Welcome to the Phase-field code wiki!
I have three separate repositories on GitHub which are related to Phase-Field code: -
For the formulation of Cahn-Hilliard and Allen-Cahn equation, I would recommend Prof. M P Gururajan's NPTEL course on Phase field modelling and checking out the videos on the derivation of Cahn-Hilliard equation, and numerical solution of Spinodal Decomposition and Order-Disorder transformation, and Grain Growth in 2D. He has explained the formulation and implemented the solver in Octave. I have borrowed the algorithms for those video lectures and implemented the same in C.
As for the Variable Mobility Cahn Hilliard equation, you can refer to the original article by Zhu et al. I borrowed the variational formulation and the numerical technique, namely, the semi-implicit Fourier spectral technique from their paper and implemented the formulation in C.
The C code has two dependencies: