on the basis of self-association model. The analysis reveals that self-association model successfully explains the observed properties of the liquid alloys.  Positive deviation of the thermodynamic properties of the alloys from the Raoultian solution behaviour indicates that the alloys are weakly segregating in nature. The comparative assessment of the interaction energy and the microscopic properties suggests that the degree of segregation is greatest in In-Zn alloy and comparable in In-Pb and In-Tl alloys.BIBECHANA 13 (2016) 60-71

scholarly journals Structural study of liquid Sn-Tl alloys

BIBECHANA ◽  
2014 ◽  
Vol 11 ◽  
pp. 46-52
Author(s):  
RP Koirala ◽  
IS Jha ◽  
BP Singh ◽  
D Adhikari
Keyword(s):  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Theoretical Models ◽  
Temperature Dependent ◽  
Long Wavelength ◽  
Energy Interaction ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
The Comparative Study

The concentration fluctuations in long wavelength limit, Scc(0) and the Warren-Cowley short range order parameter (α1) are important microscopic functions which provide valuable information about the local arrangements of the constituent atoms in the alloy melts. In order to investigate the nature of atomic ordering in Sn-Tl alloy in the molten state at 723K, we have computed these functions using theoretical models. The models satisfactorily explain the small asymmetry observed in the experimental data of free energy of mixing of the alloy. The comparative study further reveals that the energy interaction parameters are temperature dependent and the Sn-Tl alloy is weakly interacting segregating system. DOI: http://dx.doi.org/10.3126/bibechana.v11i0.10379   BIBECHANA 11(1) (2014) 46-52

scholarly journals Thermodynamic Properties of InNa Liquid Alloy

1970 ◽  
Vol 6 (6) ◽  
pp. 16-18
Author(s):  
SK Chakrabarti ◽  
IS Jha ◽  
BP Singh
Keyword(s):  
Thermodynamic Properties ◽  
Liquid Alloy ◽  
Heat Of Mixing ◽  
Liquid Alloys ◽  
Atomic Composition ◽  
Binary Liquid ◽  
Scientific World ◽  
Energy Of Mixing ◽  
Large Asymmetry ◽  
Free Energy Of Mixing

The large asymmetry observed in the properties of mixing of indium-sodium liquid alloy is discussed on the basis of quasi-lattice chemical model. A special attention is given to the concentration dependence of free energy of mixing, entropy of mixing and heat of mixing. The results explain the observed asymmetry in the properties of mixing of InNa liquid alloys around equi-atomic composition. Key words: Complex forming alloys; Binary liquid alloys; Quasi-lattice model; Thermodynamic properties. DOI: 10.3126/sw.v6i6.2627 Scientific World, Vol. 6, No. 6, July 2008 16-18

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