Evaluating the dissolution corrosion resistance of Hastelloy exposed to liquid lead-bismuth eutectic at 500°C

The present study investigated the dissolution and oxidation corrosion behaviors of Hastelloy exposed to static liquid lead-bismuth eutectic (LBE) at 500 degrees C with an oxygen concentration of 1 x 10(-6) mass%. Hastelloy exhibited better LBE corrosion resistance than the Monel alloy. Both dissolution and oxidation corrosion were observed in Hastelloy, and the maximum LBE penetration depth and spinel layer thickness in the corroded sample after 4000 h of exposure reached 120 +/- 36 and 21 +/- 12 mu m, respectively. Annealing twin boundaries provided favorable paths of accelerated LBE penetration into the matrix, resulting in selective leaching of Ni. Microstructural characterization revealed that the spinel layer formed between penetrated LBE and base metal slowed down the elemental interdiffusion, thereby retarding the dissolution rate. Volumetric changes induced by LBE penetration promoted the formation of stacking faults and dislocations, which could provide more channels for elemental diffusion, leading to the propagation of dissolution attack.