The dependence on the annealing temperature, T a n n, of the Al asymptotic substitutional fraction φ∞ in implanted silicon carbide (4H–SiC), is addressed from a statistical mechanical point of view. Concepts relating to the cooperative nature of atomic motion in (extremely) viscous liquids or in plastic crystals are applied for the first time in describing Si⇄ Al substitution and the tendency of the system towards a regularization of its crystalline structure during annealing. The worked out model, although inspired by Al/4H–SiC literature data, can be applied to similar systems with the due changes. The slope Δ E s of the Arrhenian ln φ∞ vs. 1/k B T a n n dependence encompasses both the energy that would characterize a single Si⇄ Al ideal substitution in a regular lattice, and a negative contribution associated to the irregularity of the lattice at the substitution sites. The early evolution of the substitutional fraction φ (t; T a n …