Types Of Amorphous Alloys Research Articles

Prediction of phase selection of amorphous alloys and high entropy alloys by artificial neural network

To avoid the lack of unified physical significance of the random combination of characteristic parameters, and to solve the problem that there are many factors influencing the phase selection by multiple parameters, four characteristic parameters with potential energy distribution were selected to predict the phase selection of three type of amorphous alloys (AM), solid solution alloys (SS) and high entropy alloys containing intermetallic compounds (IM) by artificial neural network (ANN) in machine learning. To improve the prediction accuracy, the combination of three different parameters can be used to predict the phase of AM and IM alloys, and the combination of four different parameters can be used to predict the phase of SS alloys. For the AM and IM alloys, the partial three parameter combinations with the lowest mean square error (MSE) values have highest prediction accuracy, for SS alloys, the four parameter combination with the lowest MSE value has highest prediction accuracy. Based on the correspondence between the correlation coefficient (R) values and the prediction accuracy, it can be concluded that the current ANN model is accurate in predicting the phase selection of three type of alloys, and is the good learning model. The sensitivity matrix (S) values indicate that the atomic size difference (δ) have a greater impact on the phases of AM, SS and IM alloys; however, the corresponding S values of mixing enthalpy (ΔHm) in the AM and SS alloys have the weak influence. The current learning model and the combination of three or four characteristic parameters can predict the AM and SS phase varified by X-ray diffraction of new Ti-Cu-Ni-Zr (AM) and Fe-Co-Ni-Cu-Ti (SS) alloys, thus accelerating the composition design and phase composition selection of new alloys.

Study of a 18-Pulse Transformer–Rectifier Unit with an Amorphous Steel Magnetic Core

This article discusses a study of transformer–rectifier units with a magnetic core made of amorphous steel. Transformers with various types of amorphous alloys have been analyzed, and the optimum amorphous alloy for transformers was determined. Thermal processes in transformers with magnetic core of amorphous steel have been simulated, and the maximum temperature under normal operating conditions has been determined. The simulation has demonstrated that no special transformer cooling system is required. An experimental transformer–rectifier unit has been designed and manufactured with a magnetic core of amorphous steel installed on an 18-pulse rectifier with a capacity of 10.5 kV A operating with a frequency of 400–800 Hz and voltage of 115/27 V. To verify the obtained data, experimental studies have been performed that confirmed the validity of the selected design procedure of a transformer engineering flowchart. It has been demonstrated that the thermal loads detected in the transformer during testing are in the range of allowable values.

18-Pulse Transformer Rectifier Unit with an Amorphous Magnetic Core for Aircraft

This paper deals with a transformer-rectifier unit with a magnetic core made of amorphous steel. Transformers with various types of amorphous alloys have been compared. The most optimal amorphous alloy to use in a transformer is determined. The simulation of the electromagnetic and thermal processes occurring in transformers with a magnetic core made of amorphous steel was carried out, the amplitude and shape of the voltage and current were determined and the maximum temperature in nominal operating mode was defined. The dependencies of the specific losses in the studied samples of amorphous steel on the frequency of magnetization reversal, magnetic flux density and temperature were obtained. An experimental layout of a transformer rectifier unit with a magnetic core made of amorphous steel, loaded onto an 18-pulse rectifier with a power of 10.5 kVA and operating at a frequency of 400-800 Hz with a voltage of 115/27 V was designed and manufactured. An experimental study was carried out on the developed layout to verify the obtained data. The experimental studies confirmed the correctness of the chosen design methodology and of the design scheme of the transformer. It is important to note that the thermal loads detected on the transformer during its testing are within the permissible values.

Reduction of idling losses of eighteen-pulse transformer rectifier unit for aerospace application

This paper considers a method of reducing idling losses with the use of amorphous steel for a magnetic core for an eighteen-pulse transformer rectifier unit for the aerospace application. Numerical calculations of transformer rectifier units with various types of amorphous alloys were carried out to determine the mass and overall dimensions and idling losses. To determine the shape, amplitude and harmonic composition of the eighteen-pulse rectifier, an imitation simulation of a three-to-nine-phase rectification system was carried out. In order to determine the maximum temperatures with a nominal mode, a computer simulation of the thermal fields of the transformer rectifier unit was carried out. To verify the numerical calculations, simulation and computer simulations, experimental studies were carried out on the developed demonstration layout.

The relation of mechanical properties and local structures in bulk Mg54(Cu1−xAgx)35Y11 metallic glasses: Ab initio molecular dynamics simulations

Understanding the correlation of deformation and local structures in bulk metal glasses (BMGs) is essential for the developing new types of amorphous alloys and their engineering applications. We investigate the relation of local structures and mechanical properties for Mg54(Cu1−xAgx)35Y11 (0<x⩽0.5) alloys by combining ab initio molecular dynamics simulations with density functional theory calculations. It is found that local structures defined by the common-neighbor analysis and mechanical properties display a development as a function of composition, and the calculated results with respect to the Ag composition is well consistent with experiments. We show a strong interplay between local structures and mechanical properties in that high icosahedral ordering and low free volume are helpful to improve the strength, while the incorporation of crystalline ordering and high free volume can initiate a better intrinsic plasticity. Physical implications of these results are discussed and our research is of great value to the development of multi-components amorphous alloys.

Single-factor dispersional analysis in selecting the type of amorphous alloy and its heat treatment

80 1 Amorphous alloys cannot be used in practice without stabilization of the amorphous state—in particular, without heat treatment. Thus, annealed 71KNSR, 84KSR, and 10-020 amorphous alloys are used in the manufacture of broad-band magnetic heads, whose use in digital recording equipment increases the density and accuracy with which electroacoustic signals are recorded [1, 2]. Correct choice of the amorphous alloy and the annealing conditions is important in order to obtain magnetic and mechanical properties that correspond to the required operating parameters of the magnetic head and minimize the anisotropy of the amorphous tape and also so as to optimize the stability of the amorphous state with respect to time and temperature. As a rule, experimental data are used to select the optimal type of amorphous alloy for the recording head and optimal heat treatment, although it is also possible to use monofactorial dispersional analysis based on regression models, as will be shown in the present work. This method involves randomization of the 1 This article will be of interest primarily to those who develop and apply amorphous magnetic alloys. It employs statistical methods for optimization of the physical properties of the amorphous alloy and for harmonization of the alloy with a magnetic recording head. The article is practically overloaded with statistical calculations, but the editors have chosen to leave the text largely intact, because dispersional analysis is useful not only in the problem here presented but in many areas of metallurgy, physical metallurgy, and economics. For more details on these methods (including multifactorial dispersional analysis, extremal experiment planning, randomization strategies, and methods of information reduction), which were basically developed between 1960 and 1970, consult: Nalimov, V.V., Teoriya exksperimenta (Experiment Theory), Moscow: Nauka, 1971; Hutson, A., Dispersional Analysis (Russian translation), Moscow: Statistika, 1971. Such methods have been successfully employed in the analysis and monitoring of metals and alloys, the evaluation of chemical, metallurgical, and economic processes, and the development of mathematical models of these processes. See, for example: Shvarts, S.A., Prilozhenie matematicheskoi statistiki k analizu protsessov koksokhimicheskogo proizvodstva (Applying Statistics to the Analysis of Coke Production), Khar’kov: Metallurgizdat, 1962; Nalimov, V.V., Statisticheskie metody opisaniya khimicheskikh i metallurgicheskikh protsessov (Statistical Description of Chemical and Metallurgical Processes), Moscow: Metallurgiya, 1963. Mathematical methods prove extremely useful also in the development and prediction of new metallic materials. See, for example: Molotilov, B.V. and Matorin, V.I., Design Principles for New Functional Materials, Stal’ , 2004, no. 8, pp. 92‐94. results of annealing and their division into blocks, which allows the inclusion of the unknown systematic errors among the random errors, to which the laws of probability theory and statistics may be applied [3]. The results of annealing are divided into blocks so that all the levels of the given factor fall within each block, and the values within the block are randomized. The number of instances of annealing is determined by the number m of levels of the factor (magnetic permeability) and the number n of parallel measurements. To select three types of amorphous cobalt alloys that will ensure acceptable magnetic properties of the recording head, we consider annealing at 300 ° C in different media: air, vacuum, hydrogen. Thus, the number of blocks k = 3 (Table 1). Calculation of the sums required to determine the dispersion is based on the formulas Substituting in the numerical values, we obtain S 1 = 10 4 (0.011 + 0.0159 + 0.007056 + 0.0144 + 0.00746 + 0.016796 + 0.0096 + 0.0061 + 0.01383 + 0.054 + 0.007056 + 0.01016 + 0.0057 + 0.0045 + 0.0059 + 0.0092 + 0.0048 + 0.0175 + 0.00915 + 0.0039 + 0.00885 + 0.00348 + 0.0063 + 0.0089 + 0.00503 + 0.0397 + 0.005184 + 0.0081) = 10 4 (0.0042 + 0.0094 + 0.0054 + 0.00346 + 0.00778 + 0.003036 + 0.003036) = 0.312478 × 10 4 ; S 2 = 10 4 (0.168 + 0.187 + 0.135 + 0.107 + 0.119 + 0.0866 + 0.094 + 0.89685)/4 = 0.2242 × 10 4 ; S 3 = 10 4 (1.4617 + 0.936 + 0.822)/3 × 4

An Analysis of Crystallization Process in Amorphous Alloys Using Time-Scaling Factor

We have investigated the time-scaling properties of the isothermal crystallization process for Cu 66 Ti 34 and Zr 65 Cu 35 amorphous alloys by differential scanning calorimetry. Local atomic structures have also been studied by extended X-ray absorption fine structure (EXAFS) measurements. The results are discussed in comparison with the previous results obtained for metal-metalloid amorphous alloys. The time-scaling factor is defined as the time when the crystallization has reached half completion. By rescaling the time axis for each annealing temperatures, the crystallization curves measured at various temperatures for each alloy can be superimposed on a single curve in each case. The Williams-Landel-Ferry formula based on a free-volume consideration gives a universal function for the temperature dependence of the time-scaling factor for all the alloys. This suggests that we have to take into account the relaxation process occurring in the amorphous phase during the crystallization. The WLF analysis reveals that there exists a significant difference in the temperature dependence of the scaling factor between the metal-metal and metal-metalloid amorphous alloys. From the EXAFS study, such difference is considered to be due to the local structural differences between those two types of amorphous alloys.

Spin-wave excitation and Mossbauer spectroscopy of amorphous alloys

Amorphous Fe–Co–Zr and (Fe–TM) SiB (TM=Co, Si, Mo, Nb) alloys have been studied by Mossbauer spectroscopy and magnetization measurements from 1.5 to 300 K. The results show that the magnetic properties of different types of amorphous alloys are different, which may be related to the inhomogeneous magnetic interactions in some alloys. From three different theories (spin wave stiffness relation, Handrich relation and hyperfine field distribution curve), we obtain the structure fluctuations δ, δ′ and δ″. Comparing with δ, δ′ and δ″, we can find that the value of δ coincides with one of δ′, and the similar trend exists for all of structure fluctuations, which means that the spin wave excitations of amorphous alloys are closely correlated to the structure fluctuation and the hyperfine field distributions.

Ｘ線異常散乱法による非周期物質の局所構造解析

It is hardly determined some details of the local atomic structures in multi-component non-crystalline systems by the ordinary x-ray diffraction method. I have applied the anomalous x-ray scattering (AXS) method to overcome these difficulties in the non-crystalline systems containing more than two elements. In the present paper, I will present my recent studies of the local atomic structures in a new type of amorphous alloys with an extremely wide super-cooled liquid region and of metallic complexes in Ni-Mo electroplating aqueous solutions. The usefulness of the AXS method in the studies of the non-crystalline materials will be demonstrated.

Formation of amorphous AlCr and AlMn alloy films by rf sputtering

A new type of amorphous alloy, formed in the limited composition range of about 80–90 at.% Al (AlCr) and 70–90 at.% Al (AlMn) was produced by fr sputtering under Ar atmosphere. The existence of the amorphous phase was confirmed by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. The formation of the amorphous phase is discussed in association with the intermetallic compounds (CrAl 7, Mn 4Al 11, MnAl 6, etc.) having crystallographically complex structure, which have nearly the same composition as the amorphous phase. A weak X-ray scattering halo is observed at the diffraction angle lower than of the strongest halo which characterizes the amorphous structure. The weak scattering halo, which is generated by an X-ray interference effect, is considered to be correlated to the small clusters in which a transition metal atom coordinates several Al atoms. The crystallization temperatures of the amorphous alloys are about 400 and 370°C for AlCr and AlMn samples, respectively.

The effect of electron beam current in SEM on the observed domain structure of metallic glasses

An excessive increase of the intensity of electron beam current in the scanning electron microscope may lead to a distinct change of the magnetic domain structure observed by means of type II magnetic contrast. This effect was studied on two types of amorphous alloys, one with very low and the other with a rather large positive magnetostriction. From the calculations of the heating effect of the electron beam together with the analysis of the experiments, it was concluded that the results may be explained by the local anisotropy induced by the strain distribution around the area heated by the beam, favouring a normal component of magnetization close to the surface and consequently an associated closure domain pattern.

New type of amorphous alloy; SiZnS

Hydrogenated amorphous SiZnS film was synthesized by means of radio-frequency magnetron sputtering of Si and ZnS composite target. Infrared absorption, Raman scattering, optical absorption, electron spin resonance and photoconductivity measurements were carried out for both as-deposited and annealed films. These experiments show that the structure of present SiZnS alloy films is a mixture of both the tetrahedral one due to SiSi and ZnS bonds and chalcogenide glassy one due to SiS bonds.

Transport-properties of metallic glasses at high pressures

We report on the pressure and temperature dependence of the electrical resistivity of several amorphous alloys. The pressure range covered extends from 1 bar to 130 kbar. The temperature is varied at constant pressure 0etween 1.3 K and 300 K. Data for several types of amorphous alloys will be presented. The low temperature data will be discussed in terms of superconductivity effects, the high temperature data in terms of a modified Ziman-model.

Magnetic Properties and Stability of Amorphous Alloys

After mentioning briefly the advantages and disadvantages of amorphous alloys, examples are given of possible technological applications of such alloys. The stability of amorphous alloys is of major concern in every application. Several models dealing with the stability are discussed in the light of experimental data such as the amorphous to crystalline transformation enthalpy and the activation enthalpy of this transformation.It is shown that the magnetic properties of amorphous alloys can be described properly only if account is taken of the presence of compositional short range ordering. The model proposed for the description of differences in magnetic properties between various types of amorphous alloys can successfully be used also to describe differences in magnetic properties between amorphous and crystalline materials.