Tensile Properties and Fracture Mechanism of Copper Matrix Composites Reinforced by Carbon Fibres with Ni-Co-P Alloy Coating

Abstract:

The composition controlled Ni-Co-P multi-component alloy coatings with the thickness of about 0.7 μm were prepared on the surface of carbon fibres (CFs) using the palladium-free electroless plating. Then the copper matrix composites reinforced by the Ni-Co-P coated CFs, namely the CF/Cu(Ni-Co-P) composites, with CF content of 10vol%, 20vol%, 30vol%, and 40vol%, the uncoated CFs reinforced copper matrix composites (CF/Cu) with 30vol% CFs, and the Ni-coated CFs reinforced composites, namely the CF/Cu(Ni) composites, with 30vol% CFs were prepared by the vacuum heat pressure sintering at 850 °C and 30 MPa. The distribution of reinforcement and interface phase elements and the fracture morphologies of the composites were observed by the scanning electron microscope and energy dispersive spectrometer. The tensile properties of different copper matrix composites were characterized by the electronic universal testing machine. Results show that the smooth Ni-Co-P coatings of uniform thickness can be obtained on CFs surface by electroless plating at 70 °C for 10 min. The tensile properties of CF/Cu(Ni-Co-P) composites are firstly increased and subsequently decreased with increasing the CFs content. The highest tensile and yield strengths are obtained for the 30vol% CF/Cu(Ni-Co-P) composite. The mechanical properties of CF/Cu(Ni-Co-P) composite are obviously better than those of the CF/Cu and CF/Cu(Ni) composites with the same content of reinforcement (30vol%). The fracture mechanism of CF/Cu(Ni-Co-P) composite is non-accumulative fracture.

Key words:Ni-Co-P coated carbon fibres;copper matrix composites;tensile properties;fracture mechanism