Background: The demand for energy is growing with the rapid population growth and the expansion of the economy. As one of the six most promising Generation IV reactors

Thorium Molten Salt Reactor (TMSR) has been attracting increasing attention. Unlike the traditional Pressure Water Reactor (PWR)

operating temperature of TMSR is varying from 565 oC to 850 oC and the nuclear fuels are dissolved in the molten salt LiF-BeF2-ZrF4-UF4 (65-29.1-5-0.9 mol%). Considering the causticity of the molten salt

there are more stringent demands on the loops materials

including good mechanical properties

low activity

good chemical compatibility with the molten salt

and resistance to corrosion. To ensure the safe operation of the reactor

it is necessary to investigate the behavior of loop material corrosion in high-temperature molten salt. Purpose: This study is to explore the corrosion mechanism based on the change of microstructure and weight of the alloys corroded with same corrosion time and different corrosion temperatures. Methods: Data for the weight loss of the alloys before and after corrosion were obtained by weighing experiment. To identify microstructure changes of the alloys after corrosion

Scanning Electron Microscope/Energy Dispersive Spectrometer (SEM/EDS) were applied to measure the micro-elements changes and obtain corrosive morphology. Results: After molten salt corrosion

corroded areas of all samples exhibited enrichment of Mo and Cr elements loss. Considering the Cr oxides and fluorides generated during etching in the saturation solubility of the molten salt

which will be deposited on the surface of the alloy to form a protective layer for certain inhibition to corrosion

resulting the corrosion weight loss increases but the increasing rate decreases with the temperature of corrosion rises. Be different from the un-corroded alloy

grain boundary structure of the alloy revealed significantly widened after corrosion

and the grain size occurs after the first refinement coarsening phenomenon as the corrosion temperature increases. Conclusion: Corrosive environment has a great impact on alloy corrosion

molten salt corrosion showed significant intergranular corrosion characteristics

and corrosion at different temperatures showed different corrosion characteristics due to the effect of temperature on the rate of diffusion of atoms. Abstract