The degradation of Ni-based superalloys in molten salts is closely related with the evolution of corrosion scales. In this work, the evolution of corrosion scales, the characteristics of the scale/alloy matrix interface associated with the corrosion mechanisms and the corrosion kinetics of a Ni-based superalloy Ni–20Cr–18W in molten salts were investigated. The outer surface of the corrosion scales was composed of numerous flakes. From the cross-sectional view, the scales gradually presented a layered structure and its formation can be ascribed to the morphology evolution of the inclusions inserted within the scales. It was found that the corrosion progress was a cooperative process involving in both oxidation and sulfuration, and the element of sulfur (S) took the precedence to penetrate into the matrix and resulted in an obvious sulfuration zone nearby the scales/alloy matrix interface. The corrosion activation energy of the investigated alloy was calculated to be 125.27 ​kJ/mol. This work is expected to work out the structural evolution of the corrosion scales and the characteristics of the scale/matrix interface associated with the corrosion mechanisms for Ni-based superalloys.

Ni基高温合金在熔盐中的降解与腐蚀规模的演变密切相关。在这项工作中，研究了腐蚀鳞片的演变、与腐蚀机制相关的氧化皮/合金基体界面的特征以及镍基高温合金 Ni-20Cr-18W 在熔盐中的腐蚀动力学。腐蚀鳞片的外表面由许多薄片组成。从横截面看，鳞片逐渐呈现层状结构，其形成可归因于嵌入鳞片内的包裹体的形态演化。发现腐蚀过程是一个涉及氧化和硫化的协同过程，硫元素（S）优先渗入基体，在氧化皮/合金基体界面附近形成明显的硫化区。所研究合金的腐蚀活化能计算为 125.27 kJ/mol。这项工作有望解决与镍基高温合金腐蚀机制相关的腐蚀尺度的结构演变和尺度/基体界面的特征。