含稀土Er的Al-Zn-Mg合金的组织与性能

为了探讨稀土Er对热处理可强化(沉淀强化)的铝合金系作用,采用铸锭冶金法制备了6种含Er量不同的Al-Zn-Mg合金进行了深入分析.通过硬度测试、拉伸力学性能测试、金相观察、X射线衍射和扫描电镜观察,研究了稀土元素Er对Al-Zn-Mg合金显微组织和力学性能的影响.实验结果表明,稀土元素Er可以显著地细化Al-Zn-Mg合金的铸态晶粒,减小其枝晶网胞,当Er的添加量达到w(Er)=0.7％时,枝晶网胞几乎完全消失,晶粒变得非常细小且分布均匀;对于合金的冷轧态组织以及时效态晶粒也有同样的细化效果;添加Er后,Al-Zn-Mg合金在冷轧态及时效态下的屈服强度(σ0.2)及抗拉强度(σh)都得到了显著的提高,但塑性有所降低;稀土元素Er添加到Al-Zn-Mg合金中,主要与Al相互作用形成了Al3Er相.合金显微组织的细化及合金的强化都与该相的形成和析出有关.

Microstructure and Properties of Al-Zn-Mg Alloys Containing RE Er

To indicate the microalloy effect of the rare earth element-Er on the alloys which could be strengthened by thermal treatment (precipitation consolidation, by ingot metallurgy six different compositions of Al-Zn-Mg alloys containing rare earth element Er were prepared and studied. The effects of Er on the microstructures and properties of Al-Zn-Mg alloys were studied through hardness test, tensile properties measurement, optical microscopy, X-ray diffraction analysis(XRD), scanning electron microscopy (SEM) and energy spectrum analysis. Experimental results show that the cast microstructures of Al-Zn-Mg alloys can be remarkably refined, and the dentrite structures eliminated, too. When the content of Er is up to w (Er)=0.7%, the dentrite structures of the alloy almost disappear, and the grains become very fine and equably distributed. As for the cool-rolled microstructure and the aged microstructure, the element Er has the same refining effects on them. The tensile strengh σb, and the yield strengh σ0.2 have been increased significantly after adding Er to them, but the elongations decrease a little. When adding Er to the Al-Zn-Mg alloy, element Er reacts with element Al to form the Al3Er phase. The refining of the microstructures and the strengthening of the alloy are relative to the formation and precipitation of the Al3Er phase.