Dislocation-ledge coupling governs semicoherent precipitate growth
arXiv:2602.16158
The paper investigates how dense interfacial dislocation networks move and reorganize during semicoherent precipitate growth, using in situ TEM, O‑lattice analysis, and 3D phase‑field crystal simulations to reveal diffusion‑assisted, ledge‑mediated interface migration.
Abstract
Many crystalline materials acquire their properties as one crystal phase grows through another, but a long-standing defect-kinetic puzzle remains: how dense interfacial dislocation networks between two crystals advance, reorganize, and accommodate strain without relying on ordinary glide. Here, using in situ transmission electron microscopy, O-lattice analysis, and three-dimensional phase-field crystal simulations, we identify how semicoherent interfaces overcome this constraint during lath precipitate growth. In situ observations of austenite precipitates in duplex stainless steel reveal nanometer-high growth ledges propagating laterally along migrating habit planes. O-lattice analysis shows how lattice misfit prescribes a closed network across habit planes, side facets, and end faces. Simulations resolve the hidden three-dimensional dynamics: the network undergoes diffusion-assisted, non-conservative motion, producing steady end-face advance and ledge-mediated broad-facet migration while accommodating transformation strain. These results reveal a general defect-kinetic route linking point-defect transport, dislocation-network motion, interface migration, and morphology evolution.
Revised abstract and manuscript