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采用连续铸造技术制备Ag-28Cu-0.75Ni(%,原子分数)合金棒材,真空退火后进行冷拉拔加工,分别采用X射线衍射(XRD)、金相显微镜(OM)和扫描电镜(SEM)对合金的物相、铸态、加工态和断口组织进行表征,并对导电率、硬度、强度和延伸率进行测试。结果表明:Ag-28Cu-0.75Ni的显微组织为:以Ag,Ni为溶质的Cu相固溶体,以Cu为溶质的Ag相固溶体和共晶(Ag+Cu)结构;其连铸态微观结构为典型的表面细晶区、柱状晶区和中心等轴层片状晶区三区结构,铸锭中散落着形貌清晰、形态规整的枝晶,枝晶偏析以及中心等轴区的边界偏析造成易腐蚀的低熔点区域。同时,材料本身加工态横截面晶粒细化、组织均匀,纵截面晶粒由点块状变为纤维状,发生择优取向形成形变织构。随真应变的增加,强度、硬度随之增加,而导电率、延伸率下降。
Ag-28Cu-0.75Ni (%, atomic fraction) alloy bar was prepared by continuous casting technique and cold-drawn after vacuum annealing. XRD, OM and SEM ) Phase, as-cast, as-machined and as-ruptured microstructures were characterized and tested for electrical conductivity, hardness, strength and elongation. The results show that the microstructure of Ag-28Cu-0.75Ni is Cu-Ag solid solution and Cu-solid Ag solid solution and eutectic (Ag + Cu) It is a typical three-zone structure of fine grain region, columnar grain region and central equiaxed lamellar grain region. The ingots are scattered with dendrites, dendrite segregation and boundary segregation Caused by corrosion of the low melting point area. At the same time, the material itself processed grain cross-section grain refinement, uniform organization, the longitudinal section of the grain into a fibrous block by the point, the occurrence of preferential orientation to form deformation texture. With the true strain increases, the strength and hardness increase, while the conductivity, elongation decreased.