Effect of Fe/Mn microalloying on the microstructural evolution and performance of Cu–Fe–Mn–P alloys

This thesis focuses on Cu–Fe–Mn–P copper alloys. Three quaternary alloys with different Fe/Mn ratios (FMP111, FMP121, FMP211) were designed and fabricated to systematically investigate the effects of Fe/Mn ratio on microstructural evolution, mechanical properties, and electrical conductivity during thermomechanical processing (hot rolling, solution treatment, and aging). Phase-diagram analysis was performed using Pandat, and multiple characterization techniques including EDS, OM, SEM, EBSD, and TEM were employed to elucidate the roles of Fe and Mn in grain refinement, precipitation kinetics, and strengthening mechanisms. The results show that the synergistic addition of Fe and Mn significantly regulates the morphology and distribution of precipitates, enabling an optimized balance between hardness and electrical conductivity. The precipitation kinetics of all alloys follow the Avrami equation; higher Fe content facilitates precipitation strengthening and accelerates the kinetic process, while Mn promotes precipitate refinement and increases their number. By judiciously designing the Fe/Mn ratio, the high-strength, high-conductivity performance of Cu–Fe–Mn–P alloys can be synergistically optimized, providing a theoretical basis for the development and application of new copper alloys.