Microstructure and properties of TiB2 particles reinforced Cu-Cr matrix composite

Copper-chromium matrix composites reinforced by TiB2 particles were prepared by in situ reaction between titanium and copper-boron alloy in the melt. The microstructures, mechanical, and electrical properties of the composite were investigated under as-cast and aging conditions. The results indicate that the TiB2 particles are formed by in situ reaction in matrix. The addition of TiB2 in composite reduces the segregation degree of Cr particles in matrix and inhibits the coarsening of Cr particles at high aging temperature. High hardness of Cu-Cr-TiB2 composite is achieved due to the multiple hardening mechanisms, which are in situ TiB2 particles hardening and precipitation hardening from Cr particles. The wear resistance of composite presents a dramatic improvement due to the formation of TiB2 particles, and TiB2 particles have significant effect on wear mechanism of Cu-Cr-TiB2 composite. The conductivity of composite is lower than that of Cu-Cr alloy, which is attributed to higher resistivity of TiB2 particles and the incremental interface scattering caused by TiB2 particles. But the composites with high TiB2 content still have considerable conductivity after aging.