Preparation, bubbles evolution, and compressive mechanical properties of copper-coated carbon fibers/aluminum foam sandwich panels

As widely used energy-absorbing protective materials, the application of aluminum foam sandwich (AFS) panels remains constrained by the inherently low mechanical properties of the foam core. The incorporation of copper-coated carbon fibers (Cf) has proven to be effective in improving the mechanical properties of aluminum foam. Yet, the understanding of its foaming process and microstructure is still limited. In this work, AFS and Cf/AFS were fabricated by the packing rolling powder metallurgy method. The foaming behavior of AFS and Cf/AFS during elevated temperatures was in situ observed using synchrotron radiation X-ray imaging technology to investigate the effect of Cf on bubble nucleation, growth, and foam stability. Furthermore, the macroscopic pore size distribution, microscopic microstructure, and compressive mechanical properties of AFS and Cf/AFS were analyzed. The results showed that the existence of Cf greatly increases the nucleation rate, improves the foaming stability, and prevents the formation of localized abnormally large bubbles during the early nucleation and growth process. Meanwhile, Cf/AFS exhibited finer pore diameters and fewer pore defects than AFS. The distribution of Cf with excellent wettability along the pore wall prevented liquid film rupture and reduced coalescence. The compression experiment indicated that, in comparison to AFS, the compressive strength and energy absorption capacity of Cf/AFS have increased by approximately 40.6% and 84.8%, respectively.