Influence of Metallographic Etchant on γ’ Precipitates Characterization in a Single Crystal Nickel-Base Superalloy

Abstract:

Two metallographic etchants were employed to characterize the γ′ precipitates in a single crystal Nickel-base superalloy. One can corrode γ matrix and retain γ′ precipitates, while the other one can remove γ′ and obtain γ. Potentiodynamic polarization curves of γ′ precipitates and γ matrix in these two etchants were measured to examine the electrochemical process of metallographic etching. The results from the electrochemical tests showed that the corrosion potential (E_corr) of each phase determined the metallographic etching morphology. For γ′ volume fraction evaluation, the quantitative analysis by image analysis software was carried out with the electrolytically extracted γ′ precipitates for the same specimen. Statistics showed that the etchant which selectively etched γ′ precipitates can provide appropriate results.

• Periodical: Materials Science Forum (Volume 849)
• Pages: 563-569
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.849.563
• Online since: March 2016
• Authors: Xiao Li Zhuang, Hong Yu Wu, Jia Yong Si, Liang Jiang
• Keywords: Metallographic Etching, Potentiodynamic Polarization Curve, Scanning Electron Microscopy, Superalloys, γ′ Volume Fraction

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