( 1. 北京工业大学 固体微结构与性能研究所， 北京 100022;
2. 中南大学 材料科学与工程学院， 长沙 100083)
摘 要: 采用硬度测试、 金相观察、 扫描电镜和透射电镜测试及能谱分析的方法， 研究了稀土元素Sc含量对Al-4Cu合金组织的影响。 结果表明： Sc可显著细化Al-Cu合金的网胞组织， 减小枝晶间距， 细化合金的晶粒组织，提高合金的显微硬度， 提高幅度最约70%； 将Sc添加到Al-4Cu合金中， 当w(Sc)≈0.3%时， Sc除部分固溶于基体外， 大部分与Al形成Al-3Sc相, 其与基体的共格或半共格界面促进了θ′(CuAl2)的析出； 当w(Sc)>0.3%时， Sc除部分固溶和形成Al3Sc外， 还与Al、 Cu元素作用形成W(AlCuSc)相，降低Cu在α(Al)中的固溶度， 减少Al2Cu(θ′)相的生成， 从而降低了合金的性能。
关键字: 稀土; 钪; 显微组织; Al-Cu合金; 细化作用
containing scandium
（ 1. Institute of Microstructure and Property of Advanced Materials,
Beijing University of Technology, Beijing 100022, China;
2. School of Materials Science and Engineering,
Central South University, Changsha 410083, China）
Abstract: The effects of different contents of rare earth Sc on the microstructures of Al-4Cu alloy by means of hardness measurement, optical microscopy(OM), scanning electron microscopy(SEM), transmitting electron microscopy(TEM) and energy spectrum analysis. The results show that the network structures of Al-Cu alloys can be remarkably refined, the distance of dendritic structure decreases, the structure of the alloy can be refined and the micro-hardness can be enhanced 70% or so. With additions of trace Sc to Al-Cu alloy, when the mass fraction of Sc is not more than 0.3%, Sc mostly， besides of a part of Sc existing in α(Al) solid solution， forms Al3Sc phase with Al. When the amount is up to 0.5%, apart from the above-mentioned, Sc can interact with Al and Cu to form W(AlCuSc) phase， resulting in decrement of solid solubility of Cu in α(Al) solid solution and the amount of CuAl2(θ′) phases, reducing the properties of alloy.
Key words: rare earth; scandium; microstructure; Al-Cu alloy; refinement
