Study On Structure And Properties Of Ag-15Cu-10Pd-2X(Ni?In Sn) Alloy

As a silver-based electrical contact material,it is required to have excellent properties,such as high hardness,high strength,low electrical resistance and good resistance to vulcanization.At present,Ag-Cu-Ni alloy has overcome the shortcomings of Ag-Cu and Ag-Ni alloys,but its hardness is still not high and its resistance to vulcanization is poor.In this paper,Ag-15Cu-10Pd-2X(Ni,In,Sn)alloy was prepared.In this paper,Ag-20Cu-2Ni,Ag-15Cu-10Pd-2Ni,Ag-15Cu-10Pd-2In and Ag-15Cu-10Pd-2Sn alloys were prepared by high vacuum induction melting.The microstructure,hardness,electrical resistivity,tensile strength,elongation,fracture morphology and resistance to vulcanization of the alloy were investigated by SEM,microhardness tester,resistance tester,EPMA,XRD,TEM and DSC.The results of the study are as follows:1.The phase composition of the four alloys is multiphase.In the Ag-20Cu-2Ni alloy,there are Ag-rich phase,Cu-rich phase and Ni-aggregate phase.In the Ag-15Cu-10Pd-2Ni alloy,there are Ag-rich phase with a small amount of Pd,Cu-Pd-Ni phase and Ni-aggregate phase.In the Ag-15Cu-10Pd-2In alloy,there are Ag-rich phase containing Pd and Cu-Pd-Ag phase.In the Ag-15Cu-10Pd-2Sn alloy,there are Ag-rich phase,Cu-Ag-Pd phase,Pd-Sn phase and Cu-Ag phase.2.After rolling and drawing,the microstructure of the alloy generally shows the fibrous structure.According to BXRD and EPMA analysis,the gray phase is Ag-rish phase,the dark gray is Cu-rich phase,the Ni element is mainly existing in Cu-rich phase.Small granular In3Pd2 phase appeared in Ag-15Cu-10Pd-2In alloy,and large granular and small granular Pd2Sn phase appeared in Ag-15Cu-10Pd-2Sn alloy.3.The hardness of Ag-20Cu-2Ni,Ag-15Cu-10Pd-2X(Ni,In,Sn)alloy after processing increase significantly.When the deformation reaches 95%,the hardness of the alloy is obviously increased,reaching 167 HV,197 HV,211 HV,203 HV,respectively,which is higher than the initial value 107%,70%,61%.The tensile strength of the alloy with the tensile deformation of 95.4%reached 660.842 MPa,793.187 MPa,800.346 MPa,and 796.295 MPa,respectively,and the corresponding elongations were 1.24%,2.74%,1.48%,and 1.57%,respectively.The hardness of the alloys is obviously improved after adding the Pd element.4.After annealing at different temperatures(250?,350 ?,450?,550 ?,650 ?)for 1 h,the hardness and strength of alloys is decreasing,the resistivity decreases first and then increases slowly,and the elongation increases with the temperature increase.The tensile strengths of Ag-20Cu-2Ni,Ag-15Cu-10Pd-2Ni,Ag-15Cu-10Pd-2In and Ag-15Cu-10Pd-2Sn alloys after annealing at 550? reached 299.515 MPa,399.965 MPa and 422.038 MPa,respectively.The elongations were 22.05%,21.16%,16.68%,and 12,82%,respectively.The tensile fracture appearance of both machined and annealed specimens belongs to ductile fracture.5.The resistance to vulcanization of Ag-15Cu-10Pd-2Ni,Ag-15Cu-10Pd-2In and Ag-15Cu-10Pd-2Sn alloys is better than Ag-20Cu-2Ni alloy.6.The Ag-15Cu-10Pd-2In alloy has the highest hardness,the lowest resistivity and excellent anti-vulcanization property.