Synthesis and characterization of an in-situ Al2O3/Al–Cu composite with a heterogeneous structure

In this paper, an Al–Cu based composite reinforced by nano α–Al2O3 particles has been synthesized by promoting liquid–solid reactions of Al–10CuO, followed by hot extrusion process. The Al2O3/Al–Cu composite was found exhibiting a heterogeneous structure after extrusion, composing of alternately distributed Al2O3 particle–rich zones and Al2O3 particle–poor zones. In the Al2O3 particle–rich zones, the in–situ formed Al2Cu and Al2O3 particles exhibit similar distribution law, which is supposed relating to the composite synthesizing process. However, after T6 heat treatment, the precipitated θ’ nano–particles were mainly found locating in the Al2O3 particle–poor zones. The ultimate tensile strength and elongation of the T6 treated Al2O3/Al–Cu composite is 420 MPa and 5.7%, respectively. Differential scanning calorimetry analysis has been carried out to reveal the reaction procedure between Al and CuO. The microstructure evolution process of the composite was discussed. This work may provide new insights for designing Al composites strengthened by ceramic particles and intermetallic compounds simultaneously.