Arc Melting Method Research Articles

Studying the Effect of Praseodymium Pr Substituted Nd<sub>2</sub>Fe<sub>14</sub>B Alloys on its Magnetic Anisotropic Properties Prepared by Arc Melting

Nd2Fe14B permanent magnet manufacturing technology in some developing countries is still relatively difficult because it is constrained by limited equipment facilities and dependence on imports of raw materials. In the context of efforts to build national independence, the concrete step is to try to study the process of making permanent Nd2Fe14B magnets with conventional facilities and technology. In this research an attempt was made to make and characterize Nd2Fe14B permanent magnets substituted with praseodymium Pr metal using conventional technology through the arc melting method. The success parameter of the results of this sample making is the formation of the Nd2Fe14B phase in the sample. The formation of this phase can be fundamentally studied the number of mass fractions of formed phases and structure crystallography using X-ray diffraction facilities and is supported by spectroscopy facilities and their magnetic properties. So the purpose of this research in general is to study the manufacturing process and the fundamental formation of the phases of the NdPrFe14B sample making through the arc melting method, while specifically wanting to know the relationship between phase analysis and the magnetic anisotropic properties of NdPrFe14B. The coercivity field appears to increase significantly after the sample is substituted with Pr and has a fairly small crystallite size distribution. So it was concluded that the presence of Pr was able to withstand the growth of grain, causing the anisotropic magnetocrystalline field to increase.

Effect of Ce on phase formation and magnetic properties of (Nd–Pr)2.28Fe13.58B1.14 melt-spun ribbons

The phase formation of the (Nd0.70Pr0.30−xCex)2.28Fe13.58B1.14 (x = 0.10, 0.15, and 0.20; hereafter defined as Pr20Ce10, Pr15Ce15 and Pr10Ce20, respectively) and (Nd0.60Pr0.40−yCey)2.28Fe13.58B1.14 (y = 0.10, 0.20, and 0.30; hereafter defined as Pr30Ce10, Pr20Ce20 and Pr10Ce30, respectively) alloys that were prepared via the arc-melting method was investigated experimentally. The x-ray diffraction results revealed that all alloys annealed at 1173 K for 360 h consisted of a (NdPrCe)2Fe14B main phase with a tetragonal Nd2Fe14B-typed structure (space group P42/mnm) and an α-Fe minor phase, except for the Pr10Ce30 alloy, which contained an additional CeFe2 phase. The magnetic properties of the (Nd0.70Pr0.30−xCex)2.28Fe13.58B1.14 and (Nd0.60Pr0.40−yCey)2.28Fe13.58B1.14 ribbons that were prepared by melt spinning were examined. The remanence (Br) and maximum magnetic energy product ((BH)max) of the (Nd0.70Pr0.30−xCex)2.28Fe13.58B1.14 ribbons increased first and then decreased, whereas the coercivity (Hcj) of the ribbons increased with an increase in Ce content. The Br and (BH)max of the (Nd0.60Pr0.60−yCey)2.28Fe13.58B1.14 ribbons increased, whereas the Hcj of the ribbons decreased gradually with an increase in Ce content. This changed behavior of magnetic properties is attributed to the variation of volume fraction of the α-Fe phase and different phase formations in the melt-spun ribbons. The Curie temperatures (Tc) of all ribbons decreased slightly with Ce substitution, which results from the lower Curie temperatures of Pr2Fe14B and Ce2Fe14B. The Pr10Ce30 ribbon with a higher Ce content exhibited optimal magnetic properties (Br = 9.71 kGs, Hcj = 13.09 kOe, (BH)max = 18.78 MGOe), which indicates that suitable magnetic properties of the Nd–Pr–Ce–Fe–B melt-spun ribbons can be achieved by alloy-composition and phase-formation design.

Decoupling of itinerant and localized d-orbital electrons in the compound Sc0.5Zr0.5Co

By using the arc-melting method, we successfully synthesize the compound Sc0.5Zr0.5Co with the space group of Pm−3m. Both the resistivity and magnetic susceptibility measurements reveal a phase transition at about 86 K. This transition might be attributed to the establishment of an antiferromagnetic order. The magnetization hysteresis loop measurements in wide temperature region show a weak ferromagnetic feature, which suggests a possible canted arrangement of the magnetic moments. Bounded by the phase transition temperature, the resistivity at ambient pressure shows a change from Fermi liquid behavior to a super-linear behavior as temperature increases. By applying pressure up to 32.1 GPa, the transition temperature does not show a clear change and no superconductivity is observed above 2 K. The density functional theory calculations simulate the antiferromagnetic order and reveal a gap between the spin-up and spin-down d-orbital electrons. This kind of behavior may suggest that the antiferromagnetic order in this compound originates from the localized d-electrons which do not contribute to the electric conduction. Thus the itinerant and localized d-orbital electrons in the compound are decoupled.

Study of group 5B transition metal monoborides under high pressure

We report the structural stability and compressibility behavior of 5B transition metal (TM) monoborides VB and TaB under high pressure. For the study, VB was synthesized in single phase by arc melting method followed by repeated annealing treatments and intermediate grinding; and TaB was procured. High pressure X-ray diffraction studies were carried out using synchrotron X-ray radiation up to 37.5 and 40.5 GPa for VB and TaB, respectively. The ambient orthorhombic lattices were stable for the monoborides in the pressure range studied. The bulk moduli were estimated to be 301(5) and 367(4) GPa, respectively. The axial compressibility was highest along the a direction for both VB and TaB due to predominant presence of metallic TM–TM bonds and absence of covalent B–B bonds along this direction. However, the least compressibility occurred along the c axis for TaB, and along the b axis for VB. The experimental results were substantiated with ab initio electronic structure calculations and the electronic and elastic properties were studied. Both VB and TaB were metallic due to the metallic nature of TM–TM bonds. Study of the density of states (DOS) and charge density distribution revealed that the TM–B bonds exhibited both ionic and covalent nature. The charge transfer from Ta to B was greater than that from V to B. The higher bulk modulus of TaB can be attributed to the stronger B–B covalent bond and enhanced charge transfer between Ta and B. Presence of a pseudogap at Fermi level in both their DOS plots inferred high structural stability. The cause of pseudogap formation was discussed. The study of elastic properties showed that both VB and TaB were mechanically stable in the pressure range studied. Small Pugh and Poisson's ratio indicated that VB and TaB were not ductile or malleable in nature.

Room temperature magneto-caloric effect and electron transport properties study on Ni2.14Mn0.55Sb1.31 alloy

Ni2.14Mnd0.55Sb1.3 Heusler alloy has been prepared by the conventional arc melting method with vacuum-sealed annealing. The sample has been crystallized to Fm3¯m space group in L21 phase, and it is the parent crystal structure of the Ni-based Full Heusler alloy. It has been found that the sample has the Curie temperature (para to ferromagnetic transition temperature) at 290K. It was determined from magnetization ∼ temperature plot (M ∼ T) as well as by employing the Arrott plot method. Also, critical exponent analysis by employing the Arrott plot and Kouvel-Fisher methods confirm that the sample (Ni2.14Mn0.55Sb1.31) obeys mean field theory with long range spin ordering. Analysis of temperature dependent resistivity data interestingly reveals the phonon-phonon and magnon-manon scattering dominance above and below the Curie temperature, respectively. The electrical and magnetic properties investigation endorse that there is a correlation between magnetic and electrical properties of the above sample. The magnetocaloric effect (MCE) analysis is carried out by using the Maxwell’s equations in isothermal magnetization data. It is interesting to note that the sample exhibits maximum MCE near the room temperature (∼290K), i.e., the magnetic Curie temperature. Hence the present alloy may be a potential material to be used for magnetic refrigeration application.

Precipitation of Titanium in Titanium Carbide Particles Dispersed in Titanium Matrix Composites Synthesized from Ti–C–N System Powder Mixtures Using Arc-Melting Method

Precipitation of Titanium in Titanium Carbide Particles Dispersed in Titanium Matrix Composites Synthesized from Ti–C–N System Powder Mixtures Using Arc-Melting Method

Phase Structure, Microstructure, and Magnetic Properties of (Nd-Ce)13.4Fe79.9B6.7 Alloys

Phase structure and microstructure of (Nd1-xCex)13.4Fe79.9B6.7 (x = 0.0–1.0) alloys that were prepared via the arc-melting method were studied experimentally in this work. The results reveal that (Nd1-xCex)13.4Fe79.9B6.7 alloys annealed at 1173 K for 360 h are a single (NdCe)2Fe14B phase with the tetragonal Nd2Fe14B-typed structure (space group P42/mnm). The formation of continuous (NdCe)2Fe14B solid solution phase in annealed (Nd1-xCex)13.4Fe79.9B6.7 alloys was confirmed. On the other hand, magnetic measurements exhibit that the coercivity, remanence, maximum magnetic energy product, and Curie temperature of (Nd1-xCex)13.4Fe79.9B6.7 ribbons that were fabricated by melt spinning technology decrease gradually with increasing Ce content, which results from the substitution of Nd by Ce in Nd2Fe14B phase due to inferior intrinsic magnetic properties of Ce2Fe14B phase.

Enhancement of hydrogenation kinetics and thermodynamic properties of ZrCo1−xCrx (x = 0−0.1) alloys for hydrogen storage**Project supported by the National Natural Science Foundation of China (Grant Nos. 21573200, 2017YFE0301505, 21601165, 21401173, 21573200, and 51731002).

The vacuum arc melting method was used to prepare ZrCo1 − xCrx (x = 0, 0.025, 0.05, 0.075, 0.1) alloys. Afterward, the crystal structure, hydrogenation kinetics, thermodynamic properties, and disproportionation performance of ZrCo1 − xCrx (x = 0−0.1) alloys were investigated. The x-ray diffraction spectra demonstrated that ZrCo1 − xCrx (x = 0−0.1) alloys contained ZrCo and ZrCo2 phases, and their corresponding hydrides consisted of ZrCoH3 and ZrH phases. The activation behaviors of Cr-substituted samples were significantly promoted. The activation time of ZrCo was 7715 s while that of ZrCo0.9Cr0.1 was 195 s. The improvement of kinetics can be attributed to the catalytic hydrogenation of ZrCr2. The activation energy for the hydrogenation of ZrCo was 44.88-kJ⋅mol−1 H2 and decreased to 40.34-kJ⋅mol−1 H2 for ZrCo0.95Cr0.05. The plateau pressure and width of the pressure–composition–temperature curves decreased slightly as Cr content increased. The extent of disproportionation of ZrCo was 83.68% after being insulated at 798 K for 10 h and decreased slightly to 70.52% for ZrCo0.9Cr0.1. The improvement of anti-disproportionation performance can be attributed to increase in the activation energy of disproportionation from 167.46-kJ⋅mol−1 H2 for ZrCo to 168.28-kJ⋅mol−1 H2 for ZrCo0.95Cr0.05.

Microstructure and Mechanical Properties of ZrCuSiN Coatings Deposited by a Single Alloy Target

Recently, research has been conducted on nanocomposite thin films containing new additive elements in ZrN. In this paper, a method for depositing ZrCuSiN nanocomposite coatings using a ZrCuSi single target is presented. The ZrCuSi target that was used to easily deposit a ZrCuSiN coating in a mixed gas atmosphere (Ar + N2) was produced by a simple arc melting method (casting process). The effect of the nitrogen content was investigated by depositing a ZrCuSiN coating using alloy targets at various nitrogen gas flow rates (2, 4, 6, and 8 sccm). X-ray diffraction analysis of the ZrCuSiN coatings revealed a ZrN structure with a preferable orientation (200). As the nitrogen flow rate increased, the formation of o-Zr3N4 was dominant in the ZrN formation. A nitrogen gas flow rate of 4 sccm produced a coating with optimal ZrN and a-Si3N4 coordination and maximum hardness (41 GPa). Reciprocal friction tests of all coatings and uncoated carburized SCM415 steel in a 5W30 lubrication atmosphere demonstrated that the 4 sccm coating had the lowest friction coefficient (0.002). Therefore, our method has the potential to be an alternative surface coating technique for materials used in automotive engine parts and various other wear protection applications.

Microstructure, phase composition and wear resistance of low valence electron concentration AlxCoCrFeNiSi high-entropy alloys prepared by vacuum arc melting

The low valence electron concentration (VEC) AlxCoCrFeNiSi (x = 0.5, 1.0, 1.5 and 2.0) high-entropy alloys (HEAs) were designed by the fundamental properties of the constituent elements and prepared by vacuum arc melting method. The effects of Al addition on the crystal structure and microstructure were investigated. The microhardness and wear property were also researched. The results showed that the microstructure transformed from dendritic crystal to equiaxed crystal. It was found that FCC phase gradually decreased with the increasing Al content and disappeared until in a composition of 1.0 in AlxCoCrFeNiSi HEAs. Little FCC phase was found with continuously adding Al, while the phase fraction of BCC increased from 85.0% to 91.8%, and VEC decreased from 7.00 to 6.14. The microhardness was increased gradually from 598 up to 909 HV with addition of Al from 0.5 to 2.0. It was the same of the compressive strength results, which improved from 1200 to 1920 MPa. The wear coefficient and mass loss were in line with mechanical properties evolution, which was attributed to the microstructure transformation into equiaxed crystal and the increase in BCC phase.

Superconductivity in Metal-Rich Chalcogenide Ta2Se.

The metal–metal bond in metal-rich chalcogenide is known to exhibit various structures and interesting physical properties. Ta2Se can be obtained by both arc-melting and solid-state pellet methods. Ta2Se crystallizes a layered tetragonal structure with space group P4/nmm (No. 129; Pearson symbol tP6). Each unit cell consists of four layers of body-centered close-packing Ta atoms sandwiched between two square nets of Se atoms, forming the Se–Ta–Ta–Ta–Ta–Se networks. Herein, we present magnetic susceptibility, resistivity, and heat capacity measurements on Ta2Se, which together indicate bulk superconductivity with Tc = 3.8(1) K. According to first-principles calculations, the d orbitals in Ta atoms dominate the Fermi level in Ta2Se. The flat bands at the Γ point in the Brillouin zone yield the van Hove singularities in the density of states around the Fermi level, which is intensified by introducing a spin–orbit coupling effect, and thus could be critical for the superconductivity in Ta2Se. The physical properties, especially superconductivity, are completely different from those of Ta-rich alloys or transition-metal dichalcogenide TaSe2.

Effect of Fe doping on microwave absorption performance of magnetic powder NdNi5

Soft magnetic alloy powder NdNi5-xFex (x = 0.0, 0.1, 0.3, 0.4) was prepared by vacuum arc melting, homogenization annealing and ball milling methods. The reflection loss of NdNi5-xFex powders were discussed based on the structural morphology, measured hysteresis loops and electromagnetic parameters. The lattice distortion and the saturation magnetization of NdNi5-xFex powders increase and the formant of the electromagnetic parameter moves toward the low frequency. The absorption peak of reflection loss also moves toward low frequency. In addition, the Nd–Ni–Fe alloy powder can achieve the best absorption bandwidth, and the minimum reflection loss value of 1.29 GHz and − 29.29 dB, respectively, with the addition of Fe content is 0.1. Add Fe content appropriately, and adjusting the thickness can effectively improve the absorbing performance of the material in c-band, so the powder has a good application prospect in c-band.

Twins and polytypic stacking faults in the ν phase formed in rapidly quenched Mn-Si alloys

Mn-rich Mn-Si binary alloys containing the ν phase have been prepared by arc-melting and rapid-quenching methods. In comparison, twins and polytypic stacking faults (SFs) are observed in the rapidly quenched ν phase, and the atomic-scale structure properties of twins and SFs have been determined by using aberration-corrected scanning transmission electron microscopy techniques. Both twins and SFs break the crystallographic symmetry of the ν phase, and lead to reconstruction of the subunits of the ν phase at twin boundaries and SFs. On the basis of experimental results, new structural models are proposed to explain the twin and SFs formation in the rapidly quenched ν phase.

Lower temperature of the structural transition, and thermoelectric properties in Sn-substituted GeTe

GeTe is a potential thermoelectric material for mid-temperature range applications. Here, we report on GeTe and Ge0.9Sn0.1Te prepared using a fast and simple arc-melting method. Their crystal structures have been analyzed by synchrotron X-ray diffraction. Calorimetry identified a shift in the rhombohedral to cubic structural transition temperature from 700 K to 557 K due to Sn alloying. Nevertheless, the temperature of the maximum Seebeck-coefficient is preserved, at 770 K. The thermoelectric properties are also reported, with a strong decrease of electric and thermal conductivities of the Sn-doped compound, as compared to the undoped one. The Hall-mobility also decreases strongly upon doping.

Experimental and Theoretical Investigation of Origin of Mechanical Properties and Fracture Mechanism of Pt3Zr High-Temperature Material

Pt3Zr is a promising high-temperature material. However, its mechanical properties and fracture mechanism are unknown. Pure Pt3Zr was prepared by the arc-melting method, and its mechanical properties and microstructure were measured by universal tester and scanning electron microscopy, respectively. In particular, its fracture mechanism was studied by first-principles and molecular dynamics (MD) methods. The measured fracture stress was 150.1 MPa. The experimental results revealed predominant cleavage fracture behavior. Although first-principles calculations showed that it is a ductile material due to the formation of symmetrical Pt-Zr bonds, the MD simulation results demonstrated that the fracture behavior of Pt3Zr can be attributed to the coalescence of numerous voids at high temperature, which is consistent with the experimental results.

Synthesis, structure and physical properties of new intermetallic spin glass-like compounds RE2PdGe3 (RE = Tb and Dy)

New intermetallic compounds Tb2Pd1.25Ge2.75 and Dy2Pd1.25Ge2.75 have been synthesized using the arc-melting method. The crystallographic structure and magnetic, electronic transport, and thermal properties are reported. The crystal structure obtained from powder x-ray diffraction analysis suggests that these compounds crystallize in the AlB2-type structure (space group P6/mmm, no. 191) with lattice parameters a = 4.228 53(5)/4.230 54 (2) Å and c = 3.942 25(9)/3.945 52(5) Å for the compounds with Tb and Dy respectively. The ac and dc magnetic susceptibility studies reveal spin-glass like behavior, with freezing temperature Tf = 10.5 K for Tb2Pd1.25Ge2.75 and 4.5 K for Dy2Pd1.25Ge2.75. These data are in good agreement with the heat capacity measurements.

Effects of melting parameters and quartz purity on silica glass crucible produced by arc method

In photovoltaic industry, silica crucible has an important influence on the quality of single crystal silicon. To obtain a silica glass crucible with large diameter, high uniformity, and low bubble content, two series of crucibles were prepared by the arc melting method, one with various melting parameters (initial power, melting power, and melting time) and crucible sizes, and the other with various quartz purities. The bubbles inside the crucible wall and pores on the inner surface were all measured using a polarised optical microscope and a portable microscope. The results show that all crucibles have a bubble aggregation area in their inner surface (0–0.4 mm), in which the density and size of bubbles are affected by melting time, melting power, and the distance between the crucible and the graphite electrode. The uniformity of the crucible decreases as the crucible diameter increases (16–28 inches), and the crucible is relatively stable when the initial power is below 400 kW. In final, a silica crucible with large size (diameter of 28 inches) and low bubble content on inner surface (∼50% reduction than that of traditional crucibles) was successfully prepared, which is of great value to the photovoltaic industry.

Influence of the Nb Content on the Microstructure and Phase Transformation Properties of NiTiNb Shape Memory Alloys

NiTi shape memory alloys (SMAs), as smart materials, are broadly used in medical implants and appliances despite the presence of toxic Ni. In this study, NiTiNb alloys were produced using the substitution of biocompatible Nb instead of Ni. The arc-melting method was utilized to make five SMA samples comprising Ni(29−x)Ti50Nb(21+x) (x = 0, 1, 2, 3, and 4); then, the phase transformation temperatures, microstructures, crystal structures, and chemical compositions were investigated by DSC, optical microscopy, XRD, and EDX measurements, respectively. The DSC results showed that the samples had a wide hysteresis with the B19′↔B2 phase transformation and martensite start temperatures below room temperature, which makes them suitable for superelastic implants. The presence of dissolved Nb in the matrix of the alloys was the main reason for the widening of temperature hysteresis. When the XRD and SEM results were examined, the β-rich, B2, B19′, and Ti2Ni phases were observed in all samples. Additionally, the main constituent in the dendritic microstructures was Nb.

Structural, Magnetic and Magnetocaloric Properties of Co2Y1−xCux (x = 0.00, 0.05, and 0.10) Compounds

We investigate the structural, magnetic, and magnetocaloric properties of the intermetallic Co2Y1−xCux (x = 0.00, 0.05, and 0.10) compounds prepared by arc melting method. The X-ray diffraction measurements show that all compounds crystallize in a cubic MgCu2-type structure with Fd-3m space group, in which the lattice parameter decreases with increasing Cu concentration. The magnetic properties of Co2Y were found to strongly depend on Cu substitution. The Curie temperature increases with increasing Cu content. In addition, the magnetic entropy change (−ΔSM) and the relative cooling power (RCP) increase with increasing Cu content. Our results highlight that Co2Y0.9Cu0.1 exhibits a second-order magnetic phase transition around room temperature with only a small magnetocaloric effect.

Controllable magnetic transitions and magnetocaloric effect of Ho1-xTmxNi (0≤x≤0.8) compounds

Polycrystalline Ho1-xTmxNi (0≤x≤0.8) compounds were successfully prepared by an arc-melting method, and the crystal structure, magnetic properties and magnetocaloric effect (MCE) were investigated in detail. X-ray diffraction (XRD) results indicate that Ho1-xTmxNi (0≤x≤0.8) compounds are pure phases with FeB-type orthorhombic structure (space group Pnma). Magnetic measurements show that HoNi alloy undergoes a spin reorientation (SR) transition and a ferromagnetic (FM) to paramagnetic (PM) transition at 13.5 K and 35.5 K, respectively. Rare earth atoms Tm with small spin were used to substitute Ho atoms in HoNi compound in order to adjust the magnetic phase transitions and to further optimize the magnetocaloric effect (MCE). With increasing Tm content from 0 to 0.8, the refrigerant temperature span decreases from 41.6 K to 17.3 K. When the content of Tm is 0.3, a platform-shaped isothermal magnetic entropy change (-ΔSM) curve is obtained and the value of -ΔSM is relatively stable over 35 K. Our findings are of great importance for HoTmNi compounds in practical applications.