Effect Of Rare Earth Element Ce On The Microstructure And Properties Of Cu-10Ni-7Si-5Mn Alloy

Due to their excellent corrosion resistance,wear resistance,and thermal conductivity,Cu-Ni-Si series alloys are widely used in various fields,such as bushings,seawater desalination pipelines,condensers,heat exchangers etc..However,as the environmental conditions become demanding,the service life of the components mentioned above is facing severe challenges.Rare earth modification is currently a hot topic,but its effect on the structure and properties of Cu-Ni-Si alloys is still a challenging issue.In the present study,therefore,taking Cu-10Ni-7Si-5Mn-xCe alloy with different Ce content as targets,through using some technical measurements,such as the optical microscope,scanning electron microscope,transmission electron microscope,X-ray diffraction,Brinell hardness,abrasive wear test,electrochemistry,XPS and other experimental tests,We studied the influence of varying Ce contents,extrusion ratio and aging treatment on Cu-10Ni-7Si-5Mn-xCe alloy's structure,hardness,wear resistance,and 3.5%Na Cl corrosion resistance.The effects of rare earth content and extrusion ratio on the microstructure evolution,wear resistance and corrosion resistance of Cu-10Ni-7Si-5Mn-XCe alloy were discussed emphatically.(1)The results of structure and phase analysis show that with the increase of Ce content,the degree of refinement of?Cu(Ni,Si,Mn)and Mn₁₂Ni_4.04Si_2.84 phases in Cu-10Ni-7Si-5Mn-xCe alloy increases firstily,and then decrease;as the increase of extrusion ratio,the degree of refinement of the?Cu(Ni,Si,Mn),Ni₃Si,Cu_0.73Ni_0.06Si_0.21,Mn₁₂Ni_4.04Si_2.84gradually increases.The rare-earth-containing phase of Cu-10Ni-7Si-5Mn-xCe alloy is the CuCe phase,and the size is reduced from 3?m in its as-cast state to 1?m in the extruded state.The CuCe phase and the matrix form a semi-coherent interface,which plays a role in refining the alloy structure.(2)The wear test results show that the Cu-10Ni-7Si-5Mn-0.1Ce alloy with a rare earth Ce content of 0.1%,an extrusion ratio of 6.25,and a solid solution at 825°C for2 hours and then aging at 450°C for 3 hours has the smallest removal amount of wear0.36 g.Compared with Cu-10Ni-7Si-5Mn without Ce,the hardness of Ni₃Si phase increases by 138 Hv and the phase proportion increases by 18%.In the extruded state,the overall hardness of the three phase of Ni₃Si,Cu_0.73Ni_0.06Si_0.21 and Mn₁₂Ni_4.04Si_2.84increases by 326 Hv,and the phase ratio increases by 7%.These phases play an anti-wear role in the abrasive wear process of the alloy.(3)The corrosion resistance of the alloy with 0.1%Ce content is the best.Excessive content of Ce would increase the reaction numbers of the micro cell corrosion,thereby reducing the corrosion resistance of the alloy.Rare earth Ce exists in the corrosion layer in the form of its oxides Ce₂O₃ and CeO₂ that increase the impedance of the corrosion product film and allow the open circuit potential move to the positive direction,thereby improving the corrosion resistance performance of the Cu-10Ni-7Si-5Mn-xCe alloy.In the early stage of corrosion,because the extrusion ratio delays the reaction between anode and cathode by refining the grains,the corrosion resistance of the alloy increases with the increase of the extrusion ratio.While in the later stage,due to the growth of the corrosion product film,the difference of corrosion resistance decreases regardless of different extrusion ratio.The developed Cu-10Ni-7Si-5Mn-xCe alloy was compared with Cu-10Ni-7Si-5Mn alloy?45#steel and ZQSn5-5-5 tin bronze in abrasive wear and corrosion resistance.It finds that adding Ce element up to 0.1%,under the same conditions,the wear resistance of Cu-10Ni-7Si-5Mn-0.1Ce,which is little less than that of 45#steel,is superior to Cu-10Ni-7Si-5Mn alloy and ZQSn5-5-5 tin bronze,especially the corrosion resistance of it is better than Cu-10Ni-7Si-5Mn alloy,45#steel,and ZQSn5-5-5 tin bronze.