Effect of TiC and Ti on the microstructure and properties of CuCrNb composites with high softening temperature

Particle-reinforced CuCrNb composites have considerable significance in the field of heat resistance. In this work, CuCrNb(CCN) alloy, CuCrNb-TiC(CCN-TiC), and CuCrNb-TiC-Ti(CCN-TiC-Ti) composites were fabricated by high-energy ball milling and hot-press sintering. The effects of TiC and Ti on the microstructure and properties of CuCrNb powder metallurgy materials were studied. The results showed that submicron TiC particles promoted recrystallization and the release of intragranular energy through the particle-stimulated nucleation mechanism. Trace Ti inhibited the growth of Cr precipitates at high temperatures and Cr₂Nb particles with high thermal stability pinned the sub-grain boundaries. The softening temperature of the aged CCN-TiC-Ti composite was 930 °C. The tensile strength and elongation of CCN-TiC-Ti composite were 542 MPa and 22.2 %, respectively, which were enhanced by 77 MPa and 3.9 % compared with those of CCN alloy, respectively. The good mechanical properties of the CCN-TiC-Ti composite were derived from fine grains, high density of dislocations, and structures such as the 9 R phase, twins, and Ti-rich transition layer at the Cu/TiC interface.