Microstructural evolution and strengthening mechanisms in Cu-coated cBN reinforced aluminum nanocomposites
Mohamed I. A. Habba, Ahmed M. M. Hassan, A. Fathy, Abdelkarim Yousif Mohamed, Ramy A. Fouad, Mamdouh I. Elamy, Waheed S. Barakat
Abstract
Aluminum-based composites reinforced with ceramic particles have garnered significant attention owing to their enhanced mechanical properties. However, the poor wettability between aluminum (Al) and ceramics, particularly cubic boron nitride (cBN), often limits their performance in advanced applications. This study investigates the effect of copper-coated cubic boron nitride (Cu/cBN) nanoparticles on the microstructural evolution and mechanical properties of Al-based composites. Nanostructured Cu/cBN particles were synthesized via chemical reduction and uniformly incorporated into the Al matrix at varying contents of 0, 2.5, 5, 7.5, and 10 wt% through powder metallurgy. The composites were characterized using XRD, SEM, and EDS analyses. The mechanical properties were evaluated through Vickers hardness and compression tests. The results demonstrate that incorporating Cu/cBN particles significantly enhanced the mechanical performance. The Al-10 nanocomposite exhibited remarkable improvements: a 272.8 % increase in hardness, 378 % increase in Young's modulus, 221 % increase in yield strength, and 274 % increase in compressive strength. Microstructural analysis revealed substantial grain refinement and increased dislocation density with higher reinforcement levels. The fracture mechanism shifted from ductile to strength-dominated behavior. These enhancements are attributed to a synergistic effect of Orowan strengthening, grain refinement, and thermally induced dislocation density. The results confirm the effectiveness of Cu/cBN nanoparticles in enhancing the mechanical performance of Al-based nanocomposites for structural applications.