Research On The Preparation And Interface Properties Of Copper-steel Coated Composite Material

The copper-steel coated composite material is a kind of composite materials,because of the two components,its strength and toughness are as high as steel,on the other hand,it has a good electrical conductivity and corrosion resistance just as copper,what's more,the copper-steel coated composite material will have some new characters which are different from the two raw material,the new character was caused by the recombination and interaction of the two parts.However the preparation is imperfect,especially the theory of interfacial bonding is unsure,the copper-steel coated composite material won't be widely used until the above problems were solved,the preparation and properties were studyed in this experiment so as to find the solution.The pure T2 copper,QA19-4 aluminum bronze,45-steel and 304-stainless steel were chosen as the raw materials,the copper-steel coated composite material were prepared by vacuum high temperature process and atmosphere fused cast process in the graphite mould,then the microstructure,mechanical properties,interface element were studied,by means of these work we had a good exploration of the interfacial bonding between the two metals.It showed that:1.The copper-steel coated composite material can be better prepared by vacuum high temperature process and atmosphere fused cast process,in which the sintering temperature is 1150? and kept for 90min,whereas the vacuum degree was 10-2?10-3Pa.As we can see the microstructure was reasonable distributed,the interface was distinct without the pore and impurities,and it showed some risehighs which had ligulate and serrate shap,besides there was a transition region with element diffusion in it.2.The copper-steel composite material had a high interfacial bonding strength,its tensile strength and shear strength were higher than T2-copper and copper alloy.The fracture surface of the tensile specimen appeared in T2-copper or copper alloy part,whereas the fracture of shear specimen appeared in the copper-steel interface.The shape of ductile fracture in the T2-copper/steel specimen was dimple fracture,but the shape of quasi-cleavage fracture in the steel-QA19-4 specimen was dimple fracture with dimple fracture and brittle fracture,both of them had a typical plasticity.3.The transition layer's width of the copper steel composite materials was slightly changed when the component was different.The width of the transition layer was range of 40?200?m,the more alloying element in the base material the wider width the transition layer was.The microhardness values of transition layer was higher than the parts of the base material.4.The interface bonded with three kinds of form,that were fused form,surface diffusion and grain boundary penetration,under the high temperature and vacuum conditions,the copper liquid spreading dispersed along the surface of solid steel,then the two parts fused together.There was a concentration gradient in the interface caused by the different alloying element between the two sides,so the contained respective elements would diffuse from high concentration areas to the low concentration areas.The liquid metal atoms preferentially dispersed along the grain boundary and would form a concentration gradient with the crystal atoms in the diffusion process,moreover there would be a grain boundary diffusion zone due to the diffusion of atoms.Surface diffusion and grain boundary diffusion were the main factors for the formation of the transition zone.