Effects Of Au(In?Sn) On Microstructure And Properties Of Ag-20Cu-2Ni Alloy

AgCuNi alloy is widely used in the field of low load electrical contact materials.Because of it has stable electrical contact properties,low material transfer loss,and it has low and stable resistivity,low segregation,It is also not easy to soften the material due to aging.However,AgCuNi alloy material has some problems in the actual engineering application process,such as low strength,low hardness,poor resistance to vulcanization,poor corrosion resistance and short service life.Based on Ag-20Cu-2Ni,the Ag-15Cu-10Au-2M(M=Ni,In,Sn)alloy was designed and prepared by the addition of alloying elements Au,In and Sn in this paper.Its structure and properties were studied systematically,and provide theoretical and technical basis for the development of silver-based electrical contact materials with excellent performance.In this paper,four alloys of Ag-20Cu-2Ni and Ag-15Cu-10Au-2M(M=Ni,In,Sn)were prepared by vacuum induction melting.After homogenization treatment,the sheet was rolled and the wire was drawn.The samples were Characterized by means of metallographic microscope,XRD,DSC,SEM,EPMA,mechanical properties test,microhardness test,tensile fracture morphology observation after annealing process,vulcanization process.The effects of the addition of alloying elements on the microstructure and properties of the alloy under different process conditions were studied systematically.The following research results were obtained:(1)Ag-20Cu-2Ni alloy,Ag-15Cu-10Au-2M(M=Ni,Ln,Sn)alloys are composed of dark gray copper-rich phase and light silver rich phase.The Ni element is enriched in the copper-rich phase,which is almost undetectable in the silver-rich phase,and the Au,In,and Sn elements are uniformly distributed in the two-phase region.(2)The work hardening effect of Ag-15Cu-10Au-2M(M=Ni,In,Sn)alloy is remarkable.The sheet sample is deformed by rolling to 95%deformation,and the hardness reaches 201HV,210HV,214HV,respectively.Compared with the 95%deformation Ag,20Cu-2Ni alloy which hardness is 167HV,the hardness of Ag-15Cu-10Au-2M(M=Ni,In,Sn)alloys is increased by 20.4%,25.7%and 28.1%,respectively.(3)The tensile strength of the processed Ag-15Cu-10Au-2M(M=Ni,In,Sn)alloys reached 744MPa,764MPa,and 851MPa,respectively.Compared with the tensile strength of the Ag-20Cu-2Ni alloy which tensile strength is 661 MPa,the tensile strength is increased by 83MPa,103MPa,and 190MPa,respectively,with an increase of 12.6%,15.7%and 28.7%.(4)The addition of Au,In and Sn elements significantly improves the strength and hardness of the alloy,while the alloy still has good plasticity,the elongation of the fully annealed sample Ag-15Cu-10Au-2M(M=Ni?In?Sn)alloy is 31.8%,24.64%,and 27.62%,respectively.(5)After the deformation of the alloy reaches 95%,the microstructure is fibrous,and the fiber structure is parallel to the drawing direction.After annealing and softening treatment,the recrystallized texture still retains the deformation texture,and the recrystallized grains are fine.It is very advantageous to significantly improve the mechanical properties such as hardness and strength of the alloy.(6)The addition of Au,In,and Sn elements increases the electrical resistivity of the alloy,but still maintains good electrical conductivity,while at the same time significantly improving the sulfur resistance of the alloy.