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

Abstract

A dual-phase reinforced Cu-0.75 wt% Al 2 O 3 -0.75 wt% TiB 2 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 Al 2 O 3 particles with a size of 50～500 nm and irregular polygonal TiB 2 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. • A Cu-0.75 wt% Al 2 O 3 -0.75 wt% TiB 2 composite ingot is prepared by liquid phase in-situ reaction casting method. • The combination of hot working and high cold working can effectively improve the particle distribution of the composite. • The strengthening mechanisms are dislocation, dispersion and grain boundary strengthening in descending order.