Spinodal decomposition and dislocation lines in thin films and bulk materials

Phase separation of alloys around dislocation lines due to edge- and screw-type dislocations is studied using a continuum model. The dependence of the lattice constant, bulk modulus, and shear modulus on composition is shown to determine the distribution of the alloy components in the stress fields of the dislocations. Numerical simulation results are also presented for single dislocation lines, arrays of dislocations, and random distributions of dislocations in bulk mixtures in a context relevant to quench-work-age thermomechanical treatment of alloys. The effects of dislocations on the phase separation occurring at the surface of growing films is also discussed, showing that misfit dislocations can create a compositionally patterned layer. The equilibrium position of misfit dislocations is also calculated for compositionally modulated overlayers, and it is shown that the critical thickness for the introduction of dislocations is reduced due to the composition modulation.