Effect of Rhenium on Microstructure of Directionally Solidified Ni-Based Superalloys with High Chromium Content

Abstract:

The microstructure of high Cr-containing directionally solidified Ni-based superalloys with different Re content were observed by scanning electron microscope. The segregation of alloying elements was also investigated by electron microprobe. According to the observation, the microstructure of as-cast samples included γ, γ', MC carbides and few (γ + γ') eutectic while that of heat-treated samples consists of γ, γ', MC carbides, M₂₃C₆ carbides and Re-containing carbides. With the addition of Re, some conclusions can be made as follows: Re exhibits the strongest degree of segregation to dendrite region and the segregation of Ti, Ta, Al become more serious. The γ' phase of as-cast samples is butterfly-like. For heat-treated samples, the γ' phase evolves from sphere to cube, the size of the γ' phase in the dendrite region decreases from 464 nm to 235 nm while the volume fraction of them barely changes.

• Periodical: Materials Science Forum (Volume 816)
• Pages: 601-607
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.816.601
• Online since: April 2015
• Authors: Xiu Hui Li, Enze Liu, Zhi Zheng
• Keywords: Microstructure, Rhenium, Superalloy

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