深过冷Al-70%Si合金的凝固特性与微观组织

发布时间：2018-12-27 15:22

【摘要】：通过电磁悬浮(EML)熔炼设备对Al-70%Si合金进行深过冷处理,利用高速摄影仪(HSC)和SEM分别对凝固过程和凝固后的组织进行了观测,研究了不同过冷度下初生Si的生长规律.结果表明,过冷度对初生Si的生长有很大影响.当过冷度较小时,初生Si为粗大的长条状,有特殊的边和面,且具有明显的孪晶痕迹,表现出小平面生长的特征;当过冷度较大时,初生Si为细小的枝晶和球状晶,表面光滑,表现出非小平面生长的特征;当过冷度居于中间时,初生Si为粗大的块状和规则排列的枝晶状,块状有特殊的边和面,枝晶表面光滑,表现出小平面和非小平面混合生长的特征.随着过冷度的增加,初生Si的生长方式由小平面生长转变为中间方式生长,再由中间方式生长转变为非小平面生长,生长方式间发生转变的临界过冷度分别为122和230 K.
[Abstract]:The supercooling treatment of Al-70%Si alloy was carried out by means of electromagnetic suspension (EML) melting equipment. The solidification process and microstructure after solidification were observed by high speed photography (HSC) and SEM, respectively. The growth law of primary Si under different undercooling was studied. The results showed that undercooling had a great effect on the growth of primary Si. When the undercooling degree is small, the primary Si is a coarse strip with special edges and surfaces, and has obvious twin trace, which shows the characteristics of small plane growth. When the undercooling degree is high, the primary Si is fine dendrite and globular crystal, and the surface is smooth, showing the characteristics of non-small plane growth. When the undercooling degree is in the middle, the primary Si is coarse block and regular arrangement dendrite. The block has special edge and surface, and the dendritic surface is smooth, showing the characteristics of small plane and non-small plane mixed growth. With the increase of undercooling degree, the growth mode of primary Si changed from small plane growth to intermediate growth mode, and then from intermediate mode to non-small plane growth. The critical undercooling degree of transformation between growth modes was 122and 230K, respectively.
【作者单位】：西安工业大学陕西省光电功能材料与器件重点实验室;
【基金】：国家重点基础研究发展计划项目2011CB610403 国家自然科学基金项目51171136、51301125、51401156和51371133资助~~
【分类号】：TG146.21;TG156.91

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