Statistical-Thermodynamic Modeling of Key Materials

A statistical-thermodynamic modeling and prediction of the behavior of intermetallic compounds and thin film materials produced on their base under various technological states is of paramount importance, since these compounds are a fascinating group of materials, from the point of view of their fundamental properties and their technological application. Therefore, a generalized, quantitative and predictive statistical-thermodynamic modeling based on an Ising approach, the Bragg-Williams random-mixing approximations and the Bethe-Guggenheim quasi- chemical approximation is proposed for description of thermodynamic behavior and ordering phenomena in bulk and nano-crystalline ordered intermetallic materials. The new modeling approach takes into account the presence of all possible defects in the structure, both vacancies and anti-structure atoms and includes a description of Long- Range Ordering and Short-Range Ordering in the crystal lattice, i.e. the possible correlation of nearest neighbor point defect combinations. The proposed new modeling approach and developed models will encompass a predictive ability and a general application to understanding of ordering processes in the structure and to improvement of the mechanical and thermodynamical properties of existing intermetallic bulk and nano-crystalline commercial materials, and also in new advanced materials discovery and development. In addition, it provides strategies for refinement of scientific concepts and carrying out the research in a productive manner, avoiding expensive or even dangerous experiments in the laboratory.

New advanced key technological materials - the intermetallic bulk and nanocrystalline alloys - are among the primary subjects in modern science and technology, since these compounds are a fascinating group of materials, both from the point of view of their fundamental properties and their practical and commercial use in high performance strategic applications. The widespread use of nanosized materials and thin films in electronic, micromechanical, magnetic and optical devices, and other industrial fields has stimulated interest in a detailed understanding of ordering processes in structure of these materials, since these processes affect the long-term stability of multi-component film structures and are the critical factors that limit their utility in future applications. Obviously, many of exceptional outstanding properties of materials in film form can be related to both the ordering phenomena in the structure and the type and amount of defects present in thermodynamic equilibrium state, and to the variation of defect concentrations with composition and temperature. The problem of the design of new materials can be reduced by the discovery of the structure-composition- processing-property relationships in intermetallic systems. Therefore, the development and application of the modeling on intermetallic compounds is a new and promising trend for the acquisition, analysis and on-line delivery of the information to the specialists. This conclusion obviously induces new theoretical studies which are performed in the present Project. The main objective is aimed toward a correct thermodynamic modeling and description of the effects and changes associated with the creation of different arrangements and defects in the crystal structure and their connection and influence on the properties of the bulk and nanostructured intermetallic systems. This modeling approach and obtained results allow to select and justify more reliable data among different contradictory literature information, and, consequently, can be applied to a rapidly evaluation a thermodynamic description of the system in question, prediction and discovery of the new phases with specific properties, and identification of key alloys for experimentation. We believe that this approach could be a viable strategy for discovery of the complex nanostructured materials with useful, unique, and anticipated properties.