( 1. 北京工業(yè)大學 固體微結(jié)構(gòu)與性能研究所， 北京 100022;
2. 中南大學 材料科學與工程學院， 長沙 100083)
摘 要: 采用硬度測試、 金相觀察、 掃描電鏡和透射電鏡測試及能譜分析的方法， 研究了稀土元素Sc含量對Al-4Cu合金組織的影響。 結(jié)果表明： Sc可顯著細化Al-Cu合金的網(wǎng)胞組織， 減小枝晶間距， 細化合金的晶粒組織，提高合金的顯微硬度， 提高幅度最約70%； 將Sc添加到Al-4Cu合金中， 當w(Sc)≈0.3%時， Sc除部分固溶于基體外， 大部分與Al形成Al-3Sc相, 其與基體的共格或半共格界面促進了θ′(CuAl2)的析出； 當w(Sc)>0.3%時， Sc除部分固溶和形成Al3Sc外， 還與Al、 Cu元素作用形成W(AlCuSc)相，降低Cu在α(Al)中的固溶度， 減少Al2Cu(θ′)相的生成， 從而降低了合金的性能。
關(guān)鍵字: 稀土; 鈧; 顯微組織; Al-Cu合金; 細化作用
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
