UBC Faculty Research and Publications

The Performance of Different Etchants on the Carbides of Ni600 and Ni625 Fang, Ning; Zhou, Ziyao; Britton, Ben

Abstract

Nickel-based alloys that contain chromium are widely used in corrosion-resistant applications in industry, but they are sensitive to the environment when the passive chromium oxide layer is damaged. In Ni600 and Ni625 alloys, precipitates can deplete the surface layer of chromium oxide. To better characterize and analyze the nickel alloy surfaces and their chromium carbides, chemical etching with different etchants and electrolytic etching were applied to sample surfaces. This paper revealed their efficacy in etching various carbides within the nickel alloys, and orange phases ranging from 2 to 20 μm in optical micrographs were identified as titanium-containing compounds. Carbides located on the grain boundaries were determined to be Cr23C6 and were surrounded by chromium-depleted zones. The findings and figures in this paper provide a more intuitive reference for future analysis of carbides and titanium nitrides, enhancing the understanding of their impact on the corrosion resistance of these alloys, which will not only contribute to the material science field but also aid in developing the Ni-based alloys for industrial applications.

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