Investigation On Microstructure And Properties Of Ball Milled Cu-Fe Coating By Laser Cladding

As is known to all,High strength and high conductivity copper alloy as a function of structural material with excellent comprehensive physical and mechanical properties is widely used in electric power,machinery,electronics,defense and other areas.The Cu-Fe alloy has many favorable properties such as excellent conductive thermal conductivity,good ductility.But low strength and hardness,wear resistance had limited the wide application of Cu-Fe alloys.The liquid phase separation happens when the liquid C u-Fe alloy is solidificated to the liquid immiscibility gape.it will produce two different kinds of liquid phase: the C u-rich phase and Fe-rich phase.The traditional preparation method of Cu-Fe alloy easily generated from segregation(the effect of gravity),which limits its practical application value.Laser cladding technology,which has rapid solidification speed,can reduce reduce even inhibit the segregation organization during solidification of C u-Fe alloy.Thus laser cladding technology contributes to the preparation of high performance Cu-Fe alloy material.Secleting proper ratio of C u-Fe composition and milling cladding powder,can improve the liquid phase separation and reduce segregation organization during the solidification process.Prepare C u-Fe composite coating by the laser cladding with the ball milling C u-Fe powder.This paper mianly consider the effect of powder ratio,milling time,laser process parameters and substrate types to the coatings' macroscopic morphology,micro organization structure and properties.The main results as follows:laser cladding ball milling C u-Fe coating on medium carbon is easily formed under the laser parameter that follows: srectangular spot length is 5mm,the laser power is 1.5-2.5kw,the laser scanning speed is 6-12mm/s.The microstructure of Laser Cu-Fe coatings is mainly formed by Cu-rich matrix and Fe-rich spherical particles.Fe-rich spherical particle size is bigger as the destanse is close to the coating surface.But more segregation organization appears.Dispersion C u-rich particles phase generated from Fe-rich spherical particles due to second liquid phase separation induced by latent heat of crystallization.With the increase of Fe content between 5% and 12%,the Fe-rich globular particle size of the coating increases,and the same as segregation and porosity.The Fe-rich spherical particle size decreases as the milling time of cladding powder increases.The increase of laser power and the reduce of laser scanning speed will increase the Fe-rich globular particle size,the segregation organization and the occurrence of large porosities.By the same laser process parameters,with the increase of Fe content,conductivity and electrochemical corrosion resistance performance of C u-Fe coatings is reduced.Meanwhile the magnetic parameters decreases while the microhardness increased slightly.Compare to the coatings which prepared by 8 hours mllling powders,16 hours mllling powders coatings have lower conductivity,magnetic parameters and stronger corrosion resistance and microhardness.As laser line energy gradually increases between 150-250J/mm,the electrochemical corrosion resistance performance of the Cu-Fe coatings(same C u-Fe component content and milling time)decreased firstly and then increased,the electrical conductivity and saturation magnetization,remanence and coercivity are increased first and then decreased.