Evolution of the Zr-Cr eutectic structure and its effect on the oxidation mechanism of Cr-coated Zr alloy at 1350 °C

The formation, evolution, and inward migration of the Zr-Cr eutectic structure and its influence on the oxidation behavior of the 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 migration distance of the Zr-Cr eutectic liquid exhibited parabolic-like distribution and was approximately equivalent to the combined thickness of the ZrO 2 and α-Zr(O) layers. The eutectic reaction aggravated the consumption and uneven thickness of the Cr coating, thereby reducing its overall protective performance.