To investigate the effects of processing parameters on phase formation and structural evolution of FeCoCrNiAl nanostructured high-entropy alloys during microwave-assisted synthesis, FeCoCrNiAl/CNTs high-entropy alloy composites were prepared by microwave-assisted heating using carbon nanotubes (CNTs) as microwave-absorbing media, and the effects of CNTs loading, microwave power, reaction temperature, holding time and cooling mode on the heating behavior, phase composition and surface chemical states of the materials were systematically examined. It was found that CNTs loading exerted a significant influence on the microwave response of the system and alloy phase formation. At a CNT content of 25 wt%, the system exhibited the most favorable heating characteristics, with a markedly enhanced FCC (111) diffraction peak and the presence of FCC/BCC dual-phase features. Increasing the microwave power significantly accelerated the heating rate, and when the reaction temperature reached 800°C, the characteristic diffraction peaks of the alloy phase became more distinct accompanied by a marked weakening of non-target diffraction signals, indicating that appropriate thermal input facilitated elemental diffusion and solid-solution formation. Extending the holding time exerted a relatively limited influence on the phase structure, whereas rapid cooling favored the retention of alloy phases formed at elevated temperatures, giving rise to sharper diffraction peaks, fewer impurity peaks, and more prominent metallic-state signals and carbon skeleton features on the surface, thereby reducing the likelihood of elemental segregation and secondary-phase precipitation during cooling. Overall, the synergistic regulation of CNTs loading and microwave thermal history governs the formation of FeCoCrNiAl high-entropy alloys, and the optimal process combination within the investigated range was identified as a CNT content of 25 wt%, a microwave power of 60%, a reaction temperature of approximately 800°C, a holding time of 10 min, and rapid cooling, which provides an experimental basis for the efficient preparation and process optimization of FeCoCrNiAl/CNTs nanostructured high-entropy alloys.

high-entropy alloys; carbon nanotubes; microwave-assisted synthesis; process optimization; phase regulation