Resolving the long-standing discrepancy in Fe3Al ordering mobilities: A synergistic experimental and phase-field study

This study addressed the long-standing challenge of determining the growth kinetic of Antiphase Domains (APDs) with D 0 3 -ordered structure in Fe 3 Al by the combination of phase-field (PF) simulations and transmission electron microscopy (TEM) observation. The “shape coefficient” which correlates the growth rate of APD with 3-dimensional intricate shape and the shrinking rate of 2-dimensional circular antiphase boundaries (APBs) in thin film was assessed through a comparative analysis of PF simulations involving the shrinking of 2D circular APBs and the growth of 3D APDs emerged from a disordered state. Simultaneously, the increase rate in APD size in bulk samples after heat treatment was measured using TEM. By incorporating the calculated shape coefficient and experimental data on APD growth rates, we successfully derived accurate values of mobility for forming D 0 3 type ordered structure. The ordering mobilities evaluated by this approach align more closely with those obtained through traditional X-ray powder diffraction of order-order relaxation rather than those obtained through in-situ TEM observation. This finding lays the foundation for optimizing heat treatment conditions to regulate APD structure and enhance the superelasticity of Fe 3 Al primarily due to the interaction between dislocation and APBs. This methodology can be extended to estimate the ordering mobility of other intermetallic.