Arc Melting Technique Research Articles

HTXRD based lattice thermal expansion and specific heat capacity modelling of C15-Fe2Zr Laves phase

Crystallographic phase pure C15-Fe2Zr was obtained through arc melting technique. X-ray Diffraction (XRD), scanning electron microscope (FESEM) along with energy-dispersive X-ray analysis (EDS) and differential scanning calorimetry (DSC)were employed to study the single phase in Fe-33.3at.% Zr alloy. Rietveld refinement of the high-temperature XRD patterns (from 298K-873 K) revealed the average linear and volumetric coefficients of thermal expansion of the alloys as αai= 0.3643 × 10−5 K−1 and αVi = 1.0916 × 10−5 K−1, respectively. The experimental heat capacity and enthalpy increment of the C15-Fe2Zr phase from 310K to 890K was modelled employing Quasi-harmonic Debye Grüneisen theoretical modelling by identifying the vibrational, electronic, anharmonic and magnetic contributions. Curie temperature(~625K) was determined from the magnetic contribution of the heat capacity.

Thermophysical properties of AlxCoCrCuFeNi high entropy alloys

The AlxCoCrCuFeNi (x = 0.25, 0.5, 1, 2) high entropy alloys (HEAs) were prepared by arc melting and spray casting techniques. Their microstructures, hardness, and thermophysical properties such as fusion enthalpy, entropy, thermal diffusion coefficients, thermal expansion coefficients, were investigated. XRD results indicated that AlxCoCrCuFeNi (x = 0.25 and 0.5) alloys were composed of a high-entropy FCC phase and Cu-rich nanophase. As the Al content increased to 1 and 2, the phase structures included the AlNi-rich B2 phase, FeCr-rich A2 phase and Cu-rich nanophase. With the increased Al content, the microstructures of AlxCoCrCuFeNi HEAs transitioned from coarse dendrites to petal-like dendrites, and the grains were continuously refined. Moreover, the Al additions reduced the density whereas increased the Vickers hardness of the alloys. The maximum hardness observed in Al2CoCrCuFeNi HEA was approximately 2.4 times greater than that of the Al0.25CoCrCuFeNi HEA. The thermal diffusion coefficients of alloys initially increased and subsequently decreased as the temperature elevated. The phase transformation induced by Al content was an effective method for rapidly homogenizing the internal temperature of alloys. Furthermore, the crystal structure, elemental segregation, lattice distortion, enthalpy and entropy of fusion, and lattice vibration frequency all mutually affected the thermal diffusion and expansion coefficients of AlxCoCrCuFeNi HEAs.

Magnetostructural transformation and magnetocaloric response in Mn(Fe)NiSi(Al) alloys

An efficient magnetocaloric refrigerant must have certain characteristics such as a sharp transition near the desired working temperature, a large cyclic magnetocaloric response, and the use of raw materials with reduced costs and low environmental consequences. In this sense, this work focuses on a series of rare-earth- and Co-free Mn0.5Fe0.5NiSi1-xAlx alloys (x = 0.0525, 0.060, 0.0685) with promising magnetocaloric properties. The alloys were synthesized using combined arc melting and induction melting techniques, as this synthesis route provides improved control on the sample composition and homogeneity. We investigated how the heat treatment temperature and Al content affect the magnetostructural and magnetocaloric properties of the alloys. On the one hand, it is found that annealing at 1173 K for 7 days leads to a sharp magnetostructural transformation with no traces of impurities for the alloy with x = 0.0525. Under these conditions, a large isothermal entropy change of –11.5 J kg−1 K−1 for 1 T is obtained near room temperature, significantly improving the value of the as-cast sample. On the other hand, following this optimal heat treatment, the influence of Al content is studied: upon increasing the Al concentration the magnetostructural transformation shifts to lower temperatures, ranging from 320 K for x = 0.0525 to 220 K for x = 0.0685 (measured upon heating).

Cluster-spin-glass behavior in new ternary RE2PtGe3 compounds (RE = Tb, Dy, Ho)

Abstract Two new ternary germanides Tb2Pt1.2Ge2.8, Dy2Pt1.15Ge2.85 and one already known germanium Ho2Pt1.1Ge2.9.were synthesized using an arc melting technique. The obtained samples were investigated by powder x-ray diffraction, which indicated that all of them crystallized in a hexagonal structure with P6/mmm (no. 191) space group. This structure is a disordered variant of the AlB2 aristotype that favors the formation of a spin-glass-like state. The physical properties were examined by measuring magnetic susceptibility, heat capacity and electrical resistance. Experiments indicated that all of the compounds can be classified as cluster-spin-glasses with the freezing temperature of T f = 12.0 K, T f = 6.0 K and T f = 2.9 K for Tb2Pt1.2Ge2.8, Dy2Pt1.15Ge2.85 and Ho2Pt1.1Ge2.9 respectively.

Crystal structure re-determination of binary IrAl2.75 into Ir8Al21.22

The Ir8Al21.22 binary intermetallic compound was synthesized using arc melting technique. Its crystal structure probed by single-crystal X-ray diffraction is a superstructure variant of the previously reported cubic IrAl2.75 compound. Ir8Al21.22 crystallizes in the Fmm2 space group with the unit cell parameters of a = 15.3307(9) Å, b = 15.3226(10) Å, c = 15.3129(9) Å, and V = 3597.1(4) Å3. The crystal structure contains columns of interpenetrating distorted icosahedral clusters – a characteristic feature of the approximant phases and quasicrystals. Electronic structure calculations indicate strong hybridization between valence orbitals of iridium and aluminum atoms accompanied by the formation of pseudogap, which separates the valence and conduction bands.

Metastable solidification mechanisms and micromechanical property modulations of rapidly crystallizing Si66.7Ni33.3 peritectic alloy

Metastable solidification mechanisms and micromechanical property modulations of rapidly crystallizing peritectic Si66.7Ni33.3 alloy were systematically investigated by glass fluxing and arc melting techniques. Glass-fluxed samples were undercooled up to 230 K, and the solidification microstructures consisted of Si, NiSi2 and NiSi phases. As the undercooling rose, primary Si phase grew faster along with the enhancement of volume fraction and the morphology transitioned from lamellar structure to dendritic structure. Meanwhile, the thickness of lamellar Si phase basically remained the same, and its length and width decreased gradually. The subsequent peritectic reaction became more intense and peritectic NiSi2 phase became narrower. The 123 K was the critical undercooling for the abrupt rise of eutectic growth velocity, the morphology transition of regular eutectic in the interdendritic gap of NiSi2 to the anomalous eutectic, and the sudden drop of the sample microhardness. The solute Ni content in NiSi2 and NiSi phases increased linearly with a rise in the undercooling, indicating the substantial expansion of solid solubility and the occurrence of an evident solute trapping phenomenon. For arc-melted samples with 8 mm diameter, the solidification microstructure mainly appeared as primary lamellar Si phase surrounded by peritectic NiSi2 phase plus eutectic (NiSi + NiSi2) phase, and the farther away from the sample bottom the smaller the undercooling and the higher the sample microhardness. As the sample diameter decreased to 2 mm, peritectic NiSi2 phase directly nucleated in the sample bottom and the microstructure composition in other regions resembled the large samples. The Si phase possessed lamellar and dendritic structures in the sample top and middle regions, respectively. Moreover, a maximum microhardness was determined in the lower middle region. The research has both scientific and industrial relevance, offering insights that could be applicable to the development and processing of complex alloy systems.

Tribological behavior of a Ti42Nb42Mo6Fe5Cr5 complex concentrated alloy and prediction through response surface methodology based mathematical modeling

In the present work, a novel Ti42Nb42Mo6Fe5Cr5 complex concentrated alloy (CCA) was developed using the vacuum arc melting technique. The as-cast CCA underwent a two-stage heat treatment process. In the first stage of heat treatment (HT 1), the alloy was heated to 900˚C. Subsequently, in the second stage of heat treatment (HT 2), the HT 1 samples were annealed at various temperatures, including 700˚C, 900˚C, and 1100˚C, for 20 h. The microstructure and mechanical response of the as-cast, HT 1 and HT 2 (annealed) samples were thoroughly investigated. The phase evolution, microstructure, and chemical composition were analyzed using XRD and SEM-EDS. The XRD analysis revealed major solid solution BCC phases (BCC 1 and BCC 2) with a small amount of Laves phase; however, the amount of Laves phase increased with increase in annealing temperature. The microhardness and elastic modulus of the CCA specimens were evaluated using instrumented micro-indentation. The CCA annealed at 1100˚C exhibits the highest microhardness and elastic modulus, with values of 5.94 ± 0.38 GPa and 124.40 ± 7.17 GPa, respectively. Response surface methodology (RSM) was used to develop a mathematical model aimed at predicting tribological characteristics, specifically the specific wear rate (SWR) and coefficient of friction (COF). RSM proposes a quadratic model to represent the mathematical relationship between input parameters for evaluating SWR and COF. The desirability function approach is employed to optimize input parameters to minimize both SWR and COF. The optimized values of SWR and COF are 6.87 × 10−4 mm3/N.m and 0.30 under a 27.52 N load, 2.86 Hz oscillation frequency, and 1100˚C annealing temperature. Surface topography analysis of the worn surface was evaluated using SEM and a profilometer to understand the wear mechanism and surface characteristics.

Synthesis, Physical, and Magnetocaloric Properties of MgZn2-Type Gd2Al3Rh.

Gd2Al3Rh was synthesized from the elements using arc-melting techniques, along with subsequent annealing. The title compound adopts the hexagonal MgZn2 type structure (space group P63/mmc, hP12, Wyckoff sequence hfa) with the Gd atoms found on the Mg positions (4f), the Rh (2a) and Al (6h) atoms occupying the two Zn sites of the prototype. In addition, mixing of Rh and Al on both crystallographic positions is observed. The magnetic susceptibility and magnetization experiments were conducted indicating ferromagnetic ordering below the Curie temperature of TC = 51.3(1) K and very high magnetization of 6.96(1) μB at 3 K and 70 kOe. In addition, heat capacity and electrical resistivity measurements were conducted. The magnetocaloric properties of ferromagnetic Gd2Al3Rh have been determined by means of magnetization measurements. For a field change of ΔH = 0 → 50 kOe the magnetic entropy change equals ΔSMmax = -4.8 J kg-1 K-1, leading to a relative cooling power of RCP = 283 J kg-1 for the same field change. The adiabatic temperature change was estimated to be ΔTadmax = 2.1 K using the heat capacity data.

Preparation, Deformation Behavior and Irradiation Damage of Refractory Metal Single Crystals for Nuclear Applications: A Review.

Refractory metal single crystals have been applied in key high-temperature structural components of advanced nuclear reactor power systems, due to their excellent high-temperature properties and outstanding compatibility with nuclear fuels. Although electron beam floating zone melting and plasma arc melting techniques can prepare large-size oriented refractory metals and their alloy single crystals, both have difficulty producing perfect defect-free single crystals because of the high-temperature gradient. The mechanical properties of refractory metal single crystals under different loads all exhibit strong temperature and crystal orientation dependence. Slip and twinning are the two basic deformation mechanisms of refractory metal single crystals, in which low temperatures or high strain rates are more likely to induce twinning. Recrystallization is always induced by the combined action of deformation and annealing, exhibiting a strong crystal orientation dependence. The irradiation hardening and neutron embrittlement appear after exposure to irradiation damage and degrade the material properties, attributed to vacancies, dislocation loops, precipitates, and other irradiation defects, hindering dislocation motion. This paper reviews the research progress of refractory metal single crystals from three aspects, preparation technology, deformation behavior, and irradiation damage, and highlights key directions for future research. Finally, future research directions are prospected to provide a reference for the design and development of refractory metal single crystals for nuclear applications.

Effect of Mn content in the Ti/Zr-based AB2 Laves type alloys on their electrochemical performance

In this work, we studied the impact of Manganese content on the structural and electrochemical properties of the AB2 Laves phase alloys. These multicomponent alloys were composed of 7 individual constituents with a composition Ti0.15Zr0.85La0.03V0.12Mn0.7+xFe0.12Ni1.2 and a variable Manganese content, x = 0.021, 0.035, 0.070. The alloys were prepared using arc melting and rapid solidification techniques. These alloys were characterized by X-ray diffraction and Scanning Electron Microscopy with X-ray Energy Dispersive Spectroscopy allowing to probe the phase-structural composition of the alloys, their microstructures, and elemental distribution among the phase constituents. The rapidly solidified alloys exhibited refined microstructures with a more uniform elemental distribution compared to their as-cast counterparts, the latter containing larger grain sizes and clustered La-rich phases. C15 and C14 Laves type structures contributed to the phase-structural composition of the alloys, with their proportions influenced by the Manganese content and the chosen preparation method. The study revealed a multi-feature relationship between the Manganese content, the phase abundances, and the electrochemical performances, with notable disparities between as-cast and rapidly solidified alloys. The alloy containing 3 wt% Manganese demonstrated the highest discharge capacity and superior activation performance for both preparation methods, suggesting the best choice when optimizing the composition of the anodes for achieving the best battery performance. The highest hydrogen diffusion rate was observed for the alloy containing 10 wt% Manganese which can be related to the catalytic role of Manganese in the processes of hydrogen exchange when present in these alloys.

Investigation on Microstructural and Mechanical Properties of FeNiMnCrCoTi0.1 High Entropy Alloy with B Addition

High-entropy alloys (HEAs) are alloys with high potential for use in defense, aircraft, and aerospace industries due to their properties such as high strength, hardness, wear resistance, corrosion resistance, and ability to operate at high temperatures. Therefore, in this study, FeNiMnCrCoTi0.1BX (x values in molar ratio, x = 0-1) high entropy alloys were produced by arc melting technique under protective gas atmosphere using a reverse vacuum method. The microstructural properties of the produced HEAs were examined by scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) analysis was also performed. The crystal lattice structure of the produced HEAs was determined by X-ray diffraction (XRD) analysis. Microhardness and compression tests were conducted to determine the mechanical properties of the produced HEAs. It is observed that the hardness of the FeNiMnCrCoTi0.1BX high-entropy alloy increases as the boron content increases. The highest microhardness obtained was 593.8 HV in the FeNiMnCrCoTi0.1B alloy. As the boron content increases, the yield stress has also increased in compression testing. The highest yield stress was determined to be 1329 MPa in the FeNiMnCrCoTi0.1B alloy.

Optimizing Al content to eliminate the brittle phase in lightweight TiZrNbTa0.1Alx refractory high-entropy alloys

Body-centered cubic (BCC) lightweight refractory high-entropy alloys (LWRHEAs) with Al contents have attracted much attention due to their low density and excellent mechanical properties. However, these typical lightweight alloys often suffer from poor room temperature plasticity. In this study, we prepared TiZrNbTa0.1Alx LWRHEAs by using a high-vacuum arc-melting technique and investigated the influence of Al content on the phase structures and mechanical properties. It was found that the TiZrNbTa0.1Al1 alloy showed a BCC solid solution matrix with some micrometer-sized Al3Zr5 precipitates and exhibited a density of 6.110 ± 0.003 g/cm3. The TiZrNbTa0.1Al1 alloy had a low mixed enthalpy of −20.831 kJ/mol, a compressive yield strength of 1037 ± 178 MPa, and a fracture plasticity of ∼6%. As a result of reducing the Al content, the TiZrNbTa0.1Al0.2 alloy showed a simple BCC phase structure without any precipitates and maintained a low density of 6.743 ± 0.008 g/cm3. The TiZrNbTa0.1Al0.2 alloy had a relatively high mixed enthalpy of −4.5577 kJ/mol, a high yield strength of 1022 ± 51 MPa, and a plasticity of >70%. The TEM analysis results demonstrated that the excellent mechanical properties of this LWRHEA were mainly attributed to the reducing Al content, which could elevate the mixed enthalpy of the alloy to eliminate the brittle Al3Zr5 phase and induce the formation of dense network dislocations at the grain boundaries.

Microstructural evolution and mechanical behavior of novel TiZrTaxNbMo refractory high-entropy alloys

The refractory high-entropy alloy (RHEA) with a body-centered-cubic (BCC) solid-solution structure has excellent high-temperature softening resistance, which has attracted wide interest in the field of high-temperature alloys. However, its limited room-temperature plasticity has greatly hindered its engineering application. To obtain an excellent strength-plasticity matching relationship, in this reported study, the Ta content in the high-entropy alloy (HEA) was adjusted to rectify this shortcoming. A series of TiZrTaxNbMo (x = 1.0, 0.9, 0.8, 0.7, and 0.6 at. percent, at%) RHEAs were prepared using the vacuum arc-melting technique, and the microstructure and mechanical properties of these RHEA alloys were systematically investigated. The experimental results show that the TiZrTaxNbMo RHEAs are composed of main BCC1 and minor BCC2 phases, which exhibit a dendritic structure. By reducing the Ta content, the elemental segregation caused by the non-equilibrium solidification is reduced. In terms of mechanical properties, with the decrease of Ta content, the hardness and room-temperature yield strength of the alloy decreases slightly, but the room-temperature plasticity increases significantly. The Ta0.7 alloy has the highest plasticity (34.8 %), which is about twice that of the equimolar Ta 1.0 alloy, while the yield strength remained at 1297 MPa. The excellent mechanical properties of the alloys can be attributed to solid-solution strengthening and the formation of moderate amounts of interdendritic regions. The interaction between slip bands and dislocations formed during compression of the Ta0.7 alloy decreased its work hardening. Moreover, the theoretical model of solid-solution strengthening elucidates that the calculated values of the alloy’s yield strength are consistent with that obtained experimentally.

Effects of Hf and C on microstructure and mechanical properties of Re0.1HfxTa1.6W0.4(TaC)y refractory medium-entropy alloy

The trade-off between high-temperature strength and room-temperature ductility represents a critical concern for practical application of refractory high-entropy alloys (RHEAs). Here, a set of five Re0.1HfxTa1.6W0.4(TaC)y refractory medium-entropy alloys (RMEAs) were fabricated using the vacuum arc melting technique, and the effect of Hf and C on the microstructures and mechanical properties of these alloys was investigated. These RMEAs exhibit excellent high-temperature strength and favorable plasticity at room-temperature. The microstructures of the Re0.1HfxTa1.6W0.4(TaC)y alloys are hypoeutectic or eutectic structures, consisting of BCC solid solution and primary and secondary carbides. The carbides can be classified into two types: M2C and MC. Hf and C have an important influence on the grain size, carbide type and spatial configuration of the alloy, and in turn, influence the mechanical properties of the alloy. For instance, the content of MC-type carbides is proportional to the addition of Hf element, whereby a higher proportion of Hf results in reduced plasticity at room-temperature and enhanced softening resistance at elevated temperatures in the alloy. The carbides and BCC matrix exhibit synergistic strengthening behavior. The ultimate compressive strength of the five Re0.1HfxTa1.6W0.4(TaC)y alloys at 1450 °C is >950 MPa, while maintaining a fracture strain exceeding 11% at room-temperature. Notably, the Re0.1Hf0.1Ta1.6W0.4(TaC)0.25 alloy demonstrates a compressive strength of 1110 MPa at 1450 °C, which is 2.3 times greater than that of the NbMoTaW alloy at 1400 °C. Additionally, the fracture strain of the Re0.1Hf0.1Ta1.6W0.4(TaC)0.25 alloy at room-temperature is 16.9%, which is 8 times higher than that of the NbMoTaW alloy. The Re0.1HfxTa1.6W0.4(TaC)y alloy exhibit excellent mechanical properties at both room and high temperatures, making it a potential candidate for applications in fields that require high strength at ultra-high temperatures.

High thermal stability effect of vanadium on the binary CuAl base alloy for a novel CuAlV high-temperature shape memory alloy

Abstract In this study, two high-temperature shape memory alloys (HTSMAs) of CuAlV with unprecedented chemical compositions were fabricated using the arc melting technique, followed by traditional ice-brine water quenching after the melting process. To characterize the shape memory properties and structure of the alloys, a series of tests including differential calorimetry (DSC and DTA), EDS, optical microscopy, and XRD were conducted. The DSC tests, performed at different heating and cooling rates, demonstrated highly stable reversible martensitic phase transformation peaks at high temperatures, which were also confirmed by the results of DTA tests. Microstructural XRD and optical microscopy tests were conducted at room temperature, revealing the martensitic structure of the alloys in both cases. Based on all the results, the effects of different minor amounts of vanadium additives directly on the CuAlV alloy were discussed.

Optimizing Thermoelectric Properties through Compositional Engineering in Ag-Deficient AgSbTe2 Synthesized by Arc Melting.

Thermoelectric materials offer a promising avenue for energy management, directly converting heat into electrical energy. Among them, AgSbTe2 has gained significant attention and continues to be a subject of research at further improving its thermoelectric performance and expanding its practical applications. This study focuses on Ag-deficient Ag0.7Sb1.12Te2 and Ag0.7Sb1.12Te1.95Se0.05 materials, examining the impact of compositional engineering within the AgSbTe2 thermoelectric system. These materials have been rapidly synthesized using an arc-melting technique, resulting in the production of dense nanostructured pellets. Detailed analysis through scanning electron microscopy (SEM) reveals the presence of a layered nanostructure, which significantly influences the thermoelectric properties of these materials. Synchrotron X-ray diffraction reveals significant changes in the lattice parameters and atomic displacement parameters (ADPs) that suggest a weakening of bond order in the structure. The thermoelectric characterization highlights the enhanced power factor of Ag-deficient materials that, combined with the low glass-like thermal conductivity, results in a significant improvement in the figure of merit, achieving zT values of 1.25 in Ag0.7Sb1.12Te2 and 1.01 in Ag0.7Sb1.12Te1.95Se0.05 at 750 K.

Microstructure and Friction Properties of AlCrTiVNbx High-Entropy Alloys via Annealing Manufactured by Vacuum Arc Melting.

To enhance the friction and wear properties of alloys, AlCrTiVNbx high-entropy alloys (HEAs) with various Nb contents were prepared using the arc melting technique and then annealed at 1000 °C for 2 h. The microstructure and hardness changes in the AlCrTiVNbx (x = 0.3, 0.4, and 0.5) HEAs after casting and annealing were studied via scanning electron microscopy, X-ray diffractometry, optical microscopy and the Vickers hardness test. The MFT-EC400 ball disc reciprocating friction and wear tester was used to investigate the wear resistance of the HEAs before and after annealing. The results show that the annealed AlCrTiVNbx HEAs changed from a single-phase structure to a multi-phase structure, and the content of the face-center cubic (FCC) phase and hexagonal close-packed (HCP) phase further increases with the increase in Nb content. The hardness value of the annealed HEAs is greatly enhanced compared with the casting state, and the hardness of the Nb0.5 HEA is increased from 543 HV to 725 HV after annealing. The wear resistance of the alloys after the annealing treatment is also greatly improved, among which Nb0.5 has the best wear resistance. The average friction coefficient of Nb0.5 is 0.154 and the wear rate is 2.117 × 10-5 mm3/(N·m). We believe that the precipitation strengthening after the annealing treatment and the lubrication effect of the FCC phase are the reasons for the significant improvement in wear resistance. The morphology of the samples indicates that the wear mechanism of the alloy includes adhesive wear, abrasive wear and a certain degree of oxidation wear.

Smart alloy metalized novel photonic NEMS photodiode with CuAlV/n-Si/Al junction structure

In this work, a novel smart (shape memory) alloy metalized photonic silicon wafer photodiode with Schottky type CuAlV/n-Si/Al contact structure as a nano-electro-mechanical-system (NEMS) photodevice was fabricated by thermal evaporation technique. The CuAlV memory alloy used as the top Schottky metal contact electrode was produced by arc melting technique and a subsequent quenching in an iced-brine water medium, and its shape memory effect characteristics were revealed by thermal and structural tests. The fabricated photonic NEMS photodiode was characterized by different photo-electrical (I-V, I-t) and frequency/time dependent and illuminated capacitance (C–V/f, C-t, C–V/ill.) and conductance-voltage (G-V) measurements under different frequencies and artificial light intensity power conditions. The I-V tests showed an excellent current rectifying ability and very well net photocurrent generation features of the photodiode. The specific detectivity of the photodiode was found as high as almost approaching 1011 Jones. The SCLC (space charge limited current conduction) analyses made on the double-log I-V plots of the photodiode revealed that the trap-filling TFL-SCLC and trap-free SCLC current conduction mechanisms are the two prevailing conduction mechanisms in the forward bias voltage region. The density of interface states (Dit) of the fabricated photodiode was determined. Moreover, an excellent reproducibility of light-induced photocapacitance formation of the novel photodiode was demonstrated by C–V/t measurements under different artificial light power intensities.

Microstructure and corrosion properties of Cr41CoFeNi eutectic high-entropy alloy in sulfuric acid solution

A new eutectic high-entropy alloy (EHEA) of Cr41CoFeNi was prepared by arc melting technique. The microstructure and corrosion resistance of the Cr41CoFeNi EHEA were systematically investigated by EBSD, TEM, EIS and XPS analyses. The results revealed that the Cr41CoFeNi EHEA showed a dual-phase structure consisting of BCC phase and FCC phase, and the morphologies displayed the lamellar eutectic and network-shaped eutectic. Compared with 316 L stainless steel, the Cr41CoFeNi EHEA exhibited a better anti-corrosion property in 0.5 M H2SO4 solution. This was mainly attributed to the formation of a dense and stable Cr-oxide layer on the surface of Cr41CoFeNi EHEA, which retarded further dissolution of the matrix. Moreover, bound water could adsorb metal ions to form a new protective film, which played an important role in improving the corrosion resistance of the Cr41CoFeNi EHEA. However, the elemental segregation and chemical potential difference between phases increased the defects in the passive film and accelerated its pitting corrosion of low potential phase. Moreover, the (Co, Fe, and Ni)-enriched FCC structured phase was preferentially eroded.

Mechanical and Tribological Performance of AlCrFeCuNi-(Vx) HEAs Synthesized via Arc Melting technique

The AlCrFeCuNi-(Vx) High Entropy Alloy (HEA) was created via arc-melting and casting processes. The influence of vanadium (V) on the Nano mechanical behaviour, microstructural development, as well as the wear performance of the produced HEAs was examined. Notable improvements to the Nano hardness of the HEAs were evident with an increase in V content from 1at% to 5at%. The addition of V altered the frictional behaviour of the HEA with an increased coefficient of friction as V is increased. The addition of V also greatly affected the microstructural orientation of the HEA, exhibiting signs of homogenization as V content increased.