Corrosion of martensitic and austenitic steels in liquid gallium
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Corrosion of martensitic and austenitic steels in liquid gallium F. Barbiera) and J. Blanc CEA - CEREM / SCECF, BP 6, 92265 Fontenay-aux-Roses cedex, France (Received 16 October 1997; accepted 23 July 1998)
The compatibility of 1.4914 martensitic steel and 316 L austenitic stainless steel has been studied in the presence of static liquid gallium. It was shown that the materials are severely attacked by the liquid metal. The corrosion is characterized by the formation of a reaction layer identified as FeGa3 . Depending on the steel, the growth kinetics and the morphology of the layer are found to be different. In the case of 1.4914 steel, the growth law is linear, which implies an interface controlled regime. Moreover, the layer formed from an initially rectangular substrate exhibits a typical cruciform pattern. In the case of 316 L steel, a parabolic growth is found after a transient period, indicating a process mainly controlled by diffusion. Contrary to the martensitic steel, the morphology of the layer occurring during the solid-liquid interaction leads to complete coverage of the 316 L substrate, with rounded edges.
I. INTRODUCTION
The contact between a solid material and a liquid metal is found in various technological fields such as casting, welding, brazing, hot-dip coating, and heat transfer using liquid metals as coolants.1–5 When solids are exposed to liquid metal environments, dissolution of the solid and formation of reaction products between major or minor elements are commonly occurring phenomena.6 In many cases, these processes can lead to modification of solid and liquid properties (solid thickness loss and liquid penetration along the grain boundaries, mechanical integrity reduction, crystallization of solute in liquid phase, deposition, . . .). Consequently, corrosion considerations are important in selecting the appropriate material or the operating parameters. The purpose of this work is to examine the interaction between steels and molten gallium. In fact, gallium is under consideration for use as a liquid-metal, heattransport medium in the field of nuclear fusion reactors since it remains liquid over a wide temperature range (30 to 2300 ±C), exhibits good thermal conductivity, and has a very low vapor pressure.7 However, gallium has a high affinity for many metals and alloys.8 –10 For example, it is well known that aluminum and zinc disintegrate in liquid gallium at 30 ±C11,12 Consequently, a major concern regarding the use of gallium as a liquid coolant is its compatibility with containment materials. The behavior of gallium with some candidate materials for fusion reactors has thus to be determined.
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Address all correspondence to this author. e-mail: [email protected] J. Mater. Res., Vol. 14, No. 3, Mar 1999
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In this work, the compatibility of 1.4914 martensitic steel and 316 L austenitic stainless steel has been studied in the presence of static gallium under isothermal conditions
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