Microstructure, properties and strengthening mechanism of Cu-TiB2-Al2O3 composite prepared by liquid phase in-situ reaction casting

A dual-phase reinforced Cu-0.75 wt% Al2O3-0.75 wt% TiB2 composite ingot was prepared by liquid phase in- situ reaction casting method and then processed by hot rolling and cold rolling. The microstructure and property evolution of the composite during processing were investigated, and the strengthening mechanism was determined. Spherical Al2O3 particles with a size of 50～500 nm and irregular polygonal TiB2 particles with a size of 50 nm～1.5 µm were formed in the Cu matrix. When the cold rolling reduction exceeded 80%, the strengthening particles flowed with the plastic flow of the Cu matrix. The violent shear action between the particles and the Cu matrix made the particle agglomerations separate, which enhanced the uniform dispersion of strengthening particles. For the reduction of 90%, the tensile strength, yield strength, hardness, elongation and electrical conductivity were 477 MPa, 452 MPa, 158 HV, 5.7% and 80.0%IACS respectively. The strengthening mechanisms were dislocation strengthening, dispersion strengthening and subgrain strengthening in descending order. Liquid phase in-situ reaction casting combined with large-deformation rolling is a promising process for the preparation of dual-phase reinforced dispersion strengthened copper matrix composite.