Al-Si-Mg-Sc铸造合金微观组织演变及其细化变质机制  

Microstructure Evolution and Mechanism of Refinement and Modification in As-casting Al-Si-Mg-Sc Alloy

作　　者：崔晓明[1] 孟闯 石博 白朴存[1] 杜赵新[1] 赵学平 王慧新 Cui Xiaoming;Meng Chuang;Shi Bo;Bai Pucun;Du Zhaoxin;Zhao Xueping;Wang Huixin(Inner Mongolia University of Technology,Hohhot 010051,China)

机构地区：[1]内蒙古工业大学,内蒙古呼和浩特010051

出　　处：《稀有金属材料与工程》2022年第7期2529-2535,共7页Rare Metal Materials and Engineering

基　　金：内蒙古科技计划项目(201802029);内蒙古自治区科技重大专项(zdzx2018031)。

摘　　要：本研究利用真空感应熔炼炉制备了Al-7%Si-0.3%Mg-X%Sc(X=0, 0.1, 0.2, 0.3, 0.5, 0.8)铸造合金。采用扫描电子显微镜(SEM),能谱仪(EDS)和透射电子显微镜(TEM)等测试手段,表征了实验合金的微观组织,探讨了实验合金的细化变质机制。结果表明:实验合金主要物相包括α-Al、共晶Si、Al3Sc、AlSc2Si2、富铁相(β-AlFeSi和π-AlSiMgFe)等。添加Sc元素后的实验合金组织均得到细化。随着Sc含量的增加,α-Al枝晶间距减小,共晶Si尺寸变小。当Sc含量为0.3%时,实验合金细化效果最好。α-Al细化主要归功于含Sc合金中产生大量细小的Al3Sc颗粒与基体α-Al共格,且二者晶格错配度为1.0%,Al3Sc可以作为α-Al的有效异质形核质点。添加Sc后的共晶Si发生变质及得到细化,这是因为存在于共晶Si中的稀土Sc元素,可以作为杂质元素被吸附在共晶Si{111}密排面上,从而促发共晶Si形成孪晶。此外,合金中形成的AlScSi能够消耗部分Si元素,使得共晶Si数量减少、尺寸减小。Al-7%Si-0.3%Mg-X%Sc(X=0, 0.1, 0.2, 0.3, 0.5, 0.8) casting alloys were prepared by vacuum induction melting furnace.Scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and transmission electron microscopy(TEM) were used to characterize the microstructure of the experimental alloy, and the refinement and modification mechanism of the experimental alloy was discussed. The results show that the main phases of the experimental alloy include α-Al, eutectic Si, Al3Sc, AlSc2Si2 and iron-rich phases(β-AlFeSi and π-AlSiMgFe). The microstructure of the experimental alloy is refined by adding Sc element. With the increase of Sc content,the dendritic spacing of α-Al decreases and the size of eutectic Si decreases. When the content of Sc is 0.3%, the effect on refining of the experimental alloy is the best. A large number of fine AlSc particles produce in the alloy containing Sc. AlSc particles are coherent with α-Al matrix, and the lattice mismatch between them is 1.0%. Therefore, AlSc can be used as an effective heteronucleation particle of α-Al to fine α-Al. After the addition of Sc, the eutectic Si will deteriorate and get refined. This is because the rare earth Sc elem ents existing in the eutectic Si can be adsorbed on the eutectic Si{111} dense surface as impurity elements, thus promoting the formation of h igh-density twins for the eutectic Si. In addition, AlScSiformed in the alloy can consume part of Si element, which reduces the amount and size of eutectic Si.

关 键 词：AL-SI-MG合金 稀土Sc 微观组织 细化变质机制 

分 类 号：TG146.21[一般工业技术—材料科学与工程]