Diffusion.

Two well known pillars of a course on Materials Science are Thermodynamics (and phase diagrams) and Kinetics (and phase transformations): both are required to describe the formation of microstructures, in order to understand and predict the resulting macroscopic properties. Kinetics laws depend on a detailed knowledge of the mechanisms of atoms (ions, molecules, point defects…) migration and on some related basic parameters, namely the coefficients of diffusion and their temperature dependence.

Jean Philibert
Principal Editor.

A foreword by Jean Philibert.

There are several text-books on Diffusion, which follow different paths: either more atomistic or rather macroscopic with emphasis on different applied topics.Teaching experience reveals that the students are too often facing a lot of difficulties to understand basic concepts and their relations with macroscopic laws. They need to broaden their understanding by getting a look at various approaches and treating several practical cases thanks to exercises, simulations, programming. The purpose of the present pages is to offer a choice as large as possible of these various kinds of documents and references.

Two other aspects, often neglected, should be underlined : first the historical one. Information on the genesis of concepts and models and on the scientists who introduced them must be more widely spread. Most of these concepts and models appear so clear for us now (may be not so straightforward for our students !),but as history reveals it, their genesis was full of pitfalls. The other aspect, which also deserves the attention of the teachers – and which could be more attractive to students minds - is related to the general validity in many fields of science of the random walk approach as well as the generality of a diffusion equations in quite different fields of science and technology , which at a first glance have nothing to do with stricto sensu atomic diffusion, e.g. pollution, epidemics, migrations, stock quotations, or the Diffusion Weighted IRM (a new tool for the investigation of the brain) and so on…

This is a very ambitious program, which will require a large spectrum of documents. It has already been partially accomplished thanks to contributions of the colleagues who allowed their documents to be published on this "E-Materials" site. We hope their example will be followed by many others. We are also expecting from all of our readers suggestions and criticisms in order to make this pages still more useful.