Electrochemical Dy-Alloying Behaviors of Inconel and Hastelloy in Molten LiF–CaF₂–DyF₃

Abstract

The electrochemical Dy-alloying behaviors of Inconel 600 and Hastelloy C-276 were investigated in a molten LiFCaF 2 DyF 3 (0.30 mol%) system at 1123 K. Cyclic voltammetry and open-circuit potentiometry suggested the formation of several phases of DyNi alloys. Potentiostatic electrolysis was conducted to prepare alloy samples using Inconel 600 and Hastelloy C-276 plate electrodes at 0.20 V vs. Li + /Li for 60 min. Cross-sectional scanning electron microscopy revealed that DyNi alloys were formed in both samples. X-ray diffraction analysis confirmed the formation of DyNi 2 as the predominant phase for both the samples. Phase separation of the alloy layer into the DyNi 2 phase and formation of the agglomerated CrFe and CrFeMo phases were indicated by EDX mapping analysis. [

Electrochemical Dy-Alloying Behaviors of Ni-Based Alloys in Molten LiF–CaF₂–DyF₃: Effects of Constituent Elements

“…To develop a more durable alloy diaphragm, we selected Nibased alloys such as Inconel 600 and Hastelloy C-276 as candidates for base materials. 19) We confirmed the presence of aggregated phases of Cr and Mo in DyNi alloy layer in molten LiFCaF 2 DyF 3 salts at 1123 K, wherein, the aggregation degree of Mo was lower than that of Cr. The presence of the aggregated phases in the alloy layer suggested an improvement in the mechanical strength due to precipitation strengthening, however, the actual mechanical strength was not measured.…”

“…For NiCrMo alloy, as reported in Ref. 19), cathodic currents (A) are observed from 0.7 V (vs. Li + /Li) in the negative scan direction, which corresponds to the formation of DyNi alloys. 19) From 0.4 V, cathodic currents (B) and (C) flow consecutively in the negative scan direction, this is due to the formation of DyNi alloys with higher Dy concentrations.…”

“…The details of the experimental setup and procedure have been reported in our previous study. 14,19) LiF (Fuji Film Wako Pure Chemical Corp., >98%) and CaF 2 (Kojundo Chemical Laboratory Co., Ltd., 99.9%) were mixed to an eutectic composition (LiF:CaF 2 = 80.5:19.5 mol%), and 300 g of the eutectic mixture was loaded into a graphite crucible (Toyo Tanso Co., Ltd., IG-110, i.d. 90 mm © height 120 mm).…”

“…Figure 1 shows the cyclic voltammograms for (a) Ni CrMo, 19) (b) NiCr, and (c) NiMo flag electrodes in a molten LiFCaF 2 DyF 3 (0.30 mol%) system at 1123 K. The voltammogram for Ni flag electrode is also given for reference. For NiCrMo alloy, as reported in Ref.…”

Recent Studies on Titanium Refining: 2017–2020

“…The comproportionation reaction between the metal and metallic A d v a n c e V i e w ions has been severely controlled, particularly in rare-metal deposition in fluoride salts. 126,127) The electrochemical Dy-alloying behaviors of Inconel and Hastelloy in molten LiFCaF 2 DyF 3 were studied by Watanabe et al 128) The diffusion of Ti 3+ was investigated in LiFLiCl0.50 mol% Li 2 TiF 6 0.33 mol% Ti at 923 K. The potentials for Ti(III)/Ti(0) and Ti(VI)/Ti(III) in LiFLiCl were reported to be more positive than those in KFKCl. 129) Electrodeposition on the Ni substrate was conducted using K 3 TiF 6 from K 2 TiF 6 and Ti in the water-soluble KFKCl molten salt at 923 K. The deposited film was adherent, compact, and smooth without cracks or voids.…”