退火对冷拉拔Al-0.7Fe-0.2Cu合金组织性能的影响

Effect of Annealing on Microstructure and Mechanical Properties of Cold Drawn Al-0.7Fe-0.2Cu Alloy

运用光学显微镜、扫描电镜和透射电镜研究了冷拉拔铝合金Al-0.7Fe-0.2Cu在不同退火处理制度下的微观组织结构演变,并分析了其对电导率和力学性能的影响。结果表明:300℃退火,初生相Al(Fe,Cu)中Cu元素部分回溶于基体,500℃退火,Cu元素几乎完全回溶于基体;冷拉拔Al-0.7Fe-0.2Cu丝材再结晶温度为300～350℃;450℃长时间退火后,再结晶晶粒长大不明显,但有极少量的晶粒出现异常长大现象,这主要是因为Al(Fe,Cu)相分布不均匀对晶粒长大的影响;其电导率在250℃×2h条件下退火达到最大值;超过350℃长时间退火其抗拉强度趋于稳定,伸长率降低。冷拉拔合金在350℃×2h退火处理制度下,拥有最优异的导电性能和力学性能。

The microstructure evolution of cold-drawn aluminum alloy A1-0.7Fe-0.2Cu under different annealing conditions was investigated with OM, SEM and TEM. Electrical conductivity and tensile testing of annealed specimens were performed to examine the effect of annealing condition and microstmcture on the conductivity and mechanical properties. The results show that partial Cu element in primary phase A1 （Fe, Cu） has dissolved in A1 matrix after annealing at 300 ℃, and nearly all the Cu element dissolves in A1 matrix when the alloy is treated at 500 ℃. The recrystallization temperature of the cold drawn A1-0.7Fe-0.2Cu wire is 300-350 ℃. Recrystallization grain growth is not obvious after annealing at 450℃ for long time, but there is an abnormal growth of a little amount of grains, the reason is that the A1 （Fe, Cu） phase are not uniformly distributed the grain boundary and the particles can prevent A1 grain from growing up. The electrical conductivity attains a maximum at annealing condition of about 250℃ ×2 h. No change in tensile strength is observed with further annealing above 350 ℃, and meantime, the elongation decreases. The cold drawn A1-0.7Fe-0.2Cu wire reaches the best electrical conductivity and tensile properties after annealing at 350℃ for 2 h.