(1. 中南大學(xué) 粉末冶金國家重點實驗室，長沙 410083；
2. 中南大學(xué) 粉末冶金研究院，長沙 410083)
摘 要: 采用螺旋選晶法制備一種新型無錸鎳基單晶高溫合金，研究金相腐蝕劑對合金顯微組織的影響，以及合金元素的偏析和合金的顯微組織。運用金相顯微鏡(OM)、掃描電鏡(SEM)、能譜儀(EDS)、電子探針(EPMA)、X射線衍射(XRD)、電化學(xué)萃取、電化學(xué)工作站以及圖像處理軟件Image pro plus(IPP)等技術(shù)方法，對鎳基單晶高溫合金進行表征和研究。結(jié)果表明:鎳基單晶高溫合金鑄態(tài)組織由γ基體相、γ''''強化相以及γ/γ''''共晶相組成；不同的金相腐蝕劑會形成不同的顯微形貌，這是由γ基體相和γ''''強化相在相應(yīng)腐蝕溶液中的自腐蝕電位決定的，對于γ''''相體積分數(shù)的評估，應(yīng)當選用腐蝕掉γ''''相的圖片用于計算；鑄態(tài)鎳基單晶高溫合金偏析嚴重，Cr、Co、W元素偏析于枝晶干，Al、Ta元素偏析于枝晶間。
關(guān)鍵字: 鎳基單晶高溫合金；金相腐蝕劑；顯微組織；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
