Abstract: In this study, the effects of alloy composition, heat treatment temperature, and external loading on the α → γ phase transformation behavior in Fe-Cu-Mn-Ni alloys were systematically investigated. Using a phase-field modeling approach, the composition and structural distributions of both α and γ phases were examined and analyzed, represented by two sets of order parameters. The results indicate that a lower Cu concentration promotes the formation of α precipitates with Cu enrichment at the particle center, maintaining the same crystal structure as the parent α phase（i.e., the bcc structure）. In contrast, a higher Cu concentration favors the formation of γ precipitates, characterized by Cu enrichment at the particle edge and an fcc crystal structure. Moreover, the addition of small amounts of Mn and Ni to Fe-Cu alloys leads to the formation of precipitate phases with Mn/Ni compositional ring enrichment. Increasing the Mn and Ni content accelerates the phase transformation process, with Mn exhibiting a more pronounced effect than Ni. Furthermore, the α + γ dual-phase microstructure of Fe-based alloys can be regulated by adjusting the thermomechanical parameters and external loading. A lower aging temperature or a faster cooling rate results in earlier initiation of the phase transformation, as well as earlier Cu enrichment at the particle edges during precipitate growth. Additionally, increasing external loading promotes the formation of Cu-enriched γ phases. These findings provide theoretical support for optimizing the performance of Fe-Cu-Mn-Ni alloys and offer a reference for phase-field modeling studies on other multicomponent alloy systems.

Key words: Fe-Cu-Mn-Ni alloys, ring structure, processing parameter, under cooling, phase-field simulation