| Owing to the combination of high strength and high conductivity,copper matrix composite,showing better prospects,is expected to be applied in various fieles,such as space industry,railway contact wires,micro-electronic and so on.With the increase of service requirement,it is necessy to explore the new fabricating method to obtain copper matrix composites with better properties.In this paper,the Cu-Cr-Zr alloy was prepared by hot pressing,the effects of different heat treatments on the microstructure and properties were researched.At the same time,the full dense Cu-SiC composite was prepared by electro-deposition and hot isostatic pressing,the effects of content of SiC particles in electroplate liquid on the structure and properties of Cu-SiC composite was studied.For Cu-Cr-Zr alloy,the relationship between time,temperature of solution and aging on structure,properties of the alloy was studied.It can be easily found:The hardness of Cu-Cr-Zr alloy increased with increase of soluted temperature firstly,then decreased because of the combined action of grain size and solubility.Owing to the precipitation strengthening,with the prolongation of aging time,the hardness increased firstly,after reaching the peak hardness,the growth of the precipitates caused the decrease of hardness,leading to the overaging.The hardness of Cu-Cr-Zr alloy soluted at 960? for 1 h then aged at 450? for 4 h was highest,about 141 Hv.The conductivity of the Cu-Cr-Zr alloy increased rapidly with the prolongation of aging time and then maintained stable.The Cu-Cr-Zr alloy soluted at 960? for 1 h then aged at 450? for 4 h was analysed by TEM,it can be found that the precipitates were Cr phase and Cu5Zr phase.The increase of strength was caused by the existence of precipitates,the tensile strength of the Cu-Cr-Zr alloy aged at 450? for 4 h increased widely,was about 397 MPa.Also it was determined that the effect of Cr particles on strength was more important than that of Cu5Zr particles.A large number of rounded dimples,which are indicators of cavities formed through precipitates/Cu decohesion and perhaps debonding at the prior inter-particle boundaries,can be found on the fracture surface of tensile tested specimens,showing excellent plasticity.According to the Matthissen-Fuliminge rule,the function between time and volume fraction of precipitates can be founded:.For the Cu-SiC composites,the composite was prepared by electrodeposition and hot isostatic pressing.The effects of content of SiC particles in electroplate liquid on the structure and properties of Cu-SiC composite were studied.It can be found:as the content of SiC particles increased,the nanoparticles in composites continued to increase untile reaching a maxium,at the same time,owing to SiC particles in the matrix pinning the crystal boundary,the grain size of the Cu matrix decreased.Two sizes of SiC in composite can be found using TEM and SEM,one is the sub-micron SiC particles caused by assembly and growth of SiC,which was found on grain boundary of the matrix,the other is the nano-size SiC particles.Also the boundary between Cu and the second phase is smooth,no interfacial reaction can be found.The more SiC particles in composites,the higher hardness of composites is.As the content of SiC particles in electroplate liquid is 6g/L,the content of SiC particles in composites were maximum,about 3.0 vol%,the grain size of Cu matrix is smallest,about 15um,and the hardness is highest,about 72.7Hv.According to friction experiment,with the increase of SiC particles in composites,the weight loss of Cu-SiC composite decreased.Owing to the high hardness of SiC,the friction pair was deformable,the width of grindingcrack became large.It can be found that the wear mode was adhesive wear and oxidative wear on the worn surface. |
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