Low Dislocation Density Research Articles

GaAs Solar Cells Grown Directly on V-Groove Si Substrates.

The direct epitaxial growth of high-quality III-V semiconductors on Si is a challenging materials science problem with a number of applications in optoelectronic devices, such as solar cells and on-chip lasers. We report the reduction of dislocation density in GaAs solar cells grown directly on nanopatterned V-groove Si substrates by metal-organic vapor-phase epitaxy. Starting from a template of GaP on V-groove Si, we achieved a low threading dislocation density (TDD) of 3 × 106 cm-2 in the GaAs by performing thermal cycle annealing of the GaAs followed by growth of InGaAs dislocation filter layers. This approach eliminates the need for a metamorphic buffer to directly integrate low-TDD GaAs on Si. We used these low-TDD GaAs/V-groove Si templates to grow GaAs double heterostructures that had a minority carrier lifetime of 5.7 ns, as measured by time-resolved photoluminescence, a value consistent with the material quality associated with a 20%+ efficient GaAs solar cell. However, front-junction GaAs solar cells grown on these low-TDD substrates produced a conversion efficiency of only 6.6% without an antireflection coating. Electron channeling contrast imaging measurements on this cell showed a high density of misfit dislocations at the interface between the AlInP/GaInP window layer and the GaAs absorber and between the GaAs absorber and the GaInP back surface field (BSF), likely causing a high surface recombination velocity and thus poor performance. We showed that we could reduce (and in the case of the BSF, eliminate) these dislocations by employing an AlGaAs-based window layer and BSF. Compared to GaInP, AlGaAs has dislocation glide properties that are more similar to those of GaAs, resulting in more even threading dislocation glide between layers. AlGaAs passivation improved the external quantum efficiency and open-circuit voltage of the devices, but the overall device performance was still low at an efficiency of 7.7% without an antireflection coating, likely due to cracking in the devices. This work demonstrates a route to high material quality in GaAs grown directly on Si that can be used for the production of III-V/Si optoelectronic devices.

Influence of asymmetric rolling paths on the microstructure, texture, mechanical behavior, and electrical conductivity of electrolytic tough-pitch copper

In this work, the influence of asymmetric rolling paths on the microstructure, texture, mechanical behavior, and electrical conductivity of electrolytic tough-pitch copper was studied. Four different asymmetric rolling paths including unidirectional (UD), rolling (RD), transverse (TD), and normal (ND) with a thickness reduction of 90% were applied. Based on simulation results, the uniformity of strain distribution in the UD path was less than the other paths, the RD and ND paths had a better distribution of strain along the thickness, and the TD path exhibited the best strain distribution. Because of this, the TD, ND, and RD samples revealed a better distribution of copper oxide particles compared to the UD sample. The homogeneity of texture through the sheet thickness for the RD, TD, and ND paths was more than that for the UD path due to the uniform strain distribution. Unlike the other samples, the UD sample exhibited {001}〈110〉 Rotated Cube and {001}〈100〉 Cube orientations in the areas close to the surface due to the formation of severe accumulated strain. The maximum yield strength (405.5 MPa) and tensile strength (419.0 MPa) belonged to the RD sample. The TD sample showed a lower strain hardening rate as a result of easier cross-slip. The highest electrical conductivity (85.2 %IACS) belonged to the TD sample due to its lower dislocation density. The presence of θ-fiber and γ-fiber improved the electron conductivity of copper.

Orientation-dependent strain and dislocation in HVPE-grown α -Ga2O3 epilayers on sapphire substrates

Orientation-dependent substrates provide effective platforms for achieving α-Ga2O3 with low dislocation densities, whereas the associated strain and dislocation dynamics have not been fully explored. Herein, we investigated the evolution of growth mode, interfacial strain, and dislocation propagation in the α-Ga2O3 epitaxial layer with various orientations, grown by the halide vapor-phase epitaxy. Strain tensor theory and geometric phase analysis indicate that the m-plane α-Ga2O3 epitaxial layer exhibits the lowest misfit tensile strain, measured at εxx = 1.46% and εyy = 1.81%, resulting in the lowest edge dislocation density. The m-plane lattice exhibits an inclination of 33.60°, while the c-plane lattice is horizontally aligned and the a-plane lattice oriented perpendicularly. The orientation-dependent growth significantly influences stress relaxation through the generation of misfit dislocations, originating from either basal or prismatic slip. Edge dislocations, induced by misfit dislocations, favor the c-axis, remaining well confined within the in-plane interfacial layer of the m-plane α-Ga2O3, leading to reduced low edge dislocation density in the subsequent thick epitaxial layer. These findings shed light on the epitaxial dynamics of α-Ga2O3 heteroepitaxy, paving the way for the development of high-performance power devices.

Deformation characteristics of Ti-Ni-Fe based multiphase intermetallic: Experiments and atomistic simulation

This study deals with the development of Ti-Ni-Fe based multi-phase intermetallic having high strength with enhanced ductility and elucidation of their deformation characteristics. The intermetallic exhibited a compressive strain and strength of ⁓ 11 % and ⁓ 2.1± 0.112 GPa at room temperature (RT), respectively. MD simulation at RT showed a higher dislocation density in the DO24 phase, where most of the dislocations were found to be superpartials 13101̅0 and 1311̅00 separated by super intrinsic stacking faults (SISF), which was further corroborated with TEM analysis. It was found that despite its low volume fraction, DO24 phase governed the plastic deformation. Further, hot compression of Ti45Ni50Fe5 exhibited yield strength anomaly (YSA), where yield strength decreased from room temperature to 373 K followed by an increase at 473 K and 573 K. MD simulation of hot compression showed lower dislocation density (⁓300–551×10−6Å−2) for B2 matrix at all temperatures, indicating strength is predominantly governed by it. The dislocation density of B2 matrix was found to increase with temperature up to 373 K followed by a decrease at 473 K and 573 K. This difference in dislocation density has been attributed to the cross-slip of 121̅11 screw partials from {110} plane to {211} plane, resulting in the formation of dislocation lock that led to YSA behavior.

Comparative study on contribution of bimodal microstructure and heterogeneous microstructure to mechanical properties of ZK60 alloy

In this work, we compared the effects of bimodal microstructure and heterogeneous microstructure on the mechanical properties and strengthening mechanisms of ZK60 alloy. The bimodal microstructure is composed of coarse un-dynamically recrystallized (un-DRXed) grains with strong basal texture and fine dynamically recrystallized (DRXed) grains with weak texture, while the heterogeneous microstructure is composed of coarse DRXed grains and fine DRXed grains. The result suggests that high-density dislocations and high-density precipitates have significant contribution to the strength. The high-density dislocations in un-DRXed grains cause the formation of an uneven distribution of precipitates in the ZK60 alloy which results in the high yield strength of 305 MPa, ultimate tensile strength of 344 MPa and elongation of 12% in the bimodal-structured ZK60 alloy. In comparison, the heterogeneous-structured ZK60 alloy lacks the strengthening effect from high-density dislocations and precipitates, and a lower YS of 226 MPa, and UTS of 305 MPa are achieved. The result also indicates the weak texture, low density of dislocations, low density of precipitates, and stronger ability of storing dislocations in coarse grains for heterogeneous microstructure are helpful to the ductility. Thus, HE sample exhibits higher elongation of 23% than BI sample. The finding shed light on the microstructure designing of high-performance Mg alloys.

The thermal deformation behavior and processing map of TC9 titanium alloy

This investigation delves into the thermal deformation behavior of TC9 titanium alloy. Compression tests at isothermal conditions were performed on a Gleeble thermal simulator under conditions spanning 700–1200 °C and strain rates of 0.001–1 s−1. The true stress-true strain curves indicated that stress increases with rising strain rate and decreasing temperatures. The softening mechanisms in the biphasic and monophasic regions were discussed. By correcting errors caused by friction, the strain-compensated Arrhenius-type constitutive equation, which accurately describes the flow behavior of TC9 titanium alloy, has been established. A processing map at a strain of 0.7 was constructed based on the power dissipation factor, revealing an unstable region at 700–800 °C/0.01–1 s−1 and 800–900 °C/0.1–1 s−1, where microcrack defects were observed, suggesting that processing should be avoided in this region. Efficiency values as high as 60–70 % indicate superplasticity deformation, with corresponding m values within this efficiency range of approximately 0.4–0.5, reaching the strain rate sensitivity index range of superplasticity titanium alloys. Tensile tests conducted at 900 °C and a deformation rate of 0.001 s−1 showed elongation exceeding 100 %. The sample compressed at 900 °C and 0.001 s−1 exhibits small grain size, uniform orientation, the lowest dislocation density, and a uniform two-phase mixture. These microstructural features indicate the material's good machinability.

Tailoring Strength and Ductility in Dual-Phase High-Entropy Alloys: Insights from Deep Learning Molecular Dynamics Simulation on FCC/BCC Thickness Ratios

This study investigates the influence of FCC/BCC thickness ratios on the mechanical properties of AlCoCrFeNi dual-phase high-entropy alloys (DP-HEAs) using deep learning-enhanced molecular dynamics simulations. The results demonstrate that varying the thickness ratio significantly affects the stress-strain behavior, dislocation density evolution, and local structural transformations during tensile deformation. DP_0.5, with a thinner BCC phase, exhibits higher dislocation densities and enhanced strain hardening, resulting in increased strength but reduced ductility. In contrast, DP_3.0, with a thicker BCC phase, shows lower dislocation densities, leading to improved ductility but lower strength. The phase transformation from BCC to HCP structures is a key mechanism contributing to plastic deformation, with the BCC/FCC interface playing a critical role in dislocation nucleation and propagation. These findings provide valuable insights into optimizing the microstructural design of DP-HEAs to achieve a tailored balance of strength and ductility, offering the potential for advanced structural applications.

Optimization in strength-ductility synergy of extruded Mg-3Sn-2Al-1Zn-0.6Y-0.6Nd alloy via novel FPE processes

Three novel FPE processes were proposed by integrating the advantages of conventional extrusion and ECAE, optimizing the strength-ductility synergy of extruded Mg-3Sn-2Al-1Zn-0.6Y-0.6Nd alloy. The deformation mechanism, evolution of texture and variation of the tensile properties of the alloy were investigated. Findings indicate that the alloys fabricated by the FPE processes exhibit a finer and more uniform microstructure with the lowest dislocation density, undergoing the most complete DRX. The FPE process breaks the strength-ductility tradeoff dilemma of the magnesium alloys, achieving a synergistic enhancement of both strength and ductility. The FPE-105 process was determined to be the best process for strengthening the alloy, with a 24.4 % (340 MPa) increase in UTS compared to the FE-10 sample, along with an impressive doubling of the ductility (18.6 %). The excellent mechanical properties provided by the FPE-105 process are primarily stem from the uniform and fine grain distribution and texture modification. The successful application of the three FPE processes to the fabrication of extruded magnesium alloys demonstrates that the series of novel extrusion processes can be further optimized to create magnesium alloys with excellent strength-ductility.

Dislocation‐induced local symmetry reduction in single‐crystal KNbO3 observed by Raman spectroscopy

AbstractIn recent years, dislocation‐tuned functionalized ceramics have become one of the focal points of modern materials research due to their outstanding properties. These range from improved electrical conductivity and ferroelectric properties to dislocation‐enhanced toughening and superconductivity, caused by local strain fields. The aim of this work is to investigate the dislocation‐induced structural changes in single‐crystal KNbO3 by micro‐Raman spectroscopy. Dislocation‐rich regions with tailored densities have been generated using the Brinell indenter scratching method. The influence of the dislocations on the single‐crystal structure can be observed in the Raman spectra. The activation of additional Raman modes is observed, which does not occur in regions of low dislocation density. This observation is confirmed by DFT calculations of vibrational modes and is attributed to a reduction in the crystal symmetry due to increased defect densities in plastically deformed KNbO3. In addition, an increase in compressive stress at higher dislocation densities can be demonstrated by a blueshift in Raman mode positions.

The regulation of dislocation and precipitated phase improving hydrogen embrittlement resistance of pipeline steel in high pressure hydrogen environment

In this study, the hydrogen embrittlement behavior of quenched pipeline steel tempered at 550 °C to 650 °C in a high-pressure hydrogen environment was analyzed. Hydrogen permeation tests and microstructural analyses indicated that the dislocation density of the steel decreases with increasing tempering temperature, while precipitates gradually nucleate and grow. These hydrogen traps interact with hydrogen atoms, resulting in significantly higher diffusible hydrogen content in steel tempered at 550 °C compared to that tempered at 600 °C and 650 °C. Fatigue crack growth (FCG) test results show that steel tempered at 600 °C and 650 °C exhibits significantly better hydrogen embrittlement resistance than steel tempered at 550 °C. This is primarily due to the combined effect of the high hydrogen concentration, high dislocation density and low nano carbide content in the steel tempered at 550 °C, which inhibits dislocation slip and emission, leading to high crack tip stress and rapid crack propagation. In contrast, the low dislocation density and and dispersed nano carbides in steel tempered at 600 °C and 650 °C facilitate some dislocation slip and emission, result in crack tip stress relaxation and reduced crack propagation rate. Properly controlling the initial dislocation density and increasing the density of irreversible hydrogen traps can enhance the strength of materials while improving their resistance to hydrogen embrittlement.

Reducing dislocations for room-temperature continuous-wave InGaAs/AlGaAs multiple quantum well lasers monolithically grown on Si

As dislocation-sensitive light-emitting devices, quantum well lasers monolithically grown on Si substrates operate poorly compared to their counterparts on native ones. In this work, a GaAs/Si virtual substrate with a low threading dislocation density of 8.9 × 106/cm2 was achieved by using a combined dislocation-reducing method. Meanwhile, by using two In-containing strained layer separately inserted into upper and lower AlGaAs cladding layers, the active region was virtually free of gliding dislocations. With the reduced dislocations in the active region, the fabricated Si-based broad-stripe ridged lasers exhibited continuous-wave lasing at room temperature, and a low threshold current density of 1015 A/cm2, high operation temperature of 90 °C as well as a device lifetime of over 87.25 h were achieved. These results demonstrate an experimentally feasible way to optimize a Si-based InGaAs/AlGaAs quantum well laser and further promote the research on monolithic integration.

Large-Size and Ultrahigh Purity Tungsten with Enhanced Physical Properties via Chemical Vapor Deposition.

Conventional powder metallurgy techniques fail to meet the demands for ultrahigh purity tungsten (UHPW) and scalable component sizes required by the semiconductor industry. In this study, ultrahigh purity (99.999998 wt %) large-size tungsten parts, with an adjustable thickness and a diameter of 350 mm, were prepared via a chemical vapor deposition (CVD) method using ultrahigh purity (99.9999 wt %) tungsten hexafluoride (WF6) as the precursor. The microstructure and physical properties of the resulting CVD-UHPW were evaluated and compared with those of powder metallurgy tungsten (PM-W). The results indicate that CVD-UHPW displays a columnar grain microstructure with a lower dislocation density and internal strain, whereas PM-W shows an equiaxed grain microstructure. CVD-UHPW has a density of 19.17 g/cm3, closely matching the theoretical density of tungsten (19.35 g/cm3) and significantly higher than PM-W's density of 18.79 g/cm3. The specific heat capacities of CVD-UHPW, measured from 298 to 1473 K, range from 0.113 to 0.146 J/g·K, similar to PM-W's range of 0.120 to 0.151 J/g·K. CVD-UHPW shows improved electrical and thermal conductivities compared to PM-W, with values ranging from 1.68 × 106 to 1.78 × 107 S/m and 105.7 to 196.4 W/(m·K) from 298 to 1473 K. This study highlights the potential of the CVD method for the large-scale production of ultrahigh purity tungsten parts, emphasizing its significant applicability across various industries.

Ultra-high brightness Micro-LEDs with wafer-scale uniform GaN-on-silicon epilayers

Owing to high pixel density and brightness, gallium nitride (GaN) based micro-light-emitting diodes (Micro-LEDs) are considered revolutionary display technology and have important application prospects in the fields of micro-display and virtual display. However, Micro-LEDs with pixel sizes smaller than 10 μm still encounter technical challenges such as sidewall damage and limited light extraction efficiency, resulting in reduced luminous efficiency and severe brightness non-uniformity. Here, we reported high-brightness green Micro-displays with a 5 μm pixel utilizing high-quality GaN-on-Si epilayers. Four-inch wafer-scale uniform green GaN epilayer is first grown on silicon substrate, which possesses a low dislocation density of 5.25 × 108 cm−2, small wafer bowing of 16.7 μm, and high wavelength uniformity (standard deviation STDEV < 1 nm), scalable to 6-inch sizes. Based on the high-quality GaN epilayers, green Micro-LEDs with 5 μm pixel sizes are designed with vertical non-alignment bonding technology. An atomic sidewall passivation method combined with wet treatment successfully addressed the Micro-LED sidewall damages and steadily produced nano-scale surface textures on the pixel top, which unlocked the internal quantum efficiency of the high-quality green GaN-on-Si epi-wafer. Ultra-high brightness exceeding 107 cd/m2 (nits) is thus achieved in the green Micro-LEDs, marking the highest reported results. Furthermore, integration of Micro-LEDs with Si-based CMOS circuits enables the realization of green Micro-LED displays with resolution up to 1080 × 780, realizing high-definition playback of movies and images. This work lays the foundation for the mass production of high-brightness Micro-LED displays on large-size GaN-on-Si epi-wafers.

Damage-tolerant oxides by imprint of an ultra-high dislocation density

Dislocations in ductile ceramics offer the potential for robust mechanical performance while unlocking versatile functional properties. Previous studies have been limited by small volumes with dislocations and/or low dislocation densities in ceramics. Here, we use Brinell ball scratching to create crack-free, large plastic zones, offering a simple and effective method for dislocation engineering at room temperature. Using MgO, we tailor high dislocation densities up to ∼1015 m−2. We characterise the plastic zones by chemical etching, electron channelling contrast imaging, and scanning transmission electron microscopy, and further demonstrate that crack initiation and propagation in the plastic zones with high-density dislocations can be completely suppressed. The residual stresses in the plastic zones were analysed using high-resolution electron backscatter diffraction. With the residual stress being subsequently relieved via thermal annealing while retaining the high-density dislocations, we observe the cracks are no longer completely suppressed, but the pure toughening effect of the dislocations remains evident.

InP-based strain engineered InAs(Sb)/InAsPSb multiple quantum wells with tunable emission and high internal quantum efficiency enabled by Sb incorporation

A type I InAs(Sb)/InAsPSb strain engineered multiple quantum wells light emitting diodes system has been demonstrated. Tensile InAsPSb quantum barriers with a high degree of band offset (∆EC = 116–123 meV, ∆EV = 193–250 meV) were used to compensate for the high compressive strain of the InAs(Sb) quantum wells. The structure was grown on the n+-InAsxP1−x metamorphic buffer with a high degree of relaxation (98%), low surface roughness (0.69 nm), and low dislocation density. Through careful strain engineering design, the compressive strain of InAs(Sb) reaches 0.57%–1.52% without strain relaxation. The incorporation of Sb into the multiple quantum wells not only reduces the bandgap but also improves the interface quality by acting as an effective surfactant. Structural analysis reveals superior quality in InAsSb/InAsPSb multiple quantum wells compared to InAs/InAsPSb multiple quantum wells, demonstrating significantly reduced interface roughness and suppression of the Stranski–Krastanov growth mode. Room temperature electroluminescence measurements show a tunable emission wavelength ranging from 2.7 to 3.3 μm, accompanied by a narrow full width at half maximum value of 45 meV. Photoluminescence analysis indicates that the internal quantum efficiency of InAsSb/InAsPSb multiple quantum wells is 5.5%, which is 7 times higher than that of InAs/InAsPSb.

A molecular dynamics study on mechanical performance and deformation mechanisms in nanotwinned NiCo-based alloys with nano-precipitates under high temperatures

Abstract Molecular dynamics simulations are performed to investigate the mechanical behavior of nanotwinned NiCo-based alloys containing coherent L12 nano-precipitates at different temperatures, as well as the interactions between the dislocations and nano-precipitates within the nanotwins. The simulation results demonstrate that both the yield stress and flow stress in the nanotwinned NiCo-based alloys with nano-precipitates decrease as the temperature rises, because the higher temperatures lead to the generation of more defects during yielding and lower dislocation density during plastic deformation. Moreover, the coherent L12 phase exhibits excellent thermal stability, which enables the hinderance of dislocation motion at elevated temperatures via the wrapping and cutting mechanisms of dislocations. The synergistic effect of nanotwins and nano-precipitates results in more significant strengthening behavior in the nanotwinned NiCo-based alloys under high temperatures. In addition, the high-temperature mechanical behavior of nanotwinned NiCo-based alloys with nano-precipitates is sensitive to the size and volume fraction of the microstructures. These findings could be helpful for the design of nanotwins and nano-precipitates to improve the high-temperature mechanical properties of NiCo-based alloys.

Phase transformation process and toughening mechanism of 12Cr1MoV heat-resistant steel for high-pressure boilers by external shower and internal spray heat treatment

To optimize the heat treatment process for 12Cr1MoV heat-resistant steel, this study designed a novel process of external shower and internal spray (ESIS), followed by air cooling. This new approach was simulated in the laboratory. The study focused on the variation in impact energy and the microstructural changes in the experimental steel subjected to different processes, specifically the T890 and T740 processes (where the numbers represent the termination temperature of ESIS). The phase transformation processes and toughening mechanisms of the steel after these treatments were thoroughly investigated. The theoretical analysis revealed that the microstructures of T890 and T740 steels consist of quasi-polygonal ferrite (QPF), granular bainite (GB), and pearlite. The QPF in T890 steel forms at a higher temperature compared to T740 steel, leading to a lower dislocation density and carbon content in QPF during the subsequent cooling phase. This results in the QPF in T890 steel having a hardness of 1.02 GPa lower than that of the QPF in T740 steel. The higher hardness of QPF in T740 steel correlates with reduced toughness and resistance to crack propagation. Under impact loading, the QPF in T740 steel exhibits insufficient crack propagation resistance to counteract the effects of microscopic defects within the tensile stress region of the fracture. Consequently, cracks preferentially propagate within the QPF, creating a relatively flat propagation path. In comparison, the fracture of T740 steel demonstrates a straighter propagation path in the tensile stress region than T890 steel, resulting in significantly lower impact energy for T740 steel.

Mechanical characterization of nanocrystalline Cu-Ag alloys subjected to shear deformation

ABSTRACT This study investigates the mechanical behaviour of nanocrystalline Cu-Ag alloys using molecular dynamics simulations combined with detailed analyses of dislocation densities, atomic populations, and deformation characteristics. Shear tests were conducted across three different atomic compositions at temperatures ranging from 10 K to 500 K. The influence of temperature and Ag impurities on the mechanical properties of nanocrystalline Cu is explored. Elevated temperatures are found to promote plastic deformation by increasing atomic mobility, resulting in reduced dislocation densities and flow stresses. Increasing Ag content correlates with lower dislocation densities, highlighting enhanced plastic activity between grain and grain boundaries. Structural population analysis underscores the significant impact of Ag species on the mechanical response of nanocrystalline Cu. Further investigations are warranted to explore additional deformation mechanisms. These findings contribute to a deeper understanding of nanocrystalline Cu-Ag alloys, informing the design of novel materials with tailored mechanical properties.

Making large-size fail-safe steel by deformation-assisted tempering process

Synergistically improving the strength and toughness of metallic materials is a central focus in the field of physical metallurgy. Yet, there is a noticeable lack of research in strengthening and toughening large-size metal components, whereas those components are extensively used in the modern industry. In this work, a deformation-assisted tempering (DAT) process was proposed to create a novel microstructure in 1.4 tons low-alloyed plain steel. After DAT treatment, the steel contains low dislocation density but high density of low-angle subgrain boundaries and dispersed spherical nano carbides. Such microstructure enables a much better combination of tensile strength and fracture toughness compared to the small-size quench and temper steels. The significant improvement in low-temperature impact toughness is due to the occurrence of delamination and subsequent large plastic deformation at the notch tip. The DAT process can provides a new strategy for the development of large-size fail-safe steel with excellent strength and fracture resistance.

Enhanced hot corrosion resistance of AlCoCrFeNi2.1 high entropy alloy coatings by extreme high-speed laser cladding

Extreme high-speed laser cladding (EHLC) and multiple laser remelting (EHLC-MR) are used to improve hot corrosion resistance of AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA) coatings by refining their microstructures, introducing low angle grain boundaries (LAGBs) and high densities of dislocations as well as higher compressive residual stresses (CRSs) in the coatings. The experimental results show that finer microstructure, more LAGBs and high densities of dislocations are beneficial to increase Al2O3 nucleation sites and promote the uniform formation of the oxide layer on the coating surface. On the other hand, higher CRSs suppress the initiation and propagation of cracks as well as enhance the adhesion between the oxide layer and the substrate. Thus the hot corrosion resistance of the EHEA coatings under a molten salt of 75 % Na2SO4 + 25 % NaCl at 900°C is improved significantly. These novel results provide effective approach for designing elevated-temperature materials.