Abstract Austenitic alloys such as austenitic stainless steels and Ni-based alloys have been specified as container materials for molten salt reactors (MSRs). In MSR environments, these alloys are susceptible to carburization because (1) graphite components provide a source of carbon, (2) oxide films are not protective in molten halide salts, and (3) MSR operating temperatures fall within the temperature range of carbide formation. Carburization may occur simultaneously with corrosion by the selective dissolution of Cr. To study the corrosion behavior of a carburized microstructure, Hastelloy N, Haynes 244, Haynes 230, and Incoloy 800H samples were pre-carburized at 900°C in a hydrocarbon atmosphere prior to exposure to molten FLiNaK at 700°C. Pre-carburized samples featured a carbide-rich microstructure, particularly near the sample surface. The face-centered-cubic matrix of pre-carburized samples was found to be depleted in Cr, Mo, and to a lesser extent W, which are strong carbide-forming elements. Chromium dissolution in pre-carburized samples was suppressed compared to untreated samples due to the reduction in Cr activity. However, selective attack of the connected carbide structure along grain boundaries was observed in pre-carburized Haynes 230 and Incoloy 800H, which are alloys with high Cr content.

中文翻译：

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预渗碳 Hastelloy N、Haynes 244、Haynes 230 和 Incoloy 800H 在 FLiNaK 中的腐蚀行为

摘要 奥氏体不锈钢和镍基合金等奥氏体合金已被指定为熔盐反应堆 (MSR) 的容器材料。在 MSR 环境中，这些合金易于渗碳，因为 (1) 石墨成分提供碳源，(2) 氧化膜在熔融卤化物盐中没有保护作用，以及 (3) MSR 工作温度落在碳化物形成的温度范围内. 由于 Cr 的选择性溶解，渗碳可能与腐蚀同时发生。为了研究渗碳微观结构的腐蚀行为，Hastelloy N、Haynes 244、Haynes 230 和 Incoloy 800H 样品在暴露于 700°C 的熔融 FLiNaK 之前，在烃气氛中在 900°C 下预渗碳。预渗碳样品具有富含碳化物的微观结构，尤其是在样品表面附近。发现预渗碳样品的面心立方基体中缺乏 Cr、Mo 和少量 W，它们是强碳化物形成元素。由于 Cr 活性降低，与未处理样品相比，预渗碳样品中的铬溶解受到抑制。然而，在预渗碳的 Haynes 230 和 Incoloy 800H 中观察到沿晶界相连的碳化物结构的选择性侵蚀，这些合金是高铬含量的合金。