研究了在250~470 ℃下感应加热连续退火对冷拉拔铜包铝复合线材包覆Cu层和Al芯组织、界面层金属间化合物组成和厚度的影响, 并与传统炉式等温退火的实验结果进行了比较. 结果表明: 当感应加热温度为250 ℃时, Cu层和Al芯只发生回复现象; Cu层和Al芯分别在300和330 ℃时开始发生再结晶, 在430 ℃时均发生完全再结晶, 平均晶粒尺寸分别约为6.0和7.3 μm. 当温度为360 ℃时, Cu/Al界面形成了不连续分布的CuAl₂金属间化合物; 当温度为390 ℃时, 界面形成了连续分布的CuAl₂层, 430 ℃时形成了CuAl₂和Cu₉Al₄ 2种化合物层, 平均厚度分别约为0.52和0.48 μm. 进一步升高温度, Cu层和Al芯的晶粒明显长大, 界面化合物层厚度呈增大趋势. 在本工作实验条件下, 冷拉拔铜包铝复合线材合理的感应加热连续退火温度为430 ℃. 与炉式等温退火工艺相比, 感应加热连续退火方法可明显细化铜包铝复合线材Cu层和Al芯的再结晶晶粒, 显著减小界面金属间化合物层厚度.

Influences of induction heating continuous annealing (IHCA) on the microstructure of both copper sheath and aluminum core, and intermetallic compound at the Cu/Al interface of cold-drawn copper-clad aluminum wire were investigated, compared with the traditional isothermal annealing in furnace (TIA). The results showed that recovery of both the copper sheath and aluminum core happened when the temperature of IHCA was 250 ℃. Recrystallization began to occur in the copper sheath at 300 ℃ and in the aluminum core at 330 ℃, respectively. Complete recrystallization of both the copper sheath and aluminum core took place at 430 ℃, whose average grain size were 6.0 and 7.3 μm, respectively. An intermetallic compound CuAl₂ discontinuously formed at the interface at 360 ℃, and continuous CuAl₂ layer formed at 390 ℃. Both CuAl₂ layer and Cu₉Al₄ layer formed at the interface at 430 ℃, with average thickness of 0.52 and 0.48 μm, respectively. With further raising the temperature, the grains of both copper sheath and aluminum core grew, and the thickness of the intermetallic compound layer increased slightly. The appropriate IHCA temperature of the cold-drawn copper-clad aluminum wire was 430 ℃. Compared with TIA, IHCA was able to not only refine recrystallized grain of both copper sheath and aluminum core remarkably, but also reduce the thickness of the interfacial intermetallic compound layer in the copper-clad aluminum wire.