Competitive growth of Si and YSi2 phases in a eutectic Si-Y alloy prepared by the Bridgeman method
Competitive growth of Si and YSi2 phases in a eutectic Si-Y alloy prepared by the Bridgeman method
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DOI：
10.1016/j.ceramint.2018.04.150
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发表时间：
2018-08
影响因子：
5.2
通讯作者：
Jinguang Li;R. Hu;Jieren Yang;Yongsheng Liu
中科院分区：
文献类型：
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作者：
Jinguang Li;R. Hu;Jieren Yang;Yongsheng Liu
采用Bridgman法在不同的抽拉速率下制备了定向凝固Si-YSi 2合金。研究了纵截面和横截面的显微组织。随着抽拉速率从0.5 mm/min增加到2 mm/min，YSi 2相的形貌由细小的长条状变为岛状，最后变为沿粗的初晶Si相沿着分布的块状。通过计算各相的界面生长温度，发现Si相和YSi 2相的界面生长温度均随抽拉速率的增加而降低，而共晶组织的界面生长温度基本不变。除此之外，Si相的界面生长温度始终高于YSi 2相。确定了两个临界抽拉速率VC_（1）= 0.96 mm/min和VC_（2）= 1.57 mm/min，当抽拉速率低于VC_（1）时，初生Si相消失，以耦合生长为主。当抽拉速率大于VC 1时，初生Si相开始形成，当抽拉速率大于VC 2时，初生Si相明显增厚。
A directionally solidified Si-YSi2alloy was prepared by the Bridgman method at different withdrawal rates. The microstructures of longitudinal section and cross section were investigated. We observed that as the withdrawal rate increased from 0.5 mm/min to 2 mm/min, the morphology of YSi2phase changed from fine, long strips to islands and finally to blocks distributed along the thick primary Si phase. By calculating the interface growth temperatures of each phase, we found the interface growth temperatures of Si phase and YSi2phase both decreased with withdrawal rate increasing while that of eutectic structure was almost unchanged. Beyond that the interface growth temperature of Si phase was always higher than that of YSi2phase. We determined two critical withdrawal rates ofVC1= 0.96 mm/min andVC2= 1.57 mm/min. Coupled growth was predominant when the withdrawal rate was slower thanVC1and primary Si phase disappeared. Primary Si phase began to form as the withdrawal rate was greater thanVC1and could be obviously thicker as the withdrawal rate was greater thanVC2.