Fe/Si比对稀土处理工业纯铝组织性能的影响

通过添加Si改变稀土处理工业纯铝的Fe/Si比,采用金相显微镜、扫描电镜、电子探针、室温拉伸试验和电导率测试研究了Fe/Si比对稀土处理工业纯铝显微组织、屈服强度以及导电率的影响。结果表明: 随着Fe/Si比增大,铸态合金的屈服强度总体呈下降趋势,导电率逐渐上升; 当Fe/Si比不大于1.00时,晶粒尺寸较小,合金强度较高,导电率较低; 当Fe/Si比大于1.00时,晶粒粗大,合金强度降低,导电率提高; Fe元素主要在晶界和晶内第二相中聚集分布,Si元素呈点状均匀分布,稀土元素容易在第二相上聚集。根据Fe/Si比-强度-导电率性能曲线,可通过添加Si改变工业纯铝的Fe/Si比,实现铝材屈服强度、导电率的良好匹配。

Effect of Fe/Si Ratio on Microstructure and Properties of Commercially Pure Aluminum Treated by Rare Earth

The Fe/Si ratio of commercially pure aluminum treated by rare earth was changed by an addition of Si, and the effect of low Fe/Si ratio on its microstructure, yield strength and conductivity was investigated by using metallographic microscope, scanning electron microscope, electron probe microanalyzer, room temperature tensile test and electrical conductivity test. Results show that with the increase of Fe/Si ratio, the yield strength of the as-cast alloy generally decreases and the electrical conductivity gradually rises. When the Fe/Si ratio is not greater than 1.00, the alloy is in smaller grain size, with higher strength and lower conductivity; when the Fe/Si ratio is greater than 1.00, the alloy is in coarser crystal grains size, with the strength reduced, but the electrical conductivity improved. It is found that in the alloy, Fe is mainly distributed in the second phase at grain boundaries and within grains, while Si is uniformly distributed in dots and rare earth is easy to accumulate on the second phase. According to the curves of strength and conductivity performance to Fe/Si ratio, the Fe/Si ratio of commercially pure aluminum can be changed by an addition of Si, so as to achieve a good match of aluminum yield strength with conductivity.