Investigation on microstructure and properties of Cu-Al2O3 composites fabricated by a novel in-situ reactive synthesis

Alumina (Al2O3) ceramic particles are potentially attractive as reinforcement for Cu-based composites, owing to their excellent thermodynamic stability. In this paper, Cu-2.75 vol.% Al2O3 composites were prepared by a novel in-situ reactive synthesis. The microstructures of Cu-2.75 vol.% Al2O3 composites were characterized by XRD, SEM and TEM, respectively. The results showed that the nano-scale gamma-Al2O3 particles with a mean size of 1020 nm in diameter are uniformly distributed in the Cu matrix. High resolution transmission electron microscopy (HRTEM) analysis shows that there is a crystallographic orientation relational of (20 (2) over bar )cu//(2 (6) over bar0)gamma-Al2O3 and [111](cu)/[001](gamma-Al2O3), indicating that the cubic-gamma-Al2O3 phase is coherent with Cu matrix. Particularly, the obtained composites possess superior mechanical properties. And the tensile strength, the yield strength, the Rockwell hardness and the electrical conductivity are 570 MPa, 533 MPa, 86 HRB and 85% IACS, respectively. The strengthening mechanisms, mainly consist of grain-boundary strengthening and Orowan strengthening, could be used to illustrate the improvement on the strength of the Cu-Al2O3 composites. (C) 2015 Elsevier Ltd. All rights reserved.