Effect of TiC particle size on the microstructure and properties of CuCr-TiC composites manufactured by powder metallurgy

Poor thermal stability limits the application of CuCr alloys at high temperatures. In this work, non-stoichiometric TiC particles (7 vol%) reinforced CuCr matrix composites were fabricated. The effects of TiC powders with different particle size (1 mu m, 2 mu m, 4 mu m) on the microstructure and properties were studied. The diffusion of supersaturated Ti atoms induced the formation of Cu (Ti) solid solution transition layer at the interface, which improved the interface bonding. Dislocations caused by thermal mismatch promoted heterogeneous nucleation, which led to the precipitation of coarse Cr clusters. The strength and plasticity of composites increased with the reduction of TiC particle size. Strengthening and fracture mechanisms were discussed, and the strength difference was mainly attributed to thermal mismatch strengthening. Meanwhile, TiC particles refined the matrix grains and improved the activation energy of grain growth. The strength and softening temperature of CuCr alloy were 520 MPa and 540 degrees C, while that of CuCr-1TiC composite were 530 MPa and 915 degrees C. CuCr-TiC composites displayed much superior thermal stability than the CuCr alloy. These findings provide practical approaches for developing particle-reinforced copper matrix composites with excellent interfacial bonding and thermal stability.