On microstructures and mechanical properties of automotive (Graphtie-TiB2)/Cu composites with different milling times

Copper (Cu) matrix composites are the most attractive materials in rail transit, aerospace and other fields because of their excellent electrical conductivity and strength. The aim of this study was to determine the effect of milling time on the microstructure and mechanical properties of the (Graphtie-TiB)/Cu composites. The composites were prepared using rapid hot pressing sintering at the milling time of 4, 6, 8, 10 and 12. The structural, physical and mechanical properties of the composites was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and compression test. The results revealed that the particles size decreased with an increase in milling time, especially the particles size drop sharply during the first 4 h of milling, and the particles size directly decreased from 44.3 μm to about 13.2 μm. The full width at half maximum of diffraction peak increased gradually with an increase in milling time. The relative density, hardness, elastic modulus, electrical conductivity and compressive strength of the composites reached the maximum at 6 h, which were 99.1 %, 86.6 HV, 137.1 GPa, 45.6 %IACS, and 228.8 MPa, respectively. Compared with 12 h, the hardness, electrical conductivity and compressive strength at 6 h were increased by 5.7 %, 79.4 % and 56.9 %, respectively. Finally, the fracture mechanism of the composites was analyzed by observing the fracture morphology.