Nickel-manganese Alloys Research Articles

Facile synthesis of electrospun transition metallic nanofibrous mats with outstanding activity for ethylene glycol electro-oxidation in alkaline solution

Electrospinning technique was exploited to prepare a series of nickel-manganese alloy on carbon nanofibers [NiMn@CNFs] in various Ni:Mn wt.% ratios by using the corresponding acetate salts at 20 kV, followed by a calcination process for the obtained metallic fibrous mats at 850 °C for 5 h. The crystalline structure, morphology and chemical constituents of formed nanocomposites were determined by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analyses. The electrocatalytic activity of different NiMn@CNFs nanomaterials for oxidizing ethylene glycol molecules was evaluated in NaOH solution through cyclic voltammetry and steady state polarization measurements. The presence of increased content of manganese in NiMn@CNFs nanocomposite significantly affected its electrochemical performance. Adding 40 wt.% Mn in the synthesized nanomaterial was sufficient to achieve the optimum oxidation current density with the best stability when compared to that of Ni@CNFs. The present work opens a new route for fabricating many binary and ternary transition metals-based fibrous mats by using the electrospinning technique and examining their electrochemical activity for renewable energy applications.

Microwave decomposition of nickel(III) oxide–manganese dioxide in vacuum

ABSTRACTIn this article, microwave was used for producing nickel–manganese alloy from nickel (III) oxide–manganese dioxide mixture in vacuum, and the heating processes and reaction mechanisms were also explored. When the nickel (III) oxide–manganese dioxide mixture was 20.0 g, the mixture can be heated and decomposed as the microwave powers were higher than 542 W, and the minimum power value making the system warm up to granulate was lower than that of the single-nickel (III) oxide or the single-manganese dioxide. With 740 W microwave power, the mixture can be heated and decomposed to gather and form the large diameter spherical particles of smelting nickel–manganese alloy. The average sizes of the particle were mainly 0.25 mm and 0.32 mm in diameter, accounted for 40.5% or 26.1% (wt%), respectively. The sizes of the particles enlarged with the increase of microwave powers. The reaction mechanisms have been put forward, and the processes can be divided into five steps: the electric spark reaction, the first reaction, the secondary reaction, and granulation. The critical point of the first reaction and the secondary reaction was 560°C and 1870°C, respectively. It was found that the mid-heating rates were higher than the post-heating rates; moreover, the late stage was the cooling process. Besides, a three-point analysis leading to the phenomenon was proposed. When the microwave power was 800 W, the elemental content limit was 68.7% and 16.3% after the decomposition of 20.0 g nickel (III) oxide–manganese dioxide under vacuum and in air, respectively.

Electrooxidation of methanol on NiMn alloy modified graphite electrode

Nickel and nickel–manganese alloy modified graphite electrodes (G/Ni and G/NiMn) prepared by galvanostatic deposition were examined for their redox process and electrocatalytic activities towards the oxidation of methanol in alkaline solutions. The methods of cyclic voltammetery (CV), chronoamperometry (CA) and impedance spectroscopy (EIS) were employed. In CV studies, in the presence of methanol NiMn alloy modified electrode shows a significantly higher response for methanol oxidation. The peak current of the oxidation of nickel hydroxide increase is followed by a decrease in the corresponding cathodic current in presence of methanol. The anodic peak currents show linear dependency upon the square root of scan rate. This behavior is the characteristic of a diffusion controlled process. Under the CA regime the reaction followed a Cottrellian behavior and the diffusion coefficient of methanol was found to be 4 × 10 −6 cm 2 s −1. A mechanism based on the electro-chemical generation of Ni 3+ active sites and their subsequent consumptions by methanol have been discussed and the corresponding rate law under the control of charge transfer has been developed and kinetic parameters have been derived. The charge transfer resistance accessible both theoretically and through the EIS have been used as criteria for derivation of the rate constant.

Fast Epitaxial High Temperature Brazing of Single Crystalline Nickel Based Superalloys

A new high temperature brazing technology for the repair of turbine components made of single crystalline nickel based superalloys has been developed. It allows the repair of single crystalline parts by producing an epitaxially grown braze gap within very short times. In contrast to commonly used brazing technologies, the process is not diffusion based but works with consolute systems, particularly nickel-manganese alloys. Brazing experiments with 300 μm wide parallel braze gaps, as well as V-shaped gaps with a maximum width of 250 μm, were conducted. Furthermore, thermodynamic simulations, with the help of THERMOCALC software, Version TCR, were carried out to identify compositions with a suitable melting behavior and phase formation. With the new alloys complete, epitaxial bridging of both gap shapes has been achieved within brazing times as short as 10 min.

Hydrogen evolution characteristics of Ni–Mn microencapsulated MlNi 3.03Si 0.85Co 0.60Mn 0.31Al 0.08 alloys in 6 M KOH

Nickel–manganese alloys were coated from sulphate baths by electrodeposition with ‘Packed Bed’ technique on the surface of proprietary lanthanum rich non-stoichiometric MlNi 3.03Si 0.85Co 0.60Mn 0.31Al 0.08 (Ml = lanthanum rich misch metal) hydrogen storage alloy particles. The structure and nature of the microencapsulated alloys were characterized using X-ray diffraction (XRD) and electron paramagnetic resonance (EPR). The hydrogen evolution reaction (HER) was investigated in 6 M KOH at 30 °C by galvnostatic cathodic polarisation technique. The effects of Ni/Mn ratio in the bath and deposition current density were studied. Among the investigated depositions, Ni 150Mn 100 (30) and Ni 150Mn 10 (60) (concentration of Ni and Mn salts in electrodeposition bath given in grams per liter; electrodeposition current density (CD) given within brackets in milliamphere per square centimeter) coated samples exhibited the highest activity towards the HER. It can be concluded that disordered paramagnetic coatings with Ni concentrations above 80 at.% exhibit higher catalytic activity towards HER. The Tafel mechanism is the easiest pathway for HER on most of the studied coatings. However, some of the Ni-rich coatings prefer the Volmer–Tafel path and one sample [Ni 150Mn 150 (80)] prefers the Heyrovsky–Volmer path.

Influence of the Plating Conditions on the Structure and Corrosion Resistance of the Ni-Mn Alloy

This paper reported the electrodeposition of the nickel manganese alloy coatings from a sulphate bath using sodium citrate as complexing agent. The cyclic voltammetric experiments showed that the alloy initiative codeposition potential was about –0.457 V (vs.SCE). The effect of the plating conditions on the composition and the structure of the Ni-Mn were studied by energy dispersive X-ray spectrum and X-ray diffractometer, respectively. As a result, with the increase of the cathodic current density from 10 to 40 mA·cm-2, the manganese content of the deposit increased from 4.4 at% to 10.3 at%, and then it slightly decreased. The phase structure of the coating was face centered lattice (Fm3m) Ni-Mn solid solution. The corrosive polarization experiments indicated that the deposit could work as sacrificial coating for carbon steel in 3.5 wt% sodium chloride solution.

Magnetic properties of electrodeposited nickel-manganese alloys: Effect of Ni/Mn bath ratio

with detergent followed by a final washing in distilled water. The edges of the panels were masked with lacquer. An area of 4 cm · 5 cm on both sides was left exposed to the electrolyte during plating. Efforts were initially made to study the preparation of practical deposits obtained from solution of pH 3. No attempt was made to take into consideration pH changes during deposition. The deposited alloys were mechanically removed from the substrate and studied. The microstructures were examined using a Leica Reichert Polyvar metallurgical optical microscope under bright field. The magnetic hysteresis experiments on the deposits were performed using a PAR EGsG vibrating sample magnetometer. The X-ray diffraction of the deposits was carried out using a Guinier type camera employing a focusing geometry and a solid-state detector. The radiation used was CuKa1. The chemical composition of the alloy was determined using standard analytical procedures wherein nickel was estimated by gravimetric analysis as Ni‐DMG complex and manganese by spectrophotometric analysis.

The removal of nickel dissolved in Pb—17Li by the formation of a less soluble nickel—manganese alloy

Structural steels are susceptible to dissolution when exposed to liquid Pb—17Li. In order to remove the corrosion products transferred into the alloy, purification systems may be used. The efficiency of a cold trap fitted to the Anapurna liquid metal loop has been studied. The removal of nickel from solution in Pb—17Li has been shown to be possible by adding manganese to the Pb—17Li. Experiments carried out with a cold trap temperature of 523 K and an alloy temperature of 673 K have shown that nickel concentration as low as 1 wppm may be achieved by this method. The result is interpreted by the formation of nickel—manganese compounds deposited in the cold parts of the trap. This observation which suggests an interaction between both nickel and manganese in Pb—17Li is confirmed by equilibrium tests of Ni Mn alloys with Pb—17Li.

CARPENTER NICKEL 211 ALLOY

Abstract CARPENTER NICKEL 211 ALLOY is a nickel-manganese alloy that is slightly harder than commercially pure nickel (Nickel 200). It is a solid-solution strengthened alloy. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: Ni-361. Producer or source: Carpenter.

The variation of sublattice moment with composition for antiferromagnetic nickel-manganese alloys

Neutron diffraction from polycrystalline samples containing from 30 to 90 at% Mn has been used to follow the variation of the sublattice moment with composition. The 30 at% sample is not antiferromagnetic at 7 K but the 35 at% sample is antiferromagnetic with a moment of 0.65μ B. As the Mn concentration is increased the sublattice moment increases monotonically, and finally linearly, extrapolating through the composition gap at about 50 at% Mn where the face centred cubic phase is not stable.

Thermodynamics of nickel-manganese alloys using oxide and fluoride electrolytes

Activities of manganese in nickel-manganese alloys have been determined over the temperature range 950 K to 1348 K by a galvanic cell technique, using fluoride and oxide electrolytes. The activities of manganese show negative deviations from Raoult’s law over the entire range of composition studied. Various phase transformations involved in the system have been analyzed using the thermodynamic data obtainable from the present investigation.

Oxidation of nickel-manganese alloys in the temperature range 873?1273 K

Ni-Mn alloys containing up to 38% Mn have been oxidized in pure oxygen between 873 and 1273 K and the parabolic rate constants measured. The scale morphologies and oxide compositions are interpreted in terms of modifications to the scale on pure Mn caused by the presence of Ni. The scales are composed predominantly of two layers at all temperatures, giving the sequences of phases alloy/cubic monoxide (Ni, Mn)O/ternary spinel, with the cubic (Ni, Mn)O layer always having the greater thickness. There is limited evidence for a third, very thin, outer layer in the scales on all alloys at 873 K and for Ni-38%Mn at 1073 K, which is tentatively considered to be Mn2O3, giving layers in the order alloy/cubic monoxide/ternary spinel/Mn2O3, by analogy with the scale formed on pure Mn. The distribution of the alloy components in the scale is discussed in relation to the Ni-Mn-O phase diagram and in terms of recent theoretical treatments of solid solution scale formation on binary alloys, as far as the available diffusion data allow. The occurrence of internal and intergranular oxidation and the formation of a Mn-depleted zone coincident with the band of uniform internal oxide are considered briefly.

Superparamagnetism and spin-glass freezing in nickel-manganese alloys

An experimental study of the ac susceptibility, magnetization, and thermoremanent magnetization has been made for atomically disordered and weakly ordered ${\mathrm{Ni}}_{3}$Mn. Superparamagnetism with cluster interaction is demonstrated by Curie-Weiss behavior above the susceptibility peak temperature and a Langevin dependence of the magnetization. Blocking is suggested by a weak frequency dependence of the susceptibility peak and an increase in hysteresis below the peak temperature. Spin freezing, which fixes the direction of the local anisotropy, is examined by thermoremanent magnetization measurements.

Exchange-anisotropy field in disordered nickel-manganese alloys

Magnetization data for disordered and weakly ordered Ni-Mn alloys from 22.1 to 32.1 at.% Mn have been obtained upon warming from 4.2 to 300 K, for measuring fields up to 100 kOe, after first cooling from 300 to 4.2 K in zero field or in 100 kOe. The measurements show that there is a minimum measuring field for which the data for zero-field cooling match the data for field cooling. This field, for the disordered alloy, increases from 10 kOe at 22.1 at.% Mn to 90 kOe at 32.1 at.% Mn. Partial atomic ordering reduces this coupling field. The coupling field is smaller than expected from previous studies. The data are qualitatively explained by a recently proposed local-environment model which considers explicitly the nearest-neighbor environment of Mn atoms in the alloy.

High field magnetization in equilibrium ordered nickel-manganese alloys

The equilibrium ordered states for 400°C and 500°C annealing in Ni-Mn alloys near the Ni <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Mn composition have been investigated. The results indicate distinctly different order configurations for the two temperatures. At 400°C, homogeneous long range order results, with a saturation magnetization which is relatively insensitive to composition. At 500°C, the data suggest that the ordering is inhomogeneous, with the nucleation and growth of stoichiometric Ni <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Mn clusters in a Mn-or Ni-rich matrix, depending on composition.

TECHALLOY NICKEL 211

Abstract TECHALLOY Nickel 211 is a nickel-manganese alloy with good elevated-temperature resistance to corrosion by sulfur compounds. When annealed, it is slightly stronger and harder than Techalloy Nickel 200 and is good for structural parts subjected to degassing temperatures. Nickel 211 has low electron emission and is used for such applications as electron tubes and sparkplug electrodes. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-248. Producer or source: Techalloy Company Inc..

NIMAG 111

Abstract NIMAG 111 is a nickel-manganese alloy possessing good resistance to corrosion by sulfur compounds at elevated temperatures. It is recommended for such applications as electron tubes. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-231. Producer or source: Spang Industries Inc..

Thermodynamic character of the order-disorder transition in nickel-manganese alloys

X-ray investigation of a nickel-manganese alloy (26.8-at.% Mn) shows the existence of an extensive two-phase field between the disordered and ordered forms. Recent observations of "critical slowing down" in this system must therefore be interpreted with caution.

Anodic Polarization Behavior of Nickel-Manganese Alloys in 1N Sulfuric Acid Solution

Abstract The anodic polarization behavior of six alloys in the nickel-manganese system in hydrogen saturated 1N sulfuric acid was investigated at 20 C (68 F) using a potentiodynamic technique. Only the nickel free alloy failed to exhibit passivity. The potential width of the passive region for those specimens exhibiting passivity decreased, and the passive current density increased with increasing manganese content. The corrosion potential decreased with increasing manganese content. The critical current density was nearly constant for all passive specimens except pure nickel. Nickel-manganese alloys exhibited marked secondary passivation at potenitals just slightly more active than those at which visible oxygen evolution occurred. It was also noted that among elements 22 through 29, passivity occurs in the above environment only in the even numbered elements.

Hyperfine Fields at Fe57 in Nickel–Manganese Alloys

AbstractCo57‐doped alloys of nickel with manganese in the concentration range 0 to 33 at%, have been studied using Mössbauer spectroscopy at 77°K and some higher temperatures. The alloys were suitably heat treated for maximum ordering. The alloys with small Mn concentration showed simple magnetic h.f.s. while the higher concentration alloys exhibited complex behaviour. This is attributed to the co‐existence of long‐range ordered and disordered phases and accordingly these spectra could be resolved into contributions originating from two Fe57 sites by least squares fitting. A further check was obtained by disordering an alloy near Ni3Mn by quenching from 800°C, whereupon a simple h.f. pattern resulted. The Fe57 hyperfine fields in these alloys as a function of Mn concentration showed no variation except in the case of the long‐range ordered phase near Ni3Mn where the field was higher by about 20%. incidentally, the saturation magnetic moment of the alloy also showed a maximum in this region. It is shown that the Co57 atoms are likely to occupy the nickel sites in the case of the ordered stoichiometric alloy Ni3Mn.