Background <p>When subjected to tensile stress at elevated temperatures, precipitation-strengthened Ni-based single crystals exhibit the elongation in shape, coarsening in size, and more intriguingly rafting of the L1₂-structured γ' precipitates, accompanied by the formation of face-centered-cubic γ matrix bands oriented perpendicular or parallel to the loading direction.</p> Objective <p>Existing modeling efforts predominantly emphasize Eshelby-type configurational forces, i.e., the reduction of elastic potential energy arising from elastic interactions and interfacial dislocations. However, these analyses are mainly for the precipitate elongation, while detailed kinetic analyses remain lacking and the Herring-type self-diffusional mechanisms are generally not incorporated.</p> Methods <p>In this work, we establish a comprehensive chemomechanical framework that integrates both Eshelby and Herring formalisms. Guided by extensive experimental parametric studies spanning a wide range of temperatures and loading rates, a mechanistic phase diagram is identified that distinctly separates elongation and rafting regimes.</p> Conclusions <p>Energetic and kinetic comparisons demonstrate that rafting is governed by a stress-gradient-controlled self-diffusional process, rather than by the Eshelby-type species-diffusional mechanism. This unified framework not only rationalizes the experimentally observed mechanistic phase diagram but also clarifies the distinct physical origins of elongation and rafting in Ni-based single-crystal superalloys.</p>