包晶合金定向凝固过程中的对流效应及带状组织形成机制 Ⅰ.实验结果

来源期刊：金属学报2011年第3期

论文作者：骆良顺 张宇民 苏彦庆 王新 郭景杰 傅恒志

文章页码：275 - 283

关键词：包晶合金； 定向凝固； 对流； 偏析； 带状组织

Key words：peritectic alloy； directional solidification； convection； segregation； banding structure

摘    要：利用电阻加热和感应加热Bridgman定向凝固系统对非小平面包晶系模型合金Fe-Ni合金进行系统的定向凝固实验研究,探索2种常规定向凝固条件下对流对包晶合金定向凝固过程中带状组织和宏观偏析的影响规律.发现在高G/V定向凝固过程中,对流使包晶合金定向凝固过程中轴向和径向形成严重的宏观偏析,从而使组织演化异常复杂且难以达到稳态.轴向宏观偏析体现在有限长试样从定向凝固开始至凝固结束都将发生初生相向包晶相的转变过程,转变过程受合金成分和对流强度影响.径向宏观偏析体现在试样心部贫溶质易形成初生相,边缘富集溶质易形成包晶相,在径向上也存在初生相向包晶相的转变过程.

Abstract: Systematic directional solidification experiments were conducted to investigate the convection effects on the banding structure evolution and macrosegregation in nonfaceted-non-faceted model Fe-Ni alloy using conventional resistance heating and induction heating Bridgman directional solidification methods in this paper.It was found that convection can induce severe axial and radial macrosegregation in the directionally solidified samples,and make the microstructures complex and make the steady state difficult to achieve.Axial macrosegregation was reflected in finite samples solidified from the beginning to the end of solidification with the transition from primary phase to peritectic phase.The primary-peritectic transition depended on the alloy composition and convection strength.Radial macrosegregation reflected in the solute concentration poor in the center and rich in edge,and a primary-peritectic transition also exist in the lateral directional from the sample to the edge.