亚微米晶Cu-5%Cr冷拉拔后的回复再结晶及热稳定性

Recovery,Recrystallization and Thermal Stability of Submicron Crystalline Cu-5%Cr after Cold Drawing

通过对冷拉拔的亚微米晶Cu-5%Cr丝材进行退火及高温热处理,研究其回复与再结晶、组织与性能的变化及其热稳定性。采用透射电镜(TEM)分析了退火后Cu-5%Cr的组织结构,并对其进行了硬度和导电性的测试。结果表明,冷拉拔的亚微米晶Cu-5%Cr丝材退火处理时析出大量的Cr相颗粒,Cu基体发生了回复和再结晶,其再结晶温度是在480℃～560℃范围内,其导电率在退火温度为550℃左右出现峰值。冷拉拔的亚微米晶Cu-5%Cr丝材在600℃以上热处理,硬度趋于稳定,其组织也比较稳定。在800℃热处理时,Cu晶粒虽有所长大,但其晶粒尺寸仍保持在500 nm～600 nm。这主要是因为Cr相颗粒有阻碍Cu晶粒长大的作用。同时发现,拉拔变形量大的在热处理时再结晶形核数量多,晶粒更细小。

Through annealing and high temperature treatment, the recovery and recrystallization, the variations of microstructures and properties, and the thermal stability of submicron crystalline Cu-5%Cr wires after cold drawing have been investigated. The microstructures of as annealed Cu-5%Cr wires were characterized by TEM, and the hardness and electrical conductivity of them were also tested. The results show that, lots of Cr particles precipitate from the cold drawn Cu-5%Cr wires while being annealed, and meantime, recovery and recrystallization occur in Cu matrix. The recrystallization temperature of the cold drawn Cu-5%Cr wires is in the ranger of 480℃～560℃. The electrical conductivity attains a maximum at annealing temperature of about 550 ℃. While being heat treated above 600 ℃, the hardness of the cold drawn Cu-5%Cr wires tends to be stable. The microstructure is also relatively stable. When it is heat treated at 800 ℃, the grain size of Cu increases in some extent, but it remains in 500～600 nm. The reason is that Cr particles can prevent Cu grains from growing up. Furthermore, it is noted that, the higher drawing deformation leads to higher ratio of recrystal nucleation during recrystallization, and finer recrystal grains.