退火处理对冷拉拔亚微米晶Cu-5wt%Cr合金组织与性能的影响

Effects of annealing process on microstructure and properties of cold drawn submicron crystalline Cu-5wt%Cr alloy wires

对冷拉拔的亚微米晶Cu-5wt%Cr合金丝材进行350～1000℃退火处理,用透射电镜分析了退火后合金回复与再结晶以及Cr相析出的变化,并测定合金硬度、强度、伸长率和电导率的变化。结果表明,冷拉拔的亚微米晶Cu-5wt%Cr丝材在450℃左右退火后析出大量Cr相颗粒,其再结晶软化温度为480～560℃。经550℃退火,得到了晶粒尺寸为200～300 nm的再结晶组织。其电导率在550℃左右退火时出现峰值。冷拉拔的亚微米晶Cu-5wt%Cr丝材在600℃以上退火,其组织和性能趋于稳定。经800℃高温退火,Cu基体晶粒长大到500～600 nm,仍保持在亚微米级。Cr相颗粒有阻碍Cu基体晶粒长大的作用,从而使亚微米晶Cu-5wt%Cr的组织和性能比较稳定。

Through annealing at 350 - 1000 ℃, the evolution of microstructure and properties of cold drawing submicron crystalline Cu-Swt% Cr wires resulted by recovery, recrystallization and Cr phase precipitation were investigated. The microstructure of as annealed Cu-Swt% Cr wires was characterized by transmission electron microscopy （TEM）, and the hardness, strength, elongation and electrical conductivity were also tested. The results show that lots of Cr particles are precipitated when the as drawn Cu-Swt% Cr wire is annealed at 450 ℃ or so, and the recrystallization softening temperatures of the as drawn Cu-Swt% Cr wire are in the range of 480 -560 ℃. When the as drawn Cu-Swt% Cr wire is annealed at 550 ℃, the recrystal grains with grain size of 200 - 300 nm are obtained. The electrical conductivity also attains a maximum at annealing temperature of about 550 ℃. When the as drawn Cu-Swt% Cr wire is annealed above 600 ℃ ,the microstructure and properties tend to be stable. When it is annealed at 800 ℃, the grain size of Cu matrix increases to 500 -600 nm, it still remains in submicron scale. The Cr particles can prevent the grains of Cu matrix from overgrowth,which leads the microstructure and properties of submicron crystalline Cu-Swt% Cr wire to be stable.