(1. 中南大学 粉末冶金国家重点实验室，长沙 410083；
2. 中南大学 粉末冶金研究院，长沙 410083)
摘 要: 采用螺旋选晶法制备一种新型无铼镍基单晶高温合金，研究金相腐蚀剂对合金显微组织的影响，以及合金元素的偏析和合金的显微组织。运用金相显微镜(OM)、扫描电镜(SEM)、能谱仪(EDS)、电子探针(EPMA)、X射线衍射(XRD)、电化学萃取、电化学工作站以及图像处理软件Image pro plus(IPP)等技术方法，对镍基单晶高温合金进行表征和研究。结果表明:镍基单晶高温合金铸态组织由γ基体相、γ''''强化相以及γ/γ''''共晶相组成；不同的金相腐蚀剂会形成不同的显微形貌，这是由γ基体相和γ''''强化相在相应腐蚀溶液中的自腐蚀电位决定的，对于γ''''相体积分数的评估，应当选用腐蚀掉γ''''相的图片用于计算；铸态镍基单晶高温合金偏析严重，Cr、Co、W元素偏析于枝晶干，Al、Ta元素偏析于枝晶间。
关键字: 镍基单晶高温合金；金相腐蚀剂；显微组织；γ′相；元素偏析
（1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. Powder Metallurgy Research Institute, Central South University, Changsha 410083, China）
Abstract:A new single crystal nickel-base superalloy was prepared with screw selecting method. The influences of etchants on microstructure, the segregation of alloy elements and the microstructure of alloy were studied. Optical microscope (OM), scanning electron microscope (SEM), energy disperse spectroscope (EDS), electron probe micro analysis (EPMA), X-ray diffraction (XRD), electrochemical extraction, electrochemical workstation and image analysis software image pro plus (IPP) were employed to characterize and study the single crystal nickel-base superalloy. The results show that the casting single crystal nickel-base superalloy is consisted of γ matrix, γ'''' precipitates and γ/γ'''' eutectic. Different etchants can cause different etching results which are determined by self-corrosion potential. As for γ'''' volume fraction evaluation, the γ'''' etchants can provide appropriate results. The segregation of casted single crystal superalloy is severe. The chromium, cobalt and tungsten are dendritic segregation, while the aluminum and tantalum are interdendritic segregation.
Key words: Ni-base single crystal superalloy; metallographic etchant; microstructure; γ′ phase; elements segragaion
