Effect of grain refinement on the corrosion of Ni-Cr alloys in molten (Li,Na,K)F

• Laser remelting greatly decreases the grain size of the coarse grain Ni-Cr alloys.
• Grain refinement remarkably accelerates the dissolution of Cr.
• The corrosion of fine grain Ni-Cr alloys is obviously larger than the coarse grain one.
• The enhanced dissolution of Cr is ascribed to the increasing of overall effective diffusion coefficient of Cr.

The corrosion of cast coarse grain and laser-remelting fine grain Ni-Cr alloys in molten (Li,Na,K)F at 700 °C under Ar has been investigated by electrochemical and thermogravimetric methods with an attempt to understand the effect of grain refinement on the corrosion of the alloys. The results indicate that grain refinement remarkably accelerates the dissolution of Cr, leading to the formation of a wider Cr-depleted zone. The enhanced corrosion of fine grain Ni-Cr alloys could be ascribed to the laser remelting treatment decreasing greatly the grain size of the alloys, and thus significantly increasing the overall effective diffusion coefficient of Cr.