Evolution of the Zr-Cr Eutectic Structure and its Effect on the Oxidation Mechanism of Cr-Coated Zr Alloy at 1350°C

Abstract

The formation, evolution, and inward migration of the Zr-Cr eutectic structure and its influence on the oxidation behavior of Cr-coated Zr alloy at 1350°C were investigated. The lath-shaped eutectic structure was initially formed at the interface after oxidation for 120 s, followed by slow inward migration. After oxidation beyond 180 s, the coating lost its protection and the eutectic structure transformed from lath-shaped into dendrite-shaped. The inward migration was driven by thickening of the ZrO2 and α-Zr(O) layers, and exhibited parabolic growth. The eutectic reaction aggravated the consumption and uneven thickness of the coating, thereby reducing its overall protective performance.

Keywords: Eutectic reaction, Accident tolerant fuel, Cr coating, Oxidation, Diffusion