Recent conferences (1,2) presented many applications of Computational Thermodynamics. Moreover volume 26 (2002) of the CALPHAD Journal describes a variety of software available for applying these methods. Several examples of recent work on Nb alloys (3), giant magnetoresistance (4), metallic glasses (5-7). Lithium Batteries(8,9) Zirconia Ceramics(10), and multicomponent rhenium alloys(11,12) were discussed to note current problems that require attention and to foster future progress in these fields. At these conferences (1,2) progress since 1966 (when limited capability for making useful predictions of phase equilibria in multicomponent commercial alloys existed) was contrasted with current practice where CT methods are used with success. This was attributed to the development of CALPHAD THERMODYNAMICS (CT) to describe all possible phases in a system over wide ranges of conditions uncommon in classical thermodynamics. This feature grew naturally in (CT) from the realization that commercial processing always trys to increase the rate of production to become more profitable. By contrast, thermodynamic measurements are performed under equilibrium conditions! Since (CT) applies the results of measurements and observations, made under conditions where equilibrium prevails, to commercial practice where non-equilibrium or quasi-equilibrium persists, (CT) must have a broader scope than used in classical thermodynamics. The success achieved by pursuing this track is the explicit description of the stability of unstable and metastable phases and the functional descriptions of the compositional, temperature and pressure dependences of the Gibbs energies and entropies of such phases. This feature has permitted many worker worldwide to understand and apply this framework to many important problems and to communicate their results to others. The fast, powerful PC’s and efficient software programs for performing such calculations have contributed to this progress. The (CT) descriptions of stable, metastable and unstable phases has also established in interface with ab-intio methods. Good agreement has been attained between these methods in many cases but some differences still exist. The discussion below will review the current applications of CT to several new systems as well as CALPHAD and ab-initio lattice stabilities.
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E-mail: larrykaufman@rcn.com