Surface Of Amorphous Ribbons Research Articles

Corrosion of Pure Magnesium and Binary Magnesium Alloy in Ringer's Solution

The work presents monitoring of the corrosion rate for pure magnesium and the binary magnesium alloy Mg72Zn28. Alloying elements with a purity of 99.9% were used. The melting was performed under the protection of inert gas - argon in an induction furnace. The liquid alloy was poured into a copper mold. In order to make amorphous ribbons, the obtained samples in the form of rods were re-melted on a melt spinner machine. The next step was to perform corrosion tests in Ringer's solution. Corrosion tests were carried out at a temperature of 37°C and pH 7.2. The purpose of using Ringer's solution was to recreate the conditions for the body fluids of the human body. The use of the following research methods, such as: OCP (open circuit potential), LSV (linear sweep voltammetry) and EIS (electrochemical impedance spectroscopy), was aimed at determining the corrosion resistance of the tested materials. Tests carried out in Ringer's solution showed that pure magnesium has significantly worse corrosion resistance than the binary Mg72Zn28 alloy. The conducted research also confirmed that the cathodic reaction takes place faster on the surface of amorphous ribbons. It was also confirmed that for both crystalline materials there is diffusion of chloride ions through the corrosion product layer. SEM-EDS tests were performed on the surface of an amorphous ribbon of the Mg72Zn28 alloy after corrosion in Ringer's solution.

Double-Win Properties Response of Mechanical and Hydrogen Absorption in Melt-Spun Ti-Zr-Ni-Cr Amorphous Metals

The effect of spinning rates on mechanical properties and hydrogen absorption/desorption properties of Ti47Zr31Ni14Cr8 amorphous ribbons have been investigated in the present work. A fully amorphous structure was confirmed by x-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis of the ribbons obtained from spinning rates of 30 m s−1 to 45 m s−1. The uniformity of amorphous ribbons and their mechanical properties were improved with the increase in the spinning rate. Scanning electron microscopy (SEM) revealed that the fracture surface of amorphous ribbons had a cleavage feature and vein-like pattern when the spinning rates were 30 m s−1 and 45 m s−1, respectively. Because of the influence of flow units on the kinetic process of hydrogen absorption, the hydrogenation kinetics and hydrogen desorption capacity of amorphous ribbons were enhanced with the increased spinning rates. After the amorphous ribbons absorbed a large amount of hydrogen, ZrH2, TiH2, and (ZrTi)2Ni7 crystalline phases were formed from the amorphous matrix. Hydrogen promotes amorphous phase decomposition and the crystallinity of the new phases led to deterioration of the mechanical properties.

Tunable Mechanical Properties of Ti-Zr-Ni-Cr Amorphous Ribbons via Vanadium Addition

In this paper, the effects of vanadium addition on the mechanical properties of Ti-Zr-Ni-Cr amorphous ribbons with high spinning speed were studied. It was found that the mechanical properties of samples were obvious promoted by adding vanadium into Ti-Zr-Ni-Cr amorphous alloys. The rapidly solidified Ti-Zr-Ni-Cr (V = 0, V = 0.1) ribbons at a speed of 45 m/s is an amorphous structure. But the amorphous structure of Ti-Zr-Ni-Cr-V alloys is even more uniform than that of the V-free alloys samples. In particular, Ti-Zr-Ni-Cr-V amorphous ribbons showed better mechanical properties that the tensile strength (\(\sigma_{b}\)) of the amorphous ribbons samples that had been significantly increased from 542 MPa for V = 0–675 MPa for V = 0.1. The elongation (δ) exhibited a tiny increase from 1.1% for V = 0–1.29% for V = 0.1. The fractured surface of amorphous ribbons for V = 0 showed more cleavage features, it was the obviously brittle fracture. The fracture surface for amorphous ribbons for V = 0 were more vein-like patterns, they are attributed to a local change of viscosity. It’s likely that adding V into Ti-Zr-Ni-Cr amorphous alloys is beneficial to enhance rheological units and massive accumulation of free volume in ribbons. It contributes to mechanical properties, especially for the tensile strength and the plastic deformation of the amorphous ribbons.

Corrosion performance of melt-spun Mg67Zn28Ca5 metallic glass in artificial sweat

The Mg-based metallic glass developed in this study provides an alternative for Mg alloys for being used in daily life. In this study, the corrosion behaviors of melt-spun MgZnCa ribbons with and without heat treatment were investigated in artificial sweat. Surface morphology analysis showed that amorphous ribbon was more sensitive to suffer from pitting corrosion. Electrochemical testing and measurement of metal ion concentrations indicate that ribbons in amorphous structure were nobler with smaller corrosion current and possessed much slower dissolution rate of metal ions. A Zn-rich passivation layer is detected on the surface of amorphous ribbon, indicating that Zn is more effective in amorphous ribbon to protect the inner active metal.

Periodically Laser Patterned FeBSi Amorphous Ribbons: Phase Evolution and Mechanical Behavior

AbstractThe properties of amorphous alloys are significantly influenced by structural relaxation and partial/full crystallization induced by thermal annealing of the alloy. In this paper, the phase evolution and mechanical behavior of laser‐patterned FeBSi amorphous alloys are reported. The laser patterning was employed to cause localized thermal effects on the surface of amorphous ribbons. The laser irradiation with a lower fluence (12 J · cm−2) caused significant embrittlement of the alloy due to the structural relaxation. The partial crystallization of an amorphous alloy into α‐Fe(Si) was also observed with laser irradiation using higher laser fluences (15 and 17 J · cm−2). The embrittlement effect due to laser‐irradiation‐induced crystallization was more severe than that due to structural relaxation.

Atomic-scale scanning tunneling microscopy of amorphous surfaces

Surfaces of amorphous metals are studied by scanning tunneling microscopy (STM). In situ prepared surfaces of amorphous ribbons and splats as well as thin $(l5 \mathrm{nm})$ films show a characteristic morphology that is attributed to the amorphous state. STM images allow us to clearly distinguish the amorphous and crystalline state as evidenced by experiments where the same sample is imaged in both states of order. True atomic resolution in the sense that the positions of all surface atoms can be derived from the data is not obtained, although the images contain regions where atom-sized features appear. Two reasons for this laterally nonuniform resolution capability are discussed: (i) the geometrical hiding of lower-lying atoms and (ii) lateral variations of the electronic structure. Both are intrinsic for amorphous surfaces. Hence, STM images do not allow a straightforward real-space structure determination of amorphous surfaces. Thick vapor-quenched amorphous films look significantly different due to kinetic roughening occurring during the growth.

An X-ray photoelectron spectroscopy study of the surface composition of Co xFe 80− xSi 10B 10 metallic glasses

X-ray photoelectron spectroscopy (XPS) was used to analyze native oxide films at the surfaces of amorphous ribbons of Co x Fe 80− x Si 10B 10 ( x=0, 15, 70, 80). The oxide layer differs in thickness and composition for the different samples, but no difference in thickness is detected for the shiny and dull sides of each ribbon, even if different chemical compositions are found. A large surface segregation of silicon is observed for the whole set of compositions. Boron has a qualitatively similar but quantitatively less pronounced surface segregation. Iron oxides are also included in the passive films while cobalt, strongly depleted at the surface, is present mainly in the non-oxidized form. XPS data were compared with the results of corrosion tests obtained by immersion of the ribbons in acidic solutions of different pH.

Magnetization processes in amorphous ribbons influenced by electrical current in the ribbon

Measurements of hysteresis loops and derivatives of magnetization with time versus applied field have been performed on amorphous Fe- and Co-based ribbons with a current flowing along the ribbon. Experiments have also been performed with aluminum foils glued onto surfaces of amorphous ribbons, with current passing through them.

Preparation, power loss and domain structure of electropolished amorphous ribbons

The optimum conditions and electrolyte for the electropolishing of three types of amorphous ribbon have been found. It has been found that the power loss of amorphous ribbons is affected by electropolishing and that electropolishing can be used to reduce the power loss of materials with zero magnetostriction. It has not been found possible to stress-relief anneal electropolished samples of materials whose magnetic properties are stress-sensitive. The electropolishing technique is to be preferred to mechanical polishing as a means of smoothing the surface of amorphous ribbons. The domain structures of the electropolished amorphous ribbons have been observed using the Kerr magnetooptic technique.

双ロール法により製造した非晶質合金薄帯の厚さの不均一性について

Many cavities originating from air bubbles exist on the bottom surfaces of amorphous ribbons made by the single roller method. These cavities have an injurious effect on the degree of surface fineness of the ribbons.Amorphous ribbons with uniform surface are required for the purpose of application. Therefore, the double roller quenching method was investigated to make uniform amorphous ribbons.A house-made double roller apparatus with rolls 100 mm and 120 mm in diameter was used. Roll pressure was controlled by oil-pressure. Nozzles are made of quarts with single hole or multiple holes. The surface temperature of the roll was measured during the melt-ejection. Puddle formation by the melt jet on the roll surface was observed by a high-speed movie print. The relation between manufacturing variables and the non-uniformity of thickness was examined. Any cavities do not occur with the double roller method because of the roll pressure. Thus it is expected that if the roll surface is fine, ribbons with uniformity may be obtained with the double roller method.It has been found that the thermal expansion of the rolls is not a main cause of the non-uniformity of thickness. It is considered that the non-uniformity of thickness is caused by the difference in the reduction rate along the width of the roll resulting from the temperature distribution in the melt puddle.

Magnetic anisotropy distribution near the surface of amorphous ribbons

Magnetic anisotropy in an amorphous ribbon of Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">40</inf> Ni <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">40</inf> P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</inf> B <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> has been studied. Domain structures and the in-plane anisotropy were measured as a function of the depth from the ribbon surface by a powder technique, transmission electron microscopy and a torque method. Groups of fine domains diminish with depth. The maximum in-plane anisotropy exists at the surface and the anisotropy decreases one or two orders in magnitude at the center of the ribbon. The data have an obvious connection with the surface topography of the ribbon that is introduced in the melt and quench process.