The visualization and use of electronic structure for metallurgical applications

While the application of electronic structure theory has significantly impacted many areas of technology, including those concerned with materials development, it has not proved to be a truly useful tool of the metallurgist. We believe that this is a consequence of the specialized concepts and vocabulary in which the results of electronic structure calculations are framed and communicated. These specialized concepts have not been integrated easily into the metallurgical tool kit, which makes primary use of structure property relationships. In this paper, we present a new way of visualizing the electronic structure of a metal or alloy. This approach extends the concept of crystal structure, making it a continuous variable of quantum mechanically determined parameters of the charge density. Using the B2 transition metal-aluminides as examples, we also show that there are relationships between this extended concept of structure and phase stability. As structure can be viewed as a function of continuous variables, it is possible to determine the distance from one structure to another and from one structure to its point of instability, i.e. its phase boundary. We argue that this distance is manifested physically in terms of a metal or alloy's local elastic properties. (C) 1998 Elsevier Science S.A. All rights reserved.