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In this paper, using Monte Carlo simulations (MCSs) under the metropolis algorithm, the authors study the magnetic properties of the yttrium-based Heusler alloys: Y₂CrGa and YFeCrGa. In the first step, the authors elaborate and discuss the ground-state phase diagrams of the more stable configurations. It is worth to note that the full-Heusler alloy Y₂CrGa contains only one magnetic atom (Cr), while the quaternary Heusler alloy YFeCrGa has two magnetic atoms (Cr and Fe). This leads to modeling of the compound Y₂CrGa by a Hamiltonian containing only one magnetic spin moment (S = 2), while the quaternary Heusler alloy YFeCrGa is modeled by a Hamiltonian containing two magnetic spin moments (Q = 5/2 and s = 2). The results of the study reveal that the critical temperature increases when increasing the reduced crystal field for the two studied compounds. To complete this study, the authors elaborated the hysteresis cycles of the two yttrium-based Heusler alloys: Y₂CrGa and YFeCrGa.

In this paper, the authors study the magnetic properties and the critical behavior of the yttrium-based Heusler alloys, Y₂CrGa and YFeCrGa, using MCSs under the metropolis algorithm. In the first step, the authors elaborate and discuss the ground-state phase diagrams of the more stable configurations for the both structures at null temperature (T = 0). On the other hand, for non-null temperature (T ≠ 0), the authors investigate the critical behavior of these two yttrium-based Heusler alloys: Y₂CrGa and YFeCrGa. It is worth to note that the full-Heusler alloy Y₂CrGa contains only one magnetic atom (Cr), while the quaternary Heusler alloy YFeCrGa has two magnetic atoms (Cr and Fe). Hence, the compound Y₂CrGa can be modeled by a Hamiltonian containing only one magnetic spin moment (S = 2), while the quaternary Heusler alloy YFeCrGa is modeled by a Hamiltonian containing two magnetic spin moments (Q = 5/2 and s = 2). Moreover, the results of the study reveal that the critical temperature increases when increasing the reduced crystal field for the two studied compounds. To complete this study, the authors elaborated the hysteresis cycles of the two yttrium-based Heusler alloys: Y₂CrGa and YFeCrGa.

The authors elaborate the ground-state phase diagrams of the more stable configurations. It is worth to note that the full-Heusler alloy Y₂CrGa contains only one magnetic atom (Cr), while the quaternary Heusler alloy YFeCrGa has two magnetic atoms (Cr and Fe). This leads to modeling of the compound Y₂CrGa by a Hamiltonian containing only one magnetic spin moment (S = 2), while the quaternary Heusler alloy YFeCrGa is modeled by a Hamiltonian containing two magnetic spin moments (Q = 5/2 and s = 2). The results of the study reveal that the critical temperature increases when increasing the reduced crystal field for the two studied compounds. To complete this study, the authors elaborated the hysteresis cycles of the two yttrium-based Heusler alloys: Y₂CrGa and YFeCrGa.

The authors elaborate the ground-state phase diagrams of the more stable configurations. It is worth to note that the full-Heusler alloy Y₂CrGa contains only one magnetic atom (Cr), while the quaternary Heusler alloy YFeCrGa has two magnetic atoms (Cr and Fe). This leads to modeling of the compound Y₂CrGa by a Hamiltonian containing only one magnetic spin moment (S = 2), while the quaternary Heusler alloy YFeCrGa is modeled by a Hamiltonian containing two magnetic spin moments (Q = 5/2 and s = 2). The results of the study reveal that the critical temperature increases when increasing the reduced crystal field for the two studied compounds. To complete this study, the authors elaborated the hysteresis cycles of the two yttrium-based Heusler alloys: Y₂CrGa and YFeCrGa.

The authors elaborate the ground-state phase diagrams of the more stable configurations. It is worth to note that the full-Heusler alloy Y₂CrGa contains only one magnetic atom (Cr), while the quaternary Heusler alloy YFeCrGa has two magnetic atoms (Cr and Fe). This leads to modeling of the compound Y₂CrGa by a Hamiltonian containing only one magnetic spin moment (S = 2), while the quaternary Heusler alloy YFeCrGa is modeled by a Hamiltonian containing two magnetic spin moments (Q = 5/2 and s = 2). The results of the study reveal that the critical temperature increases when increasing the reduced crystal field for the two studied compounds. To complete this study, the authors elaborated the hysteresis cycles of the two yttrium-based Heusler alloys: Y₂CrGa and YFeCrGa.

The authors elaborate the ground-state phase diagrams of the more stable configurations. It is worth to note that the full-Heusler alloy Y₂CrGa contains only one magnetic atom (Cr), while the quaternary Heusler alloy YFeCrGa has two magnetic atoms (Cr and Fe). This leads to modeling of the compound Y2CrGa by a Hamiltonian containing only one magnetic spin moment (S = 2), while the quaternary Heusler alloy YFeCrGa is modeled by a Hamiltonian containing two magnetic spin moments (Q = 5/2 and s = 2). The results of the study reveal that the critical temperature increases when increasing the reduced crystal field for the two studied compounds. To complete this study, the authors elaborated the hysteresis cycles of the two yttrium-based Heusler alloys: Y₂CrGa and YFeCrGa.

The authors elaborate the ground-state phase diagrams of the more stable configurations. It is worth to note that the full-Heusler alloy Y₂CrGa contains only one magnetic atom (Cr), while the quaternary Heusler alloy YFeCrGa has two magnetic atoms (Cr and Fe). This leads to modeling of the compound Y₂CrGa by a Hamiltonian containing only one magnetic spin moment (S = 2), while the quaternary Heusler alloy YFeCrGa is modeled by a Hamiltonian containing two magnetic spin moments (Q = 5/2 and s = 2). The results of the study reveal that the critical temperature increases when increasing the reduced crystal field for the two studied compounds. To complete this study, the authors elaborated the hysteresis cycles of the two yttrium-based Heusler alloys: Y₂CrGa and YFeCrGa.

THE existence of compass errors on ships resulting from the presence of masses of iron in the vicinity of the compass and the method of compensating such errors have been known for over a century. In aircraft the problem is essentially similar, but an additional complication arises where there are moving masses in close proximity to the compass, as the effect of such masses in distorting the Earth's magnetic field depends on their position and therefore cannot be adequately compensated by the usual methods.

The electronic properties, exchange interactions, Curie temperatures and transport properties of random quaternary Heusler alloys (Ni, Cu)₂MnSn are studied by means of density-functional calculations over the entire range of dopant concentration. Results agree qualitatively as well as quantitatively with the available experimental data. The residual resistivity is found to obey the Nordheim rule, indicating weak-scattering regime. The temperature-dependent spin-disorder resistivity is found to be described well via the disordered model of local moments. Effect of pressure on the Curie temperature and the resistivity is also explored.

The purpose of this study is to determine the effect of current density on the surface roughness and corrosion performance of electrodeposited Co–Ni–Fe-coated mild steel. Process variables are the key factor in controlling the electrodeposition process. It is important to study the processing parameter to optimize the mechanical and corrosion resistance performance of the coating substrate.

A low-cost electrodeposition method was used to the synthesize Co–Ni–Fe coating on the mild steel substrate. In the electrodeposition, electrochemistry concept was applied. The temperature of the process was controlled at 50 ± 5°C in an acidic environment. The influence of current density (11, 22 and 33 mA/cm²) and deposition time (15, 20 and 30 min) toward the surface roughness, hardness and corrosion rate was investigated.

The increases of time deposition and current density have improved the microhardness and corrosion resistance of Co–Ni–Fe-coated mild steel. The Co–Ni–Fe nanoparticles deposited at 30 min and current density of 33 mA/cm² experienced the smallest surface roughness value (Ra). The same sample also obtained the highest Vickers microhardness of 122.6 HV and the lowest corrosion rate. This may be due to the homogenous and complete protection coating performed on the mild steel.

The findings from the study are important for future application of Co–Ni–Fe on the mild steel parts such as fasteners, car body panels, metal chains, wire ropes, engine parts, bicycle rims, nails and screws and various outdoor uses. The improvement of corrosion resistance using optimum electrodeposition parameters is essential for these applications to prolong the life span of the parts.

A new process which pertains to fabrication of Co–Ni–Fe as a protective coating on mild steel was proposed. The Co–Ni–Fe coating can enhance the corrosion protection and thus prolong the lifespan of the mild steel parts.

Passivity and localized corrosion is discussed using iron, iron‐chromium, iron‐chromium‐nickel alloys and aluminium as examples. A brief description is given of the prevailing ideas regarding the nature of the passive film and the processes by which its protective properties are lost when breakdown of passivity and localized corrosion occurs.

Introduction The passivation of iron in aqueous media has been investigated over a number of years. Bartlett and Stephenson and Froment et al. have given a deep insight into the processes of anodic depositon of FeSO4 on iron in H2SO4 solutions. Krstulonic et al. investigated the anodic passivation of Armco iron in a wide range of concentrations of suphuric avid. Alloy elements (Cr, Ni, Mo) are sometimes added to carbon steels to improve their mechanical properties and/or the effects of heat treatment. These metals can increase or decrease corrision resistance depending on the harshness of the environment. The most important alloy of stainless steel is chromium, which induces the formation of a good protective oxide film. According to the literature the alloy must contain at least 1.3 per cent chromium to form a stable passive film. The influence of chromium on the anodic dissolution of Fe‐Cr in sulphuric acid solutions has been the object of several investigations.

This chapter is intended to present the onset, evolution, and decline of Compañía Minera El Zancudo, considered the largest Colombian company in the nineteenth century. Additionally, the chapter will examine its role in both the development of manufacturing industries and the introduction of modern capitalism in the country.

The case is based on secondary information collected according to a documentary research method in which the authors selected, categorized, interpreted, and confronted different sources concerning El Zancudo.

The inception and evolution of El Zancudo involved local and foreign knowledge, techniques, and capital investments that contributed to the company growing to the point of reaching the unprecedented figure of 1,350 workers in the year 1890. Its transition from a failed local mine to a prosperous and intricate business group is full of referrals and links to foreign investment, knowledge transfer, industrial development, and an orientation toward entrepreneurship that contributed to the understanding of subsequent enterprises not only in the Antioquia region but also across the entire country.

This case study was written using limited reliable secondary sources about El Zancudo. Other significant Colombian companies in the nineteenth century (Ferrería de Pacho, Ferrería de Amagá, Empresa Textilera de Samacá, and Cervecería Bavaria) and their links to El Zancudo were mentioned but not deeply analyzed in this chapter.

The clear-cut causes that led El Zacudo to close its operations within the first decades of the twentieth century are worthy of discussion, not only by scholars and business practitioners, but also by policy makers in order to understand the phenomenon and possibly prevent existing companies from failing in a similar manner.

This case brings together the scattered literature on El Zancudo and analyzes the drivers and consequences of both its rise and fall, taking into consideration the specific historical, political, and economic contexts, furthermore, it establishes some linkages between this case and other companies under similar situations.

This investigation aims to find the degree of passivation required to completely inhibit the stress corrosion cracking of carbon steel exposed to CO-CO₂-H₂O environments.

A516 pressure vessel steel was exposed to distilled water with 25 per cent CO and 75 per cent CO₂ at an overall pressure of 800 kPa with the introduction of potassium bichromate as an additional inhibitor. Slow strain-rate tests were performed to evaluate the steel for sensitivity to cracking. Electrochemical characteristics were investigated in parallel in order to determine the extent of passivation required with the addition of the inhibitor.

Slow strain-rate tests showed that between 100 and 1,000 ppm potassium bichromate was required to completely mitigate cracking with a significant reduction in passivation current densities.

The chosen inhibitor is not ideal for practical applications as an inhibitor, but gave an indication of the passivation required.

The results showed that the added inhibitor might even cause increased sensitivity to cracking in this environment, with significant passivation required for resistance to cracking.

The degree of passivation required for complete resistance of carbon steel in 25 per cent CO-75 per cent CO₂-H₂O.

The purpose is to calculate the change in the total energy of a small fragment of an idealized lattice of iron (in its pure form and with impurity atoms) containing an edge dislocation during its elementary motion at one interatomic spacing, both under the influence of a constant magnetic field and without it. The introduction of a magnetic field into the system is aimed at checking the adequacy of the description of the phenomenon of magnetoplasticity by changing the total energy of the atomic system.

The design procedure is based on a quantum-mechanical description of the switching process of the covalent bond of atoms in the dislocation core. The authors used the method of density functional theory in the Kohn-Shem version, implemented in the GAUSSIAN 09 software package. Using the perturbation theory, the authors modeled the impact of an external constant magnetic field on the energy of a system of lattice atoms.

The simulation results confirmed the effect of an external constant magnetic field on the switching energy of the covalent bond of atoms in the dislocation core, and also a change in the magnetic susceptibility of a system of atoms with a dislocation. This complements the description of the magnetoplastic effect during the deformation of metals.

The authors created quantum-mechanical models of the dislocation motion in the Fe crystal lattice: without impurities, with a substitutional atom Cr and with an interstitial atom C. The models take into account the influence of an external constant magnetic field.

This study attempts to investigate corrosion inhibition properties of 1H-benzimidazole (B) and 1H-benzotriazole (BTA) on aluminum in 0.25 M HCl solution at different concentrations.

To this end, electrochemical techniques including electrochemical noise (EN), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used.

Results showed a greater corrosion inhibition efficiency of BTA than B on aluminum in HCl solution. BTA showed greater tendency to adsorption on the metal surface than B because of the inclusion of three nitrogen atoms.

The novelty of this work is comparing EN data with EIS and potentiodynamic polarization parameters.