A materials phenomenon
As noted in the biographical sketch published in The Selected Works of John W. Cahn (Edited by W.C. Carter and W.C. Johnson: TMS (1980)), John Cahn's life and career is
an extraordinary life and truly remarkable career of one of the world's most influential materials scientists.
Cahn's contributions to materials science include the Cahn-Hilliard and Allen-Cahn equations (for studying the kinetics of phase transformations and microstructural evolution), studies on spinodal decomposition, thermodynamics of stressed solids, quasicrystals, and critical wetting.
As has been observed in the biographical sketch referred above, "READ CAHN!" is an advice that is common among materials scientists. This article is an outcome of my efforts to read Cahn - and if it prompts you to read the master in the original, my purpose in writing this article would have been served.
The Cahn-Allen equation was introduced by Cahn and Allen in
Journal de Physique, Vol. 38, Colloque C7, C7-51 (1977),
The Cahn-Hilliard equation was introduced in the form in which it is known today by Cahn in
Acta Metallurgica, Vol 9, p. 799, (1961).
However, the free energy expression that resulted in the CH equation was discussed in great detail in the following two papers by Cahn and Hilliard (and hence the name Cahn-Hilliard):
The Journal of Chemical Physics, Vol. 28, No. 2, pp. 258-267 (1958), and
The Journal of Chemical Physics, Vol. 31, No. 3, pp. 688-699 (1959).
These three papers along with the following two - one by Cahn and the other by Hilliard are a must read for anybody who is interested in phase field modelling (the bonus is that these are extremely readable):
JW Cahn, Transactions of the Metallurgical Society AIME, Vol. 242, pp. 166-180 (1968).
JE Hilliard, Phase transformations (American Society for Metals publication, 1970), pp. 497-560.
In my opinion, the above two papers are to spinodal decomposition what Shakespeare is to English literature - And, what Shakespeare is to English literature is discussed delightfully in "The Western Canon" by Harold Bloom.
Here is Prof. Cahn's homepage at NIST.