In situ SR-CT study of interfacial behavior of AlCoCrFeNi/Al composites during microwave sintering

Abstract

The trade-off between metal strength and ductility has always been a huge challenge. This study used high entropy alloys (HEAs) to enhance aluminum matrix composites (AMCs) system, and induced interfacial evolution between particles through microwave sintering technology, forming a unique core-shell structure of HEAs/interfacial layer. This structure can effectively transfer loads and help improve material strength while maintaining good ductility. The study utilized advanced characterization techniques such as synchrotron radiation computed tomography (SR-CT) to reveal the interface behavior evolution mechanism of AlCoCrFeNi particle reinforced aluminum matrix materials. Research has shown that in addition to temperature effects, the microwave electric field and particle characteristics also play an important synergistic regulatory role in the interface evolution behavior during microwave sintering. Specifically, the microwave electric field produces an electric field focusing effect at the vertical interface gap between particles, with an electric field strength of up to 5.85 × 10⁵ V/m, inducing the interface evolution to exhibit directional selectivity, thereby strengthening interface bonding and regulating the morphology of the core-shell structure. In addition, the geometric parameters of particles (such as volume, curvature) and their spatial arrangement further affect the growth rate of the shell layer by changing the electric field distribution (for example, HEAs particles with a diameter of about 15 μm can achieve complete diffusion at a sintering temperature of 475 °C, and their evolution rate is significantly faster than that of large particles).This study provides a new theoretical basis and technical approach for optimizing the strength and ductility matching of composite materials from the perspective of interface diffusion dynamics and electric field regulation mechanism.