Understanding of the Corrosion Mechanism of the Ni-Based Alloys in a Nacl-Kcl-Mgcl2 Molten Salt

Abstract

This paper investigated the corrosion of GH3535, Hastelloy C276 and Haynes 230 alloys in a NaCl-KCl-MgCl2 molten salt under Ar gas at 700oC using immersion experiment and microstructure analyses. Forming the Cr-rich phases is an intermediate step of the de-alloying of Cr in the three alloys. The corrosion is driven by the potential difference between the Cr-rich phases and the matrix. The alloying elements affect the Cr-rich phases, which further affect the corrosion behavior of the alloys. The decreased corrosion rate of three alloys with the time is possible related to the remained inert elements and the Cr-rich phases.

Keywords: Ni-based alloy, Chloride molten salt, Precipitated phase, corrosion mechanism