Phase diagram databases

Max Hansen and His Succe, sors Phase Diagram Databases 493 13-2.4 Other pecialised Database and the Use of Computers 497... 

Lacking complete information on a given system, there are other avenues available for the preliminary investigation of the phase diagram. A thorough search of the literature may turn up individual phases in the system. While we have not yet reviewed X-ray crystallography, there are several crystallographic databases that provide valuable information. The first of these is the... 

The identification of the superconducting phase YBagCug-O7 g provides an example in which knowledge of thermodynamics, i.e. the Gibbs phase rule and the theory of equilibrium phase diagrams coupled with X-ray diffraction techniques led to success. Further, the use of databases that can now be easily accessed and searched on-line provided leads to a preliminary structure determination. The procedures outlined here are among the basic approaches used in solid state chemistry research, but by no means are they the only ones. Clearly the results from other analytical techniques such as electron microscopy and diffraction, thermal... 

Common approaches for the tailoring of nonmetallic (ceramic) materials properties involve topochemical methods (those where the crystal structure remains largely unaffected) and the preparation of phases in which one or more sublattices are alloyed. In principle, such materials are within the realm of CALPHAD. On the other hand, as has already been stated, extrapolation does not really aid the discovery of new or novel phases, with unique crystal structures. Furthermore, assessed thermochemical data for the vast majority of ceramic systems, particularly transition metal compounds, are presently not available in commercial databases for use with phase diagram software. This does not necessarily preclude the use of the CALPHAD method on these systems However, it does require the user to carry out their own thermodynamic assessments of the (n — 1 )th-order subsystems and to import that data into a database for extrapolation to nth-order systems, which is not a trivial task. 

The authors have described some fundamental procedures to evaluate the solid-liquid phase relations of nano-sized particles in binary alloys from the calculation of the surface properties as well as the phase equilibira on the basis of thermodynamic databases, which are usually used for the calculation of phase diagrams of the bulk materials. In order to obtain quantitatively precise values of the melting points and liquidus temperatures in alloys, we should carry out further investigation as follows ... 

We can, however, evaluate the phase equilibria of small particles qualitatively from the macroscopic thermodynamic point of view as described in the present paper. Thus, the authors wish that enormous attention be paid to the application of thermodynamic databases to the calculation of the phase diagrams of the nano-sized particles, whose information will be in demand increasingly in the near future. 

One of the most powerful aspects of the HCToolkit is its extensibility in Perl. This allows rapid development of new applications for specific tasks. For example, an included extension quickly calculates and plots a pressure-temperature phase diagram at user-specified conditions (PT-PhaseDiagram.pl, found in the /apps subdirectory of the distribution tree). In fact, a scripting application that does some sort of equilibrium calculation needs only do four things create a database connection, use that connection to load a pre-defined fluid, initialize the flash object and do the flash calculation. These steps are shown in Figure 4. 

Knowledge of the phase diagrams for compoimds of technical interest and of the environmental phases in contact with these compounds is the key for materials development and for the understanding of materials behavior in application. Not only can the thermal stability of particular phases be calculated by means of thermodynamic data, but suitable sintering procedmes can also easily be considered, and decomposition in aggressive media can be predicted. Generally recommended data books on binary and ternary systems are, e.g., those by Hansen [57], Elliott [58], Shunk [59], Mofatt [60, 61], Massalski [62], and Petzow and Effenberg [63]. Nowadays, the thermodynamic data of most of the important phases are available in publications or databases and can be readily used for thermochemical calculations. 

Cha] Chatteijee, N., Kmger, R., Haller, G., Olbricht, W., The Bayesian Approach to an Internally Consistent Thermodynamic Database Theory, Database, and Generation of Phase Diagram ,... 

Wan2] Wang, C.P., Liu, X.J., Ohnuma, I., Kainuma, R., Ishida, K., Thermodynamic Database of the Phase Diagrams in Cu-Fe Base Ternary Systems , J. Phase Equilib. Diffiis., 25(4), 320-328 (2004) (Calculation, Phase Diagram, Thermodyn., 40)... 

The solution of problems in phase equilibrium is facilitated enormously if the phase diagram is known. Several systems have been studied experimentally and the results have been collected in extensive databases. However, given the inexhaustible variety of components, compositions, temperatures, and pressures, the chemical engineer will invariably be faced with components, or conditions, for which such data are not available. A main goal in much of the rest of this book is the development of methods to predict phase behavior where data are not available. 

To predict the solid solubihty, in addition to model-based property models, databases and numerical solvers are necessary. To better illustrate each step of the solid solubility calculation, the necessary workflow and dataflow are highhghted in Figure 10.1, starting with the necessary pure component properties and ending with the phase diagram generation. It is important to note that when the experimental values of the... 

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