ODUSOTE YISAU ADELAJA
Publication
This study is an attempt to extract useful thermodynamic information from experimental free energy of mixing of Si–Ti binary liquid alloy at different temperatures. A number of temperature dependent thermodynamic functions are calculated in the frame of a simple approach based on a statistical mechanical model. It is reported that the thermodynamic functions of Si–Ti alloy exhibit strong negative deviation from Raoult’s law across the whole concentration range and the impact of temperatures on the liquid alloy is explained. The energetics of mixing in the alloy has been explained through the study of activity, free energy of mixing, concentration fluctuations in the long-wavelength limits, chemical short-range order and diffusion. In addition, it is also observed that the tendency for intermetallic associations, which leads to the formation of SiTi compounds, decreases with the increase in temperature. This study reinforces further that useful thermodynamic information may be obtained from experimental data obtain using FactSage Thermo-Chemical Software and databases for binary liquid alloys.
We have studied the concentration dependence of the free energy of mixing, concentration–concentration fluctuations in the longwavelengthlimit, the chemical short-range order parameter, the enthalpy and entropy of mixing of Ga–Zn, Ga–Mg and Al–Ga binaryalloys at different temperatures using a quasi-chemical approximation for compound forming binary alloys and that for simple regularalloys. From the study of the thermodynamic quantities, we observed that thermodynamic properties of Ga–Zn and Al–Ga exhibitpositive deviations from Raoultian behaviour, while Ga–Mg exhibits negative deviation. Hence, this study reveals that both Ga–Zn andAl–Ga are segregating systems, while chemical order exists in Ga–Mg alloy in the whole concentration range. Furthermore, ourinvestigation indicate that Al–Ga binary alloy have a tendency to exhibit ideal mixture behaviour in the concentration range 0<Al<0:30 and 0:7<cAl<1.
The phase diagrams of Fe–Pt and Ni–Pt liquid alloy systems show the existence of FePt and NiPt intermetallic compounds, respectively, in their solid intermediate states, and the associative tendency between unlike atoms in these liquid alloys has been analysed using the self-association model. The concentration dependences of mixing properties such as the free energy of mixing, GM; the concentration fluctuations, Scc(0) in the long-wavelength limits; the chemical short-range order (CSRO) parameter, 1; as well as the chemical diffusion,enthalpy and entropy of the mixing of Fe–Pt and Ni–Pt liquid alloys have been investigated to determine the nature of ordering in the liquid alloys. The results show that heterocoordination occurs in the alloys at all concentrations. The effect of CSRO on Scc(0) , chemical diffusion, D, and the order parameter, 1 has been considered. The ordering phenomenon in the liquidalloys is also related to the effect of the atomic size mismatch volume on Scc(0).
A study of the thermodynamic properties of Cu in molten Cu{In alloys has been explained using a compound formation model. We use the model to deduce information on thermodynamic properties of the alloy such as the Gibbs free energy of mixing, the enthalpy and entropy of mixing. In this study, we rst model the Gibbs free energy in terms of the interaction parameters. Sequel to this, the interaction parameters are utilized to quantify properties such as the concentration{concentration uctuations in the long wavelength limit, the Warren{Cowley short-range order parameter, and thechemical diusion. Both positive and negative deviations from Raoultian behavior and concentration-dependent asymmetry in the mixing properties of CuIn4 liquid alloys were reported. Our analysis suggest that the liquid alloy undergoes a transformation from an ordered (In-rich end) to segregating (Cu-rich end) state. The system also exhibits ideal behavior at the Cu-rich end.
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