(1. 重慶大學(xué) 材料科學(xué)與工程學(xué)院，重慶 400044；
2. 重慶大學(xué) 電子顯微鏡中心，重慶 400044；
3. 包頭稀土研究院，包頭 014030)
摘 要: 采用金相顯微鏡(OM)、掃描電子顯微鏡(SEM)、透射電子顯微鏡(TEM)、X射線衍射儀(XRD)和差示掃描量熱法(DSC)等研究不同含量稀土Sm對Al-7Si-0.3Mg合金微觀組織的影響。結(jié)果表明：添加Sm元素之后，合金的二次枝晶間距相比基礎(chǔ)合金的明顯減小；稀土Sm可以顯著細(xì)化片層狀的共晶硅，Sm元素主要形成Al2Si2Sm相。從能量角度，Sm可優(yōu)先與P形成SmP相，可能會抑制AlP相的形成，減弱其促進(jìn)共晶硅形核的效能。隨著Sm元素含量的增加，Al-Si共晶反應(yīng)的過冷度逐漸增大。
關(guān)鍵字: Al-7Si-0.3Mg鋁合金；稀土Sm；微觀組織；細(xì)化機(jī)理
（1. College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China;
2. Electron Microscopy Center, Chongqing University, Chongqing 400044, China;
3. Baotou Research Institute of Rare Earths, Baotou 014030, China）
Abstract:The effect of different contents of rare earth Sm on the microstructure of Al-7Si-0.3Mg alloy was investigated by using multiscale microstructure characterization techniques (i.e., OM, SEM, TEM), XRD and DSC analyses. The results show that the secondary dendrite arm spacing in the Al-7Si-0.3Mg is significantly reduced by Sm addition. Plate-like eutectic Si is refined obviously. Sm is mainly consumed through the formation ofAl2Si2Sm phase. According to the formation energy, the SmP phase easily forms, which could inhibit the formation of AlP phase, and deteriorate the function of AlP phase to eutectic Si in Al alloys. The undercooling of the Al and Si eutectic reaction increases with increasing the Sm content.
Key words: Al-7Si-0.3Mg aluminum alloy; rare earth Sm; microstructure; refining mechanism
