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Using the new Picker flow calorimeter, the excess heat capacity (C(,p)('E)) has been measured for systems containing normal, branched and cyclic alkanes. The results indicate two unusual effects: (1) a large negative contribution due to the destruction of orientational order in a pure n-alkane component, and (2) a positive contribution attributed to the "condensation" of a more freely-moving molecule or segment on a sterically-hindered branched alkane, resulting in a restriction of rotational movement, i.e. creation of order in the solution. Mixtures of cycloalkanes and their methyl derivatives also show unexpected positive effects in the excess heat capacity. Thus the plate-like cyclopentane molecule gives positive C(,p)('E) values when mixed with other plate-like methyl derivatives of cyclohexane suggesting a hindering of its molecular rotation. / Cyclohexane mixed with globular branched and cyclic alkanes shows S-shaped C(,p)('E) curves, negative at low concentration of cyclohexane but positive at high, indicating the possibility of a restriction of cyclohexane motion. / Effects of order are also apparent in the equation of state of a liquid. The thermal pressure coefficient for systems containing n-hexadecane has been found to be anomalous and is explained by a lowering of the internal energy of n-hexadecane by orientational order. / Excess volume (V('E)) has been studied for systems of branched and normal alkanes by investigating different effects contributing to the total V('E), particularly an important effect of a difference in thermal pressure coefficients of the two components.

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Indiana University-Purdue University Indianapolis (IUPUI) / Heat generation is a major safety concern in the design and development of Li ion batteries (LIBs) for large scale applications, such as electric vehicles. The total heat generation in LIBs includes entropic heat, enthalpy, reaction heat, and heat of mixing. The main objective of this study is to investigate the influence of heat of mixing on the LIBs and to understand whether it is necessary to consider the heat of mixing during the design and development of LIBs. In the previous research, Thomas and Newman derived methods to compute heat of mixing in LIB cells. Their results show that the heat of mixing cannot be neglected in comparison with the other heat sources at 2 C rate. In this study, the heat of mixing in different materials, porosity, particle sizes, and charging/discharging rate was investigated. A COMSOL mathematical model was built to simulate the heat generation of LIBs. The LIB model was based on Newman’s model. LiMn2O4 and LiCoO2 were applied as the cathode materials, and LiC6 was applied as the anode material. The results of heat of mixing were compared with the other heat sources to investigate the weight of heat of mixing in the total heat generation. The heat of mixing in cathode is smaller than the heat of mixing in anode, because of the diffusivity of LiCoO2 is 1 ×10-13 m2/s, which is larger than LiC6's diffusivity 2.52 × 10-14 m2/s. In the comparison, the heat of mixing is not as much as the irreversible heat and reversible heat, but it still cannot be neglected. Finally, a special situation will be discussed, which is the heat of mixing under the relaxation status. For instance, after the drivers turn off their vehicles, the entropy, ix enthalpy and reaction heat in LIBs will stop generating, but the heat will still be generated due to the release of heat of mixing. Therefore, it is meaningful to investigate to see if this process has significant influence on the safety and cycle life of LIBs.

The aim of this study is to form a theoretical model for simulation of glass forming ability of Fe &amp / #65533 / Based bulk amorphous alloys, to synthesize Fe &amp / #65533 / based multicomponent glassy alloys by using the predictions of the theoretical study, and to analyze the influence of crystallization and solidification kinetics on the microstructural features of this amorphous alloys. For this purpose, first, glass forming ability of Fe &amp / #65533 / (Mo, B, Cr, Nb, C) &amp / #65533 / X ( X = various alloying elements, selected from the periodic table) ternary alloy systems were simulated for twenty different alloy compositions by using the electronic theory of alloys in pseudopotential approximation and regular solution theory. Then, by using the results of the theoretical study, systematic casting experiments were performed by using centrifugal casting method. The alloying elements were melted with induction under argon atmosphere in alumina crucibles and casted into copper molds of different shapes. Characterization of the cast specimens were performed by using DSC, XRD, SEM, and optical microscopy. Comparison of equilibrium and nonequilibrium solidification structures of cast specimens were also performed so as to verify the existence of the amorphous phase. Good agreement of the results of experimental work, with the predictions of the theoretical study, and the related literature was obtained.

The aim of this study is to synthesize and characterize new bulk amorphous alloys in the Ni- based systems. Theoretical studies on the basis of semi-empirical rules and the electronic theory of alloys in pseudopotential approximation has been provided in order to predict the impurity elements that will lead to an increase in the glass forming ability of Ni-based alloy systems. Glass forming ability of ten different compositions of alloys of Ni-Nb, Ni-Fe, Ni-B, Ni-Hf and Ni-Cr was simulated by using FORTRAN programs based on pseudopotential theory. In addition to the binary alloys, ternary alloys, which were formed by addition of 1 at% of third element to these systems, were also simulated. Since ordering energy is an indicator of glass forming ability, theoretical studies allowed to predict the effect of various third elements on the formation of amorphous phase. Furthermore, ordering energies were also used to calculate other parameters important for glass forming ability. In the second part of the study, on the basis of theoretical results, a series of casting experiments were done. Different compositions of Ni-Nb, Ni-Nb-Sn and Ni-Nb-Al alloys were cast in the centrifugal casting machine. Alloys were melted in alumina crucibles and cast into the copper moulds. Characterizations of cast alloys were done by the use of Metallography, SEM, XRD and DSC. Fully amorphous Ni52Nb41Al7 alloy was synthesized in bulk form with 0.8 mm thickness.