Ag含量对纤维相强化Cu-Ag合金组织及性能的影响

EFFECTS OF Ag CONTENT ON MICROSTRUCTURE AND PROPERTIES OF THE FILAMENT STRENGTHENED Cu-Ag ALLOYS

通过冷拉拔结合中间热处理制备了不同Ag含量的纤维相强化Cu-Ag合金。研究了Ag含量对合金组织形态、强度和电导率的影响．Ag含量在6%—24%范围内的合金铸态组织包含初生α枝晶、共晶体和次生相．在拉拔过程中,共晶体及次生相均演变成细密的纤维形态．随Ag含量的升高,共晶体及次生相数量增多,合金强度及应变硬化速率升高,电导率下降．尤其当Ag含量增加使合金组织中的共晶纤维束增多并呈连续网状分布时,电导率下降更为明显,高Ag含量合金中共晶体纤维束的强化效应明显高于低Ag含量合金中次生相纤维的强化效应,但其对合金导电性能的损害程度也高于后者．

Cu-Ag filamentary microcomposites with various Ag concentrations were prepared by cold drawing combined with intermediate heat treatments. The influences of Ag content on the microstructure evolution, tensile strength and electrical conductivity were investigated. The as-cast microcomposites containing 6%-24% Ag （mass fraction） consisted of α-Cu dendrites, eutectic colonies and secondary particles. The eutectic colonies and secondary particles evolved into eutectic filamentary bundles and uniformed fine fibres during cold drawing. With the increase of Ag content, the tensile strength and strain hardening rate increase but the electrical conductivity decreases because the amount of the eutectic filamentary bundles and secondary precipitated fibres increases in the microcomposites. In special, the electrical conductivity loses more significantly if the Ag concentration is high enough to produce the eutectic filamentary bundles with a continuous net-like distribution. The eutectic filamentary bundles in the microcomposites with high Ag concentrations can produce greater benefit to the material strengthening than the secondary precipitated fibres in those with low Ag concentrations. However, the eutectic filamentary bundles can reduce the electrical conductivity more evidently than the secondary precipitated fibres.