GH141合金的凝固偏析特性及均匀化处理

Solidification segregation characteristic and homogenization treatment of GH141 superalloy

利用光学显微镜、扫描电镜及能谱分析仪分析了经真空感应+真空自耗冶炼的GH141合金自耗锭的铸态组织及凝固偏析特性,并研究了均匀化处理温度和时间对GH141合金微观组织、析出相、元素偏析情况的影响规律。结果表明,GH141合金铸锭存在明显枝晶偏析,Ti、Mo偏聚于枝晶间,Al、Co、Cr偏聚于枝晶干;枝晶间主要析出相为MC和M_(6)C+M_(23)C_(6)碳化物。在均匀化过程中,随着均匀化温度的升高和时间的延长,枝晶组织消除、碳化物回溶、偏析元素逐渐扩散均匀;经1190℃×48 h均匀化处理后,合金成分基本均匀,大部分碳化物已回溶。

Segregation characteristics and microstructure of the as-cast GH141 superalloy ingot prepared by vacuum induction melting(VIM) and vacuum arc remelting(VAR) were investigated by means of optical microscope(OM), scanning electron microscope and energy dispersive spectroscopy(EDS). Meanwhile, the effect of homogenization temperature and time on evolution of microstructure, precipitates and segregation of the GH141 superalloy was also studied. The results show that the as-cast GH141 alloy exhibits dendritic segregation, in which Ti and Mo are segregated to the interdendritic regions, while Al, Co and Cr are segregated to the dendrites. The main precipitates are MC, M_(6)C and M_(23)C_(6)carbides in interdendritic regions. With the increase of homogenizing temperature and holding time, dendrite structure is eliminated, carbides are redissolved and segregation elements are gradually distributed evenly by diffusion. It is found that the element segregation is basically eliminated and most of the carbides are redissolved in the GH141 alloy after homogenization at 1190 ℃ for 48 h.