Effect of La on microstructures and mechanical properties of Cu/Ti3SiC2/C nanocomposites sintered by vacuum hot-pressing and hot isostatic pressing

Researches have shown that the addition of trace amounts of rare earth element lanthanum (La) to the alloys and composites can significantly improve their microstructure and properties. In this work, Cu/Ti 3 SiC 2 /C composites with 0.05wt%, 0.1wt% and 0.3wt% La were prepared by powder metallurgy methodthrough mechanical alloying, hot-pressing (HP) and hot isostatic pressing (HIP). The effects of different La contents on the microstructure and mechanical properties of Cu/Ti 3 SiC 2 /C composites were investigated. The results show that La has a refinement effect on the grain of the matrix, and with the increase of La content, the size of the matrix of the composite becomes smaller. As the content of La increases, the performance of the composite exhibits a tendency to increase first and then decrease. The composite of 0.1wt% La exhibited the best performance with a hardness of 97.8 MPa, a tensile strength of 174.9 MPa, and a compressive strength and shear strength of 461.1 MPa and 102.1 MPa, respectively. Since the dimple is observed, the tensile fracture indicates that the fracture mode is a ductile fracture. The enhancement mechanism of La mainly includes dispersion strengthening and fine grain strengthening.