Electron Theory in Alloy Design PDF

The past decade has witnessed a revolution in the ability of electron theory to predict numbers and provide concepts that are of direct import to understanding the structural, mechanical and magnetic properties of metals and alloys. As recently as 1962 William Hume-Rothery was stressing 'the extreme difficulty of producing any really quantitative electron theory'. The breakthrough came, in fact, two years later when Pierre Hohenberg, Walter Kohn and Liu Sham showed that it was possible to transform the complicated many-electron problem into an effective one-electron problem which could, in principle, be solved within the so-called Local Density Approximation. The advent of fast computers and improved numerical algorithms now allows the routine solution of these equations and reliable prediction of ground state properties such as the heat of formation, planar fault-energies, shear moduli and magnetic anisotropy. In addition, this new found ability for making accurate predictions has been accompanied by the development of simple, yet .reliable Nearly Free Electron or Tight Binding models which provide direct physical and chemical insight into the origin of bonding and structure at the atomistic level.

The purpose of this book is to present these new developments in electron theory which are now starting to make an impact on the search for novel alloys with improved mechanical or magnetic properties. It was produced as an accompanying volume to a two day short course at Imperial College from 14-15 September 1992. We wish to thank Keith Wakelam and Peter Danckwerts of The Institute of Materials for their unfaltering help and good cheer in keeping to the very tight publishing schedule. We also thank the European Office of the US Office of Naval Research for financial assistance. Finally we wish to thank Professor David West and Professor Harvey Flower of the Department of Materials at Imperial College, the former for suggesting the timeliness of such a course, the latter for helping to put the course together on the ground.

Edited by: D.G. Pettifor, A.H. Cottrell