Surface Modification Studying Of CuCr25Alloy By High Current Pulses Electron Beam

CuCr alloy with high content of Cr has been widely used in the preparation ofvacuum circuit breaker, large-scale integrated circuit lead frame materials, trams,overhead conductor of electric locomotive and electrical equipment. The binary phasediagram of Cu-Cr shows low solubility of Cr in copper,especially almost no solution atlow temperatures. Cu and Cr will be separated with conventional casting, which isunable to prepare CuCr alloy with excellent performance. Rapid solidification, powdermetallurgy or other preparation method is adopted currently. There will be a certaindegree of concentration and segregation in the process of preparing CuCr alloy withhigh Cr content,gathering particles and distributed inhomogenously, thus bringing thedeterioration performance of local material, which will easily lead to failure ofmaterial surface.Thereby causing the failure of the whole. Therefore, improving thesurface properties by studying surface composition and surface properties of CuCr alloyhas become a tendency. The following research has been carried out in order to specifythe mechanism of surface modification of CuCr alloy under different treatmentconditions:（1）High current pulsed electron beams with different process parameters wereapplied on the surface of CuCr25alloy after preparing CuCr25alloy in a vacuuminduction melting furnace.Micro-cracks,millipore and other typical characteristics ofelectron beam modification emerged on the surface of the alloy.Cr-enriched phase onthe surface slowly being submerged by the Cr-enriched phase with the increasingfrequency of bombardment.Spherical Cr produced by liquid phase separation occurredsimultaneously on Cu.After electron beam surface remelting of CuCr25alloy,conductivity of alloy surface has been slightly decreased, while corrosion resistance andwear resistance performance of alloy surface have been significantly improved.（2）Magnetic controlled sputtering method was applied to coatAl on the surface ofCuCr25alloy, then surface alloyed after coating with high current pulsed electronbeams. Cracks and volcano craters appeared after surface alloying.Meanwhile, newphases AlCu4,Al2Cu3,and Al2Cr are generated,refined the surface structure. Thecorrosion resistance and wear resistance performance were appropriately increasedwithout decreasing the electrical conductivity of material surface. （3）Magnetic controlled sputtering method was applied to coat Zr on the surface ofCuCr25alloy, then surface alloyed after coating with high current pulsed electronbeams. New phases ZrCu、ZCur3and Cr2Zr has generated,and the surface structure wasrefined.After coating Zr on CuCr25surface, the electrical conductivity of materialsurface decreased slightly,but both the corrosion resistance and wear resistanceperformance have been significantly improved.（4）Magnetic controlled sputtering method was applied to coat Nb on the surfaceof CuCr25alloy, then surface alloyed after coating with high current pulsed electronbeams. Part of Nb film on the surface generated a new phase Cr2Nb with Cr afterirradiating by electron beam, and other parts distributed in Cu substrate. After coatingNb on CuCr25surface, the electrical conductivity of material surface decreasedslightly,but both the corrosion resistance and wear resistance performance have beensignificantly improved.（5）Magnetic controlled sputtering method was applied to coat Cr film on thesurface of CuCr25alloy, then surface alloyed after coating with high current pulsedelectron beams. Part of Cr film on the surface solid-soluted in Cu substrate afterirradiating by electron beam, and other parts which spherical or particles shaped diffusedistributed in alloy due to liquid phase separation,decreasing the surface conductiveperformance slightly, but corrosion resistance and wear resistance performance of alloysurface has been significantly improved.