Preparation And Properties Of Cu-NbSe₂-La₂O₃Composites

Cu matrix composites have attracted much more attention due to their excellentproperties, such as electrical and thermal conductivity, high mechanical strength and goodwear resistance, if compared with pure copper. Some researchers point out that the rareearth oxides La₂O₃can refine the grains of metal matrix composites, improving themechanical properties, wear resistance and arc erosion resistance. NbSe₂is a new kind ofmaterial with good lubrication property and electrical conductivity. Its friction coefficientis equivalent with that of graphite, while its electrical conductivity is10times than that ofgraphite, It is anticipated that NbSe₂can be used as an ideal enhancement phase in coppermatrix composites.This paper aims to fabricate a Cu-NbSe₂-La₂O₃composite by vacuum hot pressing. Itis expected to improve the properties of Cu-base composite without the decrease ofelectrical conductivity. This study mainly focused on the effects of hot press parameters,the content of the two enhancements on microstructure, mechanical properties of thecomposite materials. The microstructure and the interface were characterized by somemodern analysis technologies, including OM, SEM, EDS, HRTEM, et.al.The results show that the Cu-6%NbSe₂-0.5%La₂O₃composite obtained at sinteringtemperature of820℃and holding time of10min demonstrates superior properties. Itstensile strength is as1.40times than that of pure copper, while the electrical conductivityis no less than60%of pure copper. The friction coefficient and wear rate of Cu-La₂O₃composite were decreased significantly due to the addition of NbSe₂. An obviouslubrication film of NbSe₂was observed on the worn surface of the composite under theload of10N. The wear mechanism of the Cu-La₂O₃composite can be changed fromadhesion wear to abrasive wear with the addition of NbSe₂. HRTEM images show that theinterface bonding of the sintered composite is enhanced. The diffusion of Cu atoms fromCu matrix to NbSe₂was also detected. Interfacial reaction between Cu and NbSe₂andlimited precipitation of Cu2Se at the interface were determined by the selected areaelectron direction pattern（SADP）.