= Solution
At fixed transformed <volume>, an equilibrium <solid-state precipitate> seeks a low total <free energy>, including the orientation-dependent <interfacial energy> and elastic <strain> energy associated with misfit and applied <stress>. Low-energy interface orientations occupy large faces. The Wulff construction captures surface-energy <anisotropy> when <strain> and other contributions can be neglected; a <solid-state precipitate> generally also pays <coherency strain> energy, and its optimum shape can change with size.
During formation, growth kinetics and <diffusion> may prevent the equilibrium shape being reached. Coherent, semicoherent and incoherent interfaces have different bonding and defect structures, so their energies and attachment rates differ. \b[The disc shape is consistent with much cheaper broad faces than edges], but morphology alone does not uniquely measure the energies or prove equilibrium.
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