Dissolution Of Alloys Research Articles

Mo content-depended competition between Cr2O3 enrichment and selective dissolution of CoCrFeNiMox high entropy alloys

The corrosion and passivation behavior of the as-cast CoCrFeNiMox (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) high entropy alloys (HEAs) are investigated. With the addition of Mo, increasing Mo and Cr riched σ phase precipitates from the primary FCC phase. The corrosion resistance of the CoCrFeNiMox HEAs strongly depends on the phase structure and the passive film. Generally, Mo promotes the selective dissolution of the FCC phase and the enrichment of Cr2O3 in the passive film, the former deteriorates the corrosion resistance while the latter enhances it. Interestingly, the hypoeutectic Mo0.6 exhibits a higher corrosion resistance than that of Mo0.4, eutectic Mo0.8, and hypereutectic Mo1. Analysis of surface passive film and the composition of alloy phases implies that the Cr2O3 enrichment dominates in Mo0.6 while selective dissolution governs in Mox (x = 0.4, 0.8, and 1.0). Mo content-depended competition between the Cr2O3 enrichment and selective dissolution is discussed.

Synthesis of Complex Concentrated Nanoparticles by Ultrasonic Spray Pyrolysis and Lyophilisation

The development of new multicomponent nanoparticles is gaining increasing importance due to their specific functional properties, i.e., synthesised new complex concentrated nanoparticles (CCNPs) in the form of powder using ultrasonic spray pyrolysis (USP) and lyophilisation from the initial cast Ag20Pd20Pt20Cu20Ni20 alloy, which was in the function of the material after its catalytic abilities had been exhausted. Hydrometallurgical treatment was used to dissolve the cast alloy, from which the USP precursor was prepared. As a consequence of the incomplete dissolution of the cast alloy and the formation of Pt and Ni complexes, it was found that the complete recycling of the alloy is not possible. A microstructural examination of the synthesised CCNPs showed that round and mostly spherical (not 100%) nanoparticles were formed, with an average diameter of 200 nm. Research has shown that CCNPs belong to the group with medium entropy characteristics. A mechanism for the formation of CCNPs is proposed, based on the thermochemical analysis of element reduction with the help of H2 and based on the mixing enthalpy of binary systems.

Influence of Heat Treatment on Microstructure and Mechanical Properties of AZ61 Magnesium Alloy Prepared by Selective Laser Melting (SLM).

From previous studies, it is known that the dissolution of β-Mg17Al12 at high temperature and the increase of densities at high pressure after hot isostatic pressing (HIP) are the two main reasons for significant improvement in the ductility of AZ61 magnesium alloy prepared by SLM. However, the mechanism of dissolution of β-Mg17Al12 in SLMed AZ61 magnesium alloy at high temperature is not clear. To illustrate the mechanism of the effect of β-Mg17Al12 dissolution on the ductility of SLMed AZ61 Mg alloy, the effect of solid solution heat treatment (T4) on the microstructure and mechanical properties of SLMed AZ61 was investigated and the kinetic model of β-Mg17Al12 dissolution of SLMed AZ61 magnesium alloy was established. According to the results, there is no significant change in the dissolution of the β-Mg17Al12 with an increase of temperature and time when the T4 temperature is lower than 410 °C. At the optimum solution heat treatment temperature of 410 °C, the dissolution rate is accelerated and the β-Mg17Al12 is completely dissolved after 2 h. In addition, the dissolution rate of β-Mg17Al12 decreases with the increase of dissolution time. The strength of SLMed AZ61 magnesium alloy decreases and the ductility increases as the T4 temperature increases. The strength of the specimens is reduced by grain coarsening (29.2 ± 3.7 μm), but the elongation is increased by 90% compared to SLMed AZ61, due to the effect of β-Mg17Al12 dissolution.

Aluminum Alloy Etching: New Insights By Element Resolved Electrochemical Analysis

Aluminum alloys are pickled and/or etched as a preliminary step prior to anodization or conversion coating. The chemistry of the etching/pickling process must be carefully engineered to avoid the enrichment of the alloying elements such metallic Cu which can interfere with subsequent treatments. Understanding and optimizing the etching process is therefore a major concern for the use of aluminum alloys, and especially, the Cu-rich high strength aluminum alloys.The etching reaction is a mixed potential process similar to other forms of aqueous corrosion. However, the dynamic nature of the interface makes it difficult to apply conventional electrochemistry to determine the rates and mechanisms of the different reactions and therefore, to predict how the etching process will vary with electrolyte composition. Among the many complicating factors, we can cite the very high dissolution rate of the alloy coupled with the formation of gas and the release of intermetallic particles. The dissolution of alloying elements such as Cu and Mg – the reactions of interest – occur at rates several orders of magnitude below that of Al dissolution. For example, Cu dissolution makes a negligible contribution to either electron exchange or mass loss. Finally, the rapid reaction rates and the short time scale of the process preclude the appearance of a true steady state, necessary for the interpretation of many electrochemical techniques.Therefore, to gain insight into the mechanism of the acid etching process, we have used an element-resolved electrochemical technique, atomic emission spectroelectrochemistry (AESEC) (Gharbi et al., 2016; Gharbi et al., 2017; Sultan et al., 2022). This permits the direct measurement of the elemental dissolution rates as a function of time, on an element-by-element basis.In this work, we illustrate the element-resolved electrochemical approach to surface treatment focusing on the acid etching of three alloys: a commercial high-strength AA7449 alloy (containing Zn, Cu, and Mg), and binary Al-Cu and Al-Mg alloys to represent the extremes of alloying element nobility. In sulfuric acid, the binary alloys also represent the extremes of selective versus congruent dissolution. The Al-Mg binary alloy undergoes a simultaneous, congruent dissolution mechanism with Mg dissolving simultaneously with Al. By contrast, the Al-Cu binary alloy exhibits a selective dissolution mechanism with Al dissolving to leave behind dealloyed metallic Cu on the surface of the material. This is ultimately followed by the release of Cu-rich particles due to anodic undermining.The electrolytes investigate in this work represent a range of oxidizing strengths from pure sulfuric acid to pure nitric acid and various mixtures of the two. The effect of Fe(III), an important component of many state-of-the-art etching solutions, was also investigated. Experimental elemental Evans diagrams were determined to clarify the electrochemical nature of the dissolution reactions, specifically how the elemental dissolution rates were related to one another and how they were coupled to the cathodic reactions.An example is shown in the Figure (right), based on the 2022 publication of Sultan et al. On the left, we show a cartoon representation of the dissolution process as determined for a high strength AA7449 alloy. On the right, we show the experimental element-resolved Evans diagram for the same alloy in sulfuric acid. It was found that Cu would not dissolve at the open circuit potential in sulfuric acid, but displayed active dissolution with a well-defined Tafel slope of 44 mV/decade at higher potential. The dissolution rate of Cu in the etching solutions was controlled by the redox potential of the electrolyte as determined by the addition of nitric acid and/or Fe(III). Based on our results, the Fe(III) additive in the presence of nitrate appears to serve a catalytic role, enhancing the rate of electron transfer between Cu and nitrate. The dissolution of Al and Mg were independent of potential suggesting simultaneous dissolution across an oxide film. The rates and mechanisms of Cu particle release will also be discussed.BBM Sultan, D Thierry, JM Torrescano-Alvarez, K Ogle, “Selective dissolution during acid pickling of aluminum alloys by element-resolved electrochemistry”, Electrochim. Acta, 404(2022)139737.O Gharbi, N Birbilis, K Ogle, “In-situ monitoring of alloy dissolution and residual film formation during the pretreatment of Al-alloy AA2024-T3”, J. Electrochem. Soc. 163 (2016)C240.O Gharbi, N Birbilis, K Ogle, “Li reactivity during the surface pretreatment of Al-Li alloy AA2050-T3”, Electrochim. Acta 243(2017)207-219. Figure 1

Microstructural pattern formation during liquid metal dealloying: Phase-field simulations and theoretical analyses

In recent years, liquid metal dealloying (LMD) has emerged as a promising material processing method to generate micro and nano-scale bicontinuous or porous structures. Most previous studies focused on the experimental characterization of the dealloying process and on the properties of the dealloyed materials, leaving the theoretical study incomplete to fully understand the fundamental mechanisms of LMD. In this paper, we use theoretical models and phase-field simulations to clarify the kinetics and pattern formation during LMD. Our study starts from a theoretical analysis of the 1D dissolution of a binary precursor alloy, which reveals that the 1D dissolution process involves two regimes. In the first regime, due to the low solubility of one of the elements in the melt, it accumulates at the solid-liquid interface, which reduces the dissolution kinetics. In the second regime, the interface kinetics reaches a stationary regime where both elements of the precursor alloy dissolve into the melt. Previous works revealed that in the early dealloying stage, the dealloying front is destabilized by an interfacial spinodal decomposition, which triggers the formation of interconnected ligaments. We extend this line of work by proposing a linear stability analysis able to predict the initial length-scale of the ligaments formed in the initial stage of the dealloying. Combining this analysis with the 1D dissolution model proposed here enables us to better understand the initial conditions (composition of the precursor alloy and the melt) leading to a planar dissolution without interface destabilization. Finally, we report a strong influence of solid-state diffusion on dealloying that was overlooked in previous studies. Although the solid-state diffusivity is four to five orders of magnitude smaller than in the liquid phase, it is found to affect both dissolution kinetics and ligament morphologies.

Effect of the Passive Oxide Films Structure and Surface Temperature on the Rate of Anodic Dissolution of Chromium-Nickel and Titanium Alloys in Electrolytes for Their Electrochemical Machining. Part 2. Anodic Dissolution of Titanium Alloys in Nitrate and Chloride Solutions

An experimental study of the anodic dissolution of titanium and its alloys, including pulsed dissolution (up to 100 A/cm2) under control of hydrodynamic conditions and surface temperature in nitrate and chloride solutions, showed that the process is carried out through the electrochemical formation of anodic oxide films (AOF) which can be chemically dissolved. An AOF has a bilayered structure, i.e. two barrier films on the interface with a metal and a solution. Its model is PDM-III (Point Defect Model). At certain conditions, it is possible to achieve a steady state in which the film growth rate is compensated by the rate of its chemical dissolution (observed at pulsed conditions). In this case, over 100% current efficiency based on the ionization of titanium in the oxidation state is achieved. During the conducted experiments, when treated with the direct current, the rate of the electrochemical formation of an AOF exceeded the rate of its chemical dissolution, which led to a decrease in to current efficiency which did not exceed 75%. An increase of the dissolution rate takes place with an increase in the electrolyte flow rate. Upon reaching the thermokinetic instability (TKI) of the AOF (thermal explosion due to a feedback rate of the electrochemical reaction-surface tem-perature-rate of an electrochemical reaction), the interaction of electrolyte components with the surface free of the film takes place, and, as a result, an “anomalous” anodic dissolution is observed with the current efficiency greater than 100%. Regardless the nature of the electrolyte, TKI is achieved at a current density of 1 A/cm2. It is shown that in nitrate solutions with certain parameters of pulsed processing (duty factor 2, dc 50%), the dissolution rate, and, in the case of electrochemical machining, the feed rate of a cathode-tool, can be more than twice higher than the rate of machining with the direct current of the same density.

EFFICIENCY OF WATER-BASED ELECTROLYSIS DEPENDING ON TECHNOLOGICAL PARAMETERS OF CORROSIVE AND ANODE DISSOLUTION OF ALUMINUM

The paper presents the features of the synthesis of hydrogen released as a result of dissolution of the aluminum alloy AMg. To more fully determine the technological characteristics of hydrogen synthesis, we studied the volumes of hydrogen released in the reactor as a result of dissolution of the aluminum alloy AMg. The mechanism of alloy dissolution is established taking into account the effect of impurities in the alloy on the anodic dissolution process. The conditions for accelerating the anodic dissolution of the AMg alloy in the presence of chlorine ions under the conditions of the “negative differential effect” are determined. The dissolution of the AMg alloy in an alkaline chloride solution has an electrochemical nature, which is based on the electrochemical mechanism of hydrogen reduction with the subsequent process of its diffusion into the gas phase. Chloride ions accelerate the active dissolution of aluminum at current densities of 5 A/dm2 instead of 3 A/dm2 at room temperature and surface roughness of class 3-5 (≈5 μm). The greatest influence on the dissolution rate of the alloy has the concentration of NaOH, the dissolution temperature and the surface cleanliness class. The main technological indicator of the improvement of hydrogen electrosynthesis is the use of anodic depolarization of aluminum, its negative values and, as a consequence, the evolution of hydrogen on both electrodes. The depolarization effect is achieved by dissolving the aluminum alloy instead of the oxygen evolution reaction at the anode. The voltage on the cell is 2 times lower compared to industrial alkaline water electrolysis. This makes it possible to save up to 50% of electricity. The absence of oxygen evolution makes this process safer.

Effect of the Passive Oxide Films Structure and Surface Temperature on the Rate of Anodic Dissolution of Chromium-Nickel and Titanium Alloys in Electrolytes for Their Electrochemical Machining. Part I. Anodic Dissolution of Chromium-Nickel Steel in a Nitrate Solution

Experimental study of the chromium-nickel steel Cr18Ni10 anodic dissolution in a nitrate solution with electrical conductivity 0.15 S/cm in a pulse – galvanostatic mode at pulse durations 20–100 µs and current densities 0.01–100 A/cm2, with a change in the duty cycle 10–100% (direct current) at various hydrodynamic conditions and control the surface temperature, that the results obtained are consistent with the hypothesis that the process proceeds through the formation of oxide films of a semiconductor nature with a different type of conductivity (a film containing point defects, Point Defect Model, PDM). Under sta-tionary conditions of the existence of PDM-II, the rate of its electrochemical formation is compensates by the rate of its chemical limiting value of the weight loss per unit of a passed charge (0.16–0.18 mg/C) (takes place under pulse conditions), which corresponds to a cur-rent efficiency close to 100% based on the highest degree of oxidation of the steel compo-nents. When transition to direct current takes place, thermokinetic instability of the film is observed (its formation and destruction due to thermal explosion). Under these conditions, the current efficiency can not only reach 100% based on the lowest degree of oxi-dation of the steel components (thermal activation) but also exceed this value due to the chemical interaction of the electrolyte with the film-free surface.

Anodic dissolution behavior of Zr‐Dy alloy in LiCl‐KCl molten salt

To research Zr-Dy alloy dissolution behavior at anode, the electrode process of LiCl-KCl-K2ZrF6-DyCl3 on an inert W electrode was firstly explored through a group of electrochemical techniques. The depolarization phenomenon was observed owing to the formation of Zr-Dy solid solution, and the redox potentials of Dy(III)/Dy, Zr(II)/Zr-Dy solid solution, Zr(IV)/Zr(II) and Zr(II)/Zr(0) were determined. Then, Zr and Zr-Dy alloy dissolution behaviors at anode were explored by cyclic voltammetry and linear sweep voltammetry. It was confirmed that the rapid dissolution potentials of Zr and Zr-Dy solid solution were observed at −0.86 V and − 1.90 V, and the passivation phenomena of Zr and Zr-Dy solid solution were also observed. Zr-Dy alloy dissolution at anode was conducted employing constant potential (CP) and current (CC) electrolysis. It was found that both Dy and Zr could be dissolved by CC electrolysis. However, Zr dissolution could be controlled by CP electrolysis. Furthermore, Zr-Dy alloy dissolution process was monitored online at different current densities, the dissolution rate increased with the increase of the applied current density.

Green and Effective Anodizing of AA 2024-T3 in Methionine-Sulfuric Acid Electrolyte

Sulfuric acid anodizing (SAA) is a common corrosion protection method for aluminum alloys. Selected additives, usually organic compounds, can be added to the sulfuric acid (SA) electrolyte to improve the corrosion resistance of the anodized layer. It is a widespread opinion that certain organic compounds minimize the dissolution rate of an alloy in the SA electrolyte, thereby improving the structure, morphology, and consequently, the corrosion resistance of the resulting porous film. This work introduces Methionine-Sulfuric Acid (MSA) anodizing as a green and energy-efficient method for developing corrosion-resistant anodic oxide films on AA 2024-T3. Electrochemical investigations at free-corrosion potential revealed that methionine retards the alloy dissolution rate in SA with an inhibition efficiency of above 90%. During anodizing, MSA electrolytes decreased the current density, leading to a decrease in energy consumption of up to 52% compared to the SA counterpart. The Field Emission—Scanning Electron Microscopy (FE-SEM) showed that MSA films have lower thickness and improved pore morphology than SA film generated at the same experimental conditions. The corrosion analyses via salt spray and immersion tests complemented by electrochemical and surface studies indicate superior corrosion performances for MSA films before and after hydrothermal sealing.

A Porous Tungsten Substrate for Catalytic Reduction of Hydrogen by Dealloying of a Tungsten–Rhenium Alloy in an Aqueous Solution of Hydrochloric Acid

Selective dissolution of a tungsten (85 wt.%)–rhenium (15 wt.%) alloy with rhenium in hydrochloric acid at the temperature of 298 K and anodic polarization modes was carried out to develop a porous catalytic substrate and to recycle rare metals. The parameters of the effective selective anodic dissolution of the tungsten–rhenium alloy, including the differences in applied potentials and electrolyte composition, were found. It was established that samples of the tungsten–rhenium alloy possess the smallest average pore size after being exposed for 6000 s. The obtained porous tungsten samples were characterized by X-ray diffraction and scanning electron spectroscopy. A thermodynamic description of the processes occurring during the anodic selective dissolution of a binary alloy was proposed. In the course of the work, the selectivity coefficient was determined using an X-ray fluorescence wave-dispersion spectrometer XRF-1800. The existence of a bimodal structure on the tungsten surface after dealloying was proved.

The influence of butanol on the brass surface morphology during the electrochemical treatment in phosphoric acid solutions

The polarization and gravimetric investigations of the anodic behavior of brass in phosphate-butanol solutions have been carried out. It has been shown that the addition of butyl alcohol to the phosphate electrolyte conditions causes the origination of the effect of electrochemical polishing. The polarization dependencies of the brass anode in the electrolytes containing butanol are peculiar for the metals prone to the passive state transition. The sections of polarization dependences correspond to the active dissolution domain, active–passive state domain, passive brass state domain and the domain of a joint progress of the process of alloy dissolution and oxygen release. The obtained experimental data show the reasonability of the addition of butanol to the phosphate electrolyte to obtain a high quality brilliant metal surface.

Selective dissolution during acid pickling of aluminum alloys by element-resolved electrochemistry

The surface reactivity and the elemental dissolution of a high-strength aerospace alloy (AA7449-T651) during acid pickling was investigated with element-resolved electrochemistry (AESEC). The results demonstrated a sequential dissolution of Mg, Al, Zn and Cu, following the order of their respective galvanic reactivity in common acid pickling solutions. The enrichment of Cu during pickling with the H2SO4 solution was observed. The effect of oxidizing solution components HNO3 and Fe(III) on Cu dissolution were investigated using an experimental Evans diagram approach.

Spontaneous passivation of the CoCrFeMnNi high entropy alloy in sulfuric acid solution: The effects of alloyed nitrogen and dissolved oxygen

The dissolution and passivation kinetics of CoCrFeMnNi high entropy alloys with and without nitrogen addition in 0.1 M H2SO4 were investigated by element-resolved electrochemistry to follow the passivation quasi in situ. The nitrogen containing alloy exhibited spontaneous passivation driven by dissolved oxygen. The alloy without nitrogen did not passivate spontaneously under the same conditions, and its dissolution was accelerated by increasing the dissolved oxygen. This was attributed to an enhanced efficiency of passivation for the nitrogen containing alloy with a lower critical dissolution rate. Both spontaneous and anodic passivation were accompanied by significant Cr accumulation on the surface.

Pitting behavior of the AA6061 alloy and Al5N in a diluted chloride solution

AbstractThe effect of aeration on the pitting potential (Ep) of the AA6061 alloy and high‐purity aluminum (Al5N) is studied in diluted chloride solutions. The Ep values are determined by a potentiodynamic scan in aerated and de‐aerated solutions of 10−3 M NaCl and 10−3 M NaCl + 0.05 M KH2PO4/K2HPO4 buffer. Applying the hypothesis testing procedure, it is concluded that the presence of oxygen in a 10−3 M NaCl solution decreases the Ep for AA6061 by 100 mV and does not affect the Ep for Al5N. This decrease is related to the alloy dissolution around the iron‐rich particles and is analyzed in terms of the model of localized acidification.

The Zr α-phase/(α-phase + hydride) transformation should obey the Phase Rule

The Einstein flux equation is used to predict the apparent temperature hysteresis in hydride precipitation and dissolution in zirconium alloys first observed in 1964. The new interpretation is consistent with Gibbs’ Phase Rule: there can be only one solvus. X-ray diffraction of the remnant hydride record from fracture surfaces of Zr-2.5Nb after delayed hydride cracking showed no dependence on the approach to the test temperature, which is consistent with the predictions of the Einstein flux equation.

Application of pulse current for dissolution of heat-resistant GS32-VI alloy

Objectives. To identify the regularities of electrochemical processing of the heat-resistant GS32-VI alloy in a sulfuric acid electrolyte with a concentration of 100 g/dm3 under the action of a pulsed current in a pulsed mode.Methods. Using the electrochemical technological complex EHK-1012 (developed by IP Tetran) and a non-compensatory method of measuring potential, polarization and depolarization curves with a change in pulse duration and a pause between them were recorded. The current pulses had an amplitude ranging from 0 to 3.5 A (when recording the polarization and depolarization curves), pulse durations ranging from 200 to 1200 ms, and a pause (delay) between pulses ranging from 50 to 500 ms. There were no reverse current pulses.Results. The parameters of the current program that provide the maximum values of the alloy dissolution rate and current output were determined: with a current pulse amplitude of 2 A, a current pulse duration of 500 ms, and a pause duration between pulses of 250 ms, the maximum dissolution rate of the alloy is 0.048 g/h·cm2, while the current output for nickel is 61.6% with an anode area of 10 cm2. The basic technological scheme for processing the heat-resistant GS32-VI alloy, which includes anodic alloy dissolution in a pulsed mode, is proposed.Conclusions. Electrochemical dissolution of GS32-VI alloy under pulsed current action results in an optimal dissolution rate ratio of the alloy components, ensuring the production of a cathode precipitate with a total nickel and cobalt content of 97.5%.

Continuous Heating Dissolution and Continuous Cooling Precipitation Diagrams of a Nickel-Titanium Shape Memory Alloy

Binary NiTi alloys are the most common shape memory alloys in medical applications, combining good mechanical properties and high biocompatibility. In NiTi alloys, the shape memory effect is caused by the transformation of an austenite phase to a martensite phase and the reverse process. Transformation temperatures are strongly influenced by the exact chemical composition of the NiTi phase and the presence of precipitates in the microstructure induced by thermo-mechanical treatment, especially solution annealing and ageing. Isothermal time–temperature precipitation diagrams can be found in the literature. Cooling is frequently not considered, as water quenching is typically assumed to be sufficient. To the best of our knowledge, continuous heating dissolution (CHD) and continuous cooling precipitation (CCP) diagrams do not exist. Differential scanning calorimetry (DSC) is a common method to analyse the austenite/martensite transformation in shape memory alloys, but it has not yet been used to analyse precipitation processes during continuous temperature changes. We have enabled DSC to analyse dissolution and precipitation processes in situ during heating as well as during cooling from the solution annealing temperature. Results are presented as CHD and CCP diagrams, including information from microstructure analysis and the associated changes in the austenite/martensite transformation temperatures.

A Mg alloy with no hydrogen evolution during dissolution

Hydrogen evolution is normally associated with the corrosion or dissolution of Mg alloys in aqueous solutions. This work studied the corrosion behavior of sputtered pure Mg, Mg82Zn18 (at.%), Mg64Zn36 (at.%), and pure Zn in 3.5% NaCl solution. Mg64Zn36 had (i) an amorphous microstructure with some nano-scale grains, (ii) a corrosion rate substantially lower than that of pure Mg, and (iii) no hydrogen evolution during corrosion or anodic dissolution, because the positive corrosion potential retarded the cathodic hydrogen evolution. This is a new route to prevent hydrogen evolution during Mg corrosion, which has never previously been realized.

Operando SQUID Magnetometry for the Characterization of Electrochemical Systems: Charge Transfer in Battery Materials and Electrochemical Dealloying Processes

The combination of magnetism and electrochemistry has attracted considerable attention for application-relevant issues, like the electrodeposition of magnetic thin films or the electrochemically-induced switching of magnetic properties [1,2]. The fact that magnetism variations occurring during electrochemical charging can also serve as diagnostic tool for the corresponding electrochemical processes has been little exploited until now. In this talk, we will demonstrate the capability of operando SQUID magnetometry measurements to characterize electrochemical systems based on two examples: (i) the identification of the electroactive species in Li-ion and Na-ion battery cathodes, (ii) the distinction between different dissolution stages during electrochemical dealloying of Co-Pd alloy.Enabling such operando magnetic studies we have developed a three-electrode electrochemical cell for operation in a commercial state-of-the-art SQUID magnetometer [3].This new cell design allows a precise correlation between the detected variations of the magnetic moment and the electrochemical processes occurring in the investigated sample. Its capability was proven by performing the first in-situ electrodeposition experiments in a SQUID magnetometer [3,4].Applying this new operando technique to (i) Li-ion and Na-ion battery cathodes we could enable a continuous monitoring of the oxidation states of the transition metal ions and therefore an identification of the redox active ions. Our measurements on LiNi0.33Mn0.33Co0.33O2 revealed that first Ni acts as redox active ion and changes its oxidation state stepwise from Ni2+ to Ni3+ and then from Ni3+ to Ni4+. When more than 2/3 of the Li ions are extracted, a simultaneous oxidation of Co3+ and O2- ions takes place that is associated with irreversible capacity losses [5]. Operando magnetic studies on NaV2(PO4)3 cathodes have shown that the vanadium ion is the only ion undergoing oxidation and reduction upon battery operation. However, in the first charging cycle peculiarities in the magnetic susceptibility indicate the occurrence of parasitic side reactions [6].In the case of (ii) in situ dealloying of a Co75Pd25 in a SQUID magnetometer the observed variations of the magnetic moment allowed a distinction between the primary (dissolution of the initial alloy) and secondary (dissolution of residual atoms from porous structure) dealloying steps. The observed transition from alloy ferromagnetism to superparamagnetic behavior, can be ascribed to the formation of Co-rich clusters in the obtained nanoporous Pd framework [7]. Furthermore, the magnetic coupling between these clusters can be reversibly tuned by electrochemical hydrogen intercalation, leading to an On and Off switching of magnetism at room temperature [8].All in all, these two examples prove that operando SQUID magnetometry measurements can serve as a sensitive fingerprint for the processes taking place in various electrochemical systems.Financial support by the Austrian Science Fund (FWF): P30070-N36 is gratefully acknowledged. This work was performed in the framework of the inter-university cooperation of TU Graz and Uni Graz on natural sciences (NAWI Graz).[1] K. Leistner, Curr. Opin. Electrochem. 25 (2021) 100636[2] C. Navarro-Senent et al., APL Mater. 7 (2019) 030701[3] S. Topolovec et al., Rev. Sci. Instrum. 86 (2015) 063903[4] S. Topolovec et al., J. Magn. Magn. Mater. 397 (2016) 96[5] G. Klinser et al., Appl. Phys. Lett. 109 (2016) 213901[6] G. Klinser et al., Phys. Chem. Chem. Phys. 21 (2019) 20151[7] M. Gößler et al., J. Appl. Phys. 128 (2020) 093904[8] M. Gößler et al., Small 15 (2019) 1904523