Spinodal decomposition is a process where an initial homogeneous but unstable mixture spontaneously separates into two or more stable phases with a distinctive arrangement termed \textit{spinodal structure}. This process can be modeled with the Cahn-Hilliard equation [1] which is based on the definition of a chemical energy density depending on an order variable, i.e. the phase field, representing the smooth transition between the unstable initial mixture and the stable phases. Spinodal structures are characterized by a length scale that, if no competing processes are accounted for, coarsens over time until complete segregation of the stable phases. Recent studies suggest that for certain mixtures involving a solid matrix, the elastic parameters of the matrix govern the coarsening stage and can even arrest it, a phenomenon that is denoted as elastic microphase separation [2]. In this work, we propose a phase-field model that captures the main features of elastic microphase separation observed in [2]. We extend the Cahn-Hilliard free-energy functional [1] to include the elastic strain energy density as well as an additional coupling term. The model is first investigated in 1D and the results show that the mechanical deformation controls both the composition of the stable phases and the initial characteristic length of the spinodal structure. Moreover, we numerically show that the proposed coupling is able to predict the arrest of the coarsening phase at a length scale controlled by the model parameters. The formulation is then extended to the multi-dimensional setting and compared to experimental results. The numerical results show excellent agreement with the experimental evidence, especially in terms of initial and arrested pattern morphology. [1] J. Cahn, and J. Hilliard, 1958, { Free Energy of a Nonuniform System. I. Interfacial Free Energy.} { J. Chem. Phys.} Vol 28, No 2. [2] {C. Fernandez-Rico, S. Schreiber, H. Oudich, C. Lorenz, A. Sicher, T. Sai, V. Bauernfeind, S. Heyden, P. Carrara, L. De Lorenzis, Robert W. Style, and Eric R. Dufresne}, 2023, {Elastic microphase separation produces robust bicontinuous materials} {Nat.Mater.} issn.1476-4660 pp. 1–7