High-temperature Annealing Research Articles

Encapsulation of Er-doped GeO2 nanofilms by Al2O3 atomic layers: Surficial sensitivity to trimethylaluminum and improvement on electroluminescence

Based on previous results of the Er-doped GeO2 nanofilms fabricated by atomic layer deposition (ALD), the interfacial reactions of Al2O3 precursor within the GeO2/Al2O3:Er nanolaminates are investigated. The ALD pulse of Al(CH3)3 etches the as-deposited GeO2 nanofilm, while the oxidation of Al(CH3)3 by ozone realizes the deposition of atomic Al2O3 layer onto GeO2 surface. The Al2O3 atomic layers with ≥4 ALD cycles improve the thermal stability of the ALD GeO2 nanofilms, which restrain the formation of nanograins and also the reduction of film thickness during high-temperature annealing, giving rise to smooth GeO2/Al2O3:Er nanolaminates. For the 1530 nm electroluminescence (EL) from the silicon-based devices fabricated using the GeO2/Al2O3:Er nanolaminates annealed at 800 °C, the excitation efficiency is tripled to 22.1 %. The conduction of the energetic electrons resulting in the EL emissions still confirms to the trap-assisted tunneling mechanism within these amorphous GeO2/Al2O3:Er nanolaminates. The prototype devices based on the Al2O3-inserted nanolaminates exhibit comparatively increased operation time. These GeO2/Al2O3:Er nanolaminates with enhanced stability and improved optoelectronics performance pave the way for the practical utilization of ALD GeO2 nanofilms.

Efficient organic solar cells enabled by sustainable and synergetic device engineering

In order to accelerate the transfer of organic solar cells (OSCs) from lab to fab, this work develops a synergetic strategy by integrating low-cost material, green solvent, bio-based additive and low-temperature post-treatment to sustainably fabricate OSCs. The donor polymer PTQ10 composing of simple building blocks, accompanied by the acceptor L8-BO, is dissolved in the green solvent tetrahydrofuran, wherein a bio-based cinnamonitrile is firstly used as solvent additive. Moreover, fluorous solvent soaking (FSS) is employed as post-treatment to replace the high-temperature and time-consuming thermal annealing. Systematic investigations are performed to unravel the mechanism of the device engineering developed in this work. Differing from the one-way movement of additive, the fluorous solvent can penetrate into and come out the film in cycles. Meanwhile, some L8-BO is selectively dissolved and brought out by the fluorous solvent, so this partial L8-BO bears the function as solid additive to optimize the morphology. As a result, the device achieves a remarkable power conversion efficiency of 17.11%, among the best efficiencies of OSCs prepared by non-halogenated non-aromatic solvents. In addition, the excellent universality ensures this strategy is also effective in the thick-film OSCs.

High temperature decomposition and age hardening of single-phase wurtzite Ti1−xAlxN thin films grown by cathodic arc deposition

Wurtzite TmAlN (Tm=transition metal) themselves are of interest as semiconductors with tunable band gap, insulating motifs to superconductors, and piezoelectric crystals. Characterization of wurtzite TmAlN is challenging because of the difficulty to synthesize them as single-phase solid solution and such thermodynamic, elastic properties, and high temperature behavior of wurtzite Ti1−xAlxN is unknown. Here, we investigated the high temperature decomposition behavior of wurtzite Ti1−xAlxN films using experimental methods combined with first-principles calculations. We have developed a method to grow single-phase metastable wurtzite Ti1−xAlxN (x=0.65, 0.75, 085, and 0.95) solid-solution films by cathodic arc deposition using low duty-cycle pulsed substrate-bias voltage. We report the full elasticity tensor for wurtzite Ti1−xAlxN as a function of Al content and predict a phase diagram including a miscibility gap and spinodals for both cubic and wurtzite Ti1−xAlxN. Complementary high-resolution scanning transmission electron microscopy and chemical mapping demonstrate decomposition of the films after high temperature annealing (950∘C), which resulted in nanoscale chemical compositional modulations containing Ti-rich and Al-rich regions with coherent or semicoherent interfaces. This spinodal decomposition of the wurtzite film causes age hardening of 1–2 GPa. Published by the American Physical Society 2024

Assessing the key parameters for efficient sensitized infrared emission from erbium-doped SnO2 films

Erbium-doped SnO2 films (Er:SnO2) combine the properties of Er3+ and SnO2, providing an avenue for developing unique luminophores with sensitized infrared emission. In such a system, Er3+ luminescence evolves over doping-concentration and thermal-treatment shifts, where low-temperature-annealed or highly-doped Er:SnO2 exhibits degraded emission. To fully exploit the potential of Er:SnO2, a deep understanding of the underlying physical process is required. This paper discusses the parameters determining the intensity of sensitized Er3+ emission and their evolution with doping concentration and thermal treatment. The observation of temperature-independent decay of Er3+ luminescence excludes the nonradiative interaction of the Er3+4I13/2 → 4I15/2 transition with defects in SnO2. Moreover, despite the loss of Er3+ optical activity observed in highly-doped or low-temperature-annealed samples, the sensitized emission intensity doesn't scale linearly with it. Instead, the most prominent parameter determining the sensitized emission intensity is found to be the energy transfer efficiency from SnO2 to Er3+, which highly depends on the crystallinity of SnO2. The presence of defects in low-crystallinity SnO2, that is, highly-doped or low-temperature-annealed ones, would deteriorate the energy transfer efficiency, which could be healed by high-temperature annealing. This work negates the traditional consensus of concentration quenching in Er:SnO2 and provides an important insight into developing efficient Er:SnO2 based infrared luminophores.

Photoluminescence enhancement from hot nitrogen-ion implanted Si quantum dots embedded within SiO2 layer

Using the novel process of hot N+-ion implantation at 800 °C into Si quantum dots (Si-QDs) with approximately 3.2 nm fabricated by hot Si+-ion implantation into an SiO2 layer and post-Ar annealing, we experimentally demonstrated that the photoluminescence intensity (IPL) of the Si-QDs increased with increasing N+-ion dose (DN+). Post-N2 high-temperature annealing without hot N+-ion implantation, as a reference process, also increased the IPL of Si-QDs, because N atoms trapped within Si-QDs, which was evaluated by secondary ion mass spectrometry, terminate the dangling bonds within Si-QDs and at the Si/SiO2 interface. Additionally, the IPL of Si-QDs showed the maximum value at the optimal DN+ of 5 × 1015 cm−2, which was 1.4-fold higher than that observed without hot N+-ion implantation. With a short post-annealing time (<60 min), the increase in IPL owing to N+-ion implantation was considerably larger than that caused by N2 annealing, which is likely due to the efficiency of the termination of the dangling bonds of the Si-QDs by the N+-ions. This is an advantage of the hot N+-ion implantation technique. Forming gas annealing after furnace annealing also induced a larger IPL than that observed before forming gas annealing. However, the maximum IPL observed after forming gas annealing was completely independent of the conditions of furnace annealing and DN+. This suggests that the perfect termination of the dangling bonds of the Si-QDs may be realized via forming gas annealing after furnace annealing.

Influence of Silicon Oxide Processes on the Performance of Copper Indium Gallium Selenide Flexible Solar Cells

Stainless steel (SS) foils have successful flexible device applications because of their excellent high‐temperature performance and commercial availability, and they are widely used as flexible substrate materials for Cu(In,Ga)Se2 (CIGS) solar cells. The method used to control metal impurities is crucial for producing high‐quality cells. Herein, CIGS precursor films are deposited on SS foils coated with a SiOx/Ti compound barrier layer by sputtering a CIGS quaternary target. The absorber layer is recrystallized at a high annealing temperature (≈600 °C). The relationship between cell performance and SiOx layer processes is investigated. The diffusion of Fe and Cr in the annealed films is influenced by SiOx layer processes. The proposed CIGS flexible cells obtain better conversion efficiency when thicker SiOx layers are deposited at high sputtering powers.

Zinc sulfide thin films deposited by chemical bath: Tuning consideration of structural, optical band gap, and electrical properties for CIGS solar cells application

Zinc sulfide (ZnS) is widely employed in a solar cell structure as a buffer layer due to its excellent physical and chemical properties. ZnS elements discovered in the earth's crust are safe. This study examined the performance characteristics of ZnS thin films deposited on soda lime glass substrate via chemical bath deposition. The ZnS thin films were annealed at temperatures of 300, 400, and 500 °C in a vacuum environment. XRD showed the ZnS thin films with high annealing temperatures are composed of a wurtzite structure. Increased annealing temperature improved crystallization, average crystallite sizes, film thickness, and low dislocation density as well as lattice strain. The FESEM analysis reveals that the morphology of annealed thin film at high temperatures has larger grains compared to the deposited films. EDS spectra confirm that zinc and sulfur are present in the ZnS thin film. Annealed films have an average transmission of 20–50 % in the visible spectrum of 300–1100 nm. Films exhibit 103 Ωcm resistivity, and the bulk carrier density ranges between 1012 and 1014 cm−3. The annealed film at 500 °C has a direct band gap of 3.47 eV, a resistivity of 1.79 × 103 Ωcm, and a bulk concentration of 1.19 × 1014 cm−3. All ZnS thin films have n-type conductivity.

Spatially confined growth of VO2(M) nanoparticles with improved thermochromic property

In the pursuit of VO2-based energy efficient smart window, high-temperature annealing is a common way to prepare well-crystallized VO2 nanoparticles (NPs) with reduced defect density. However, it is usually accompanied by the formation of oversized VO2 NPs due to Ostwald ripening, making unsatisfactory optical performances of VO2-based films. In this work, we reported a spatial confinement route via incorporating commercial fumed silica (FS) as space barrier during the process of annealing ultrafine γ-VOOH NPs, and the size of the obtained VO2 NPs could be reduced to ∼50 nm. Moreover, VO2 films based on the multilevel spatial confinement strategy exhibit outstanding optical performances with balanced solar regulation efficiency (ΔTsol ∼ 17.82 %) and luminous transmittance (Tlum ∼ 51.74 %). A simple dipping process could be carried out to enable a hydrophobic self-cleaning surface of the obtained VO2 films, which was meaningful for smart window applications. VO2@SiO2 core-shell structure, referring to a strong spatial confinement strategy, was also prepared via coating γ-VOOH NPs with SiO2 followed by annealing treatment. The top-level optical performances with ΔTsol of 20.46 % and Tlum of 44.26 % of VO2@SiO2/PVP films were achieved successfully. The spatial confinement strategy may inspire more facile and efficient processes for development of high-performance VO2 films for various applications.

Tensile failure mechanisms investigation of mesophase pitch-based carbon fibers based on continuous defective graphene nanoribbon model

Mesophase pitch (MPP)-based carbon fibers exhibit outstanding mechanical properties, notably an exceptionally high Young’s modulus. Despite extensive investigations into the microstructure of MPP-based carbon fibers, the influence of these factors on deformation mechanisms under tension remains unclear. This study employs the continuous defective graphene nanoribbons (dGNR) atomistic structure model for molecular dynamics simulations to explore the tensile failure mechanisms of MPP-based carbon fibers. In the simulation model, the structure of the defective region was generated through high-temperature annealing, and a transition region was introduced to prevent distortion and damage to the active graphene edges. The simulation reveals the evolutionary process of the microstructure of MPP-based carbon fibers under tension and achieves Young’s modulus predictions with greater accuracy than theoretical models. Additionally, the study shows that different strengths of interactions between adjacent graphene nanoribbons can lead to two distinct failure modes. Models with larger crystallite dimensions along the fiber axis and lower average defective concentrations exhibit geometric deformation coordination between adjacent nanoribbons, potentially elucidating the increasing strength trend in MPP-based carbon fibers with rising graphitization levels. Our simulations provide insights into the tensile failure mechanisms of MPP-based carbon fibers, offering valuable guidance for regulating their microstructure to enhance mechanical performance.

Molecular dynamics simulation of effect of nickel transition layer on deposition of carbon atoms and graphene growth on cemented carbide surfaces

<sec>WC-Co cemented carbide has excellent cutting performance, which is a potential tool material. But when it is used as cutting ultra-high strength and high hardness materials, the machining accuracy and service life of the tool are significantly reduced. Graphene is a potential coating material for cemented carbide cutting tools due to its excellent mechanical properties. In this work, molecular dynamics (MD) is used to simulate the deposition of nickel transition layer and high-temperature catalytic growth of graphene in cemented carbide. The Ni and C atomic deposition process and the high temperature annealing process are simulated, and a combination of potential functions is adopted to continuously simulate these two deposition processes. The effect of deposition temperature and the effect of incident energy on the growth of graphene are analyzed. The healing mechanism of nickel-based catalytic defective graphene under high-temperature annealing is explored in detail.</sec><sec>The simulation results show that at the deposition temperature of 1100 K, the coverage of graphene is higher and the microstructure is flat. The higher temperature helps to provide enough kinetic energy for carbon atoms to overcome the potential energy barrier of nucleation, thereby promoting the migration and rearrangement of carbon atoms and reducing graphene growth defects. Too high a temperature will lead to continuous accumulation of carbon atoms on the deposited carbon rings, forming a multilayered reticulation and disordered structure, which will cause a low coverage rate of graphene. The increase of incident energy helps to reduce the vacancy defects in the film, but excessive energy leads to poor continuity of the film, agglomeration, the more obvious stacking effect of carbon atoms and the tendency of epitaxial growth. When the incident energy is 1 eV, the surface roughness of the film is lower, and more monolayer graphene can be grown. During annealing at 1100 K, the carbon film dissolves and nucleates simultaneously in the Ni transition layer, and the nickel transition layer catalyzes the repair of defective graphene. The graphene film becomes more uniform, and the number of hexagonal carbon rings increases. Appropriate high-temperature annealing can help to repair and reconstruct defective carbon rings and rearrange carbon chains into rings. Therefore, when the deposition temperature is 1100 K and the incident energy is 1 eV, graphene can be deposited and annealed to grow a high-quality graphene coatings. The simulation results provide the reference for preparing the cemented carbide graphene coated tools.</sec>

The role of primary recrystallization microstructure in secondary recrystallization of Goss grain in industrial low-temperature grain-oriented silicon steel

Low-temperature grain-oriented silicon steel has very excellent magnetic properties along the rolling direction. During industrial mass production, slight process fluctuations can directly lead to variations in the primary recrystallization microstructure, which in turn can have a dramatic effect on the magnetic properties of the final product. However, it is unclear how different primary recrystallization microstructures influence the magnetic properties of the industrial final products, making it difficult to further optimize the production process of industrial low-temperature grain-oriented silicon steel. Therefore, it is very important to clarify the transformation behavior of different primary recrystallization microstructures and their influences on the transformation behavior of inhibitors during the high-temperature annealing process. Here, we analyzed the differences between two primary recrystallization microstructures in terms of microstructure homogeneity, Goss grain characteristics and texture characteristics and investigated the secondary recrystallization behavior of Goss grains and the dissolution behavior of inhibitors in these two primary recrystallization microstructures during high-temperature annealing. Based on the results of this work, it was found that a finer primary recrystallization microstructure could be more favorable to the formation of a sharp Goss texture, which in turn could significantly improve the magnetic properties, and in addition, new insights into the transformation behavior and the grain boundary pinning behavior of inhibitors during high-temperature annealing process were established. The results of this work could help to further improve the understanding of the actual role of inhibitors during high-temperature annealing and could also provide new ideas for further improving the industrial production process.

Optimization of electrical properties and radio frequency applications of GeTe thin film

GeTe belongs to a chalcogenide phase change material, which can dynamically achieve reversible switching between the crystalline state of low resistivity and the amorphous state of high resistivity by utilizing the thermally induced phase change characteristics. The GeTe is an important functional material in the fields of memristors and nonvolatile radio frequency (RF) switches. For RF switch applications, this paper focuses on optimizing the electrical performance of GeTe thin films prepared by magnetron sputtering. By comprehensively analyzing the effects of substrate materials, sputtering conditions, and annealing conditions on the resistivity of crystalline GeTe films, effective conditions for preparing low resistivity GeTe films are explored. Fig. (a) shows that compared with the GeTe film on a SiO<sub>2</sub> substrate, the film on an Al<sub>2</sub>O<sub>3</sub> substrate can obtain higher crystallinity and lower resistivity. For the deposition power and pressure shown in Fig. (b), the combination of medium power (50–80 W) and low pressure (2–3 mTorr) is beneficial for low crystalline resistivity of GeTe film. Additionally, Fig. (c) shows that higher annealing temperature (350–400 ℃) can realize lower film resistivity. Finally, the experimental results show that the lowest crystalline resistivity of the prepared GeTe thin film reaches 3.6×10<sup>–6</sup> Ω·m, and the resistance ratio is more than 10<sup>6</sup>. Based on rectangular chips of GeTe film, a parallel millimeter-wave switch with zero static power is also constructed. As shown in Fig. (d), the insertion loss is less than 2.4 dB, and the isolation is greater than 19 dB in a 1–40 GHz frequency band, demonstrating the potential application of GeTe thin films in the field of broadband high-performance discrete nonvolatile RF switches.

Enhancement of Cu2ZnSn(S, Se)4 device performance using an IPA/MOE hybrid solvent system in ambient air.

In this work, a mixed precursor solvent system comprising isopropyl alcohol (IPA) and 2-methoxy ethanol (MOE) is introduced for the fabrication of Cu2ZnSn(S, Se)4 (CZTSSe) thin films under ambient conditions. The effects of different IPA/(MOE + IPA) ratios on the characteristics of CZTSSe films and the corresponding devices were investigated. Our research results indicate that the addition of IPA enhances the wettability of Cu-Zn-Sn-S precursor solution on the substrate, reduces Sn loss in the film during high-temperature annealing, and diminishes band tail states. Additionally, adding IPA leads to effective enlargement of grain size, improved crystallinity, and enhanced light absorption. However, excessive content of IPA negatively impacts CZTSSe film properties and the device's performance. Notably, when substituting 20% of MOE with IPA, the short-circuit current density (JSC) increased from 30.84 mA cm-2 to 35.55 mA cm-2 in the resulting CZTSSe device, and the efficiency improved from 9.19% to 10.63%. This work provides a new method of a solvent system for preparing efficient kesterite-based solar cells.

Accelerating metal nanoparticle exsolution by exploiting tolerance factor of perovskite stannate.

The octahedral symmetry in ionic crystals can play a critical role in atomic nucleation and migration during solid-solid phase transformation. Similarly, octahedron distortion, which is characterized by Goldschmidt tolerance factor, strongly influences the exsolution kinetics in the perovskite lattice framework during high-temperature annealing. However, a fundamental study on manipulating the exsolution process by octahedron distortion is still lacking. In this study, we accelerate Ni metal exsolution on the surface of perovskite stannates by increasing the [BO6] octahedron distortion in the lattices. Decreasing the A-site ionic radius (rBa2+ = 161 pm → rSr2+ = 144 pm → rCa2+ = 134 pm) increased the density of exsolved Ni nanoparticles by up to 640% (i.e., 47 particles μm-2 of Ba(Sn, Ni)O3 → 304 particles μm-2 of Ca(Sn, Ni)O3) after the identical exsolution process. Based on the theoretical calculation and experimental characterization, the decrease in crystal symmetry by octahedral distortion promoted the Ni exsolution owing to the boosted Ni migration by weakening the bond strength and generating domain boundaries. The findings highlight the importance of octahedral distortion to control atomic migration through the perovskite lattice framework and provide a strategy to tailor the density of uniformly populated nanoparticles in nanocomposite oxides for multifunctional material design.

Percolation threshold in annealed ultrathin SiOx films by 2D Monte Carlo simulations

In this work, the kinetics of phase separation in ultrathin non-stoichiometric Si oxide (SiOx, x < 2) films during high-temperature annealing is studied by Monte Carlo simulations on the two-dimensional...

The AlN lattice-polarity inversion in a high-temperature-annealed c-oriented AlN/sapphire originated from the diffusion of Al and O atoms from sapphire.

AlN films are widely used owing to their superior characteristics, including an ultra-wide bandgap, high breakdown field, and radiation resistance. High-temperature annealing (HTA) makes it easy to obtain high-quality AlN films, with the advantages of a simple process, good repeatability, and low cost. However, it is always found that there is a lattice-polarity inversion from a N-polarity near the sapphire to an Al-polarity in the HTA c-oriented AlN/sapphire. Currently, the formation mechanism is still unclear, which hinders its further wide applications. Therefore, the formation mechanism of the polarity inversion and its impacts on the quality and stress profile of the upper AlN in the HTA c-oriented AlN/sapphire were investigated. The results imply that the inversion originated from the diffusion of the Al and O atoms from the sapphire. Due to the presence of abundant Al vacancies (VAl) in the upper AlN, Al atoms in the sapphire diffuse into the upper AlN during the annealing to fill the VAl, resulting in the O-terminated sapphire, leading to the N-polar AlN. Meanwhile, O atoms in the sapphire also diffuse into the upper AlN during the annealing, forming an AlxOyNz layer and causing the inversion from N- to Al-polarity. The inversion has insignificant impacts on the quality and stress distribution of the upper AlN. Besides, this study predicts the presence of a two-dimensional electron gas at the inversion interface. However, the measured electron concentration is much lower than that predicted, which may be due to the defect compensation, low polarization level, and strong impurity scattering.

Applying the Hollomon-Jaffe parameter to predict changes in mechanical properties of irradiated austenitic chromium-nickel steels during isothermal exposure

<abstract> <p>The Hollomon-Jaffe parameter is widely used in metallurgy and materials science to characterize the behavior and predict the various metals' physical-mechanical properties under different temperature and time modes. The possibility of predicting changes in the mechanical properties of structural steels due to thermal influences has been studied. The paper presents the results of a study of the mechanical properties of the materials of the core components of the BN-350 reactor facility (RF) made of austenite chromium-nickel steel 12Cr18Ni10Ti (a spent fuel assembly's jacket) and 09Cr16Ni15M3Nb (an intro-channel displacer). The samples were studied both before and after radiation annealing. Annealing of steel samples at 550 ℃ reduced the yield strength and significantly restored the plasticity and ability of the material to strain hardening. The efficiency of post-radiation annealing of the materials increases with annealing temperature and leads to a transition to the reduction process. It was established that medium of high temperature annealing during heat treatment does not lead to significant changes in the mechanical properties of irradiated materials. The microstructure studied using a scanning electron microscope reasonably correlates with the results of mechanical tests. The possibility of using the Hollomon-Jaffe parameter to predict the properties of austenite chromium-nickel steel, which received damaging doses in the range from 12 to 59 dpa, was shown for the first time. Thus, for the first time, the unique coefficient (<italic>C</italic>) of the Holloman-Jaffe parameter for irradiated materials of chromium-nickel steel was experimentally determined, and dependencies characterizing the change in hardness of chromium-nickel steel on temperature and duration of post-radiation thermal exposure were established.</p> </abstract>

On the structural evolution of nanoporous optically transparent CuO photocathodes upon calcination for photoelectrochemical applications.

Copper oxides are promising photocathode materials for solar hydrogen production due to their narrow optical band gap energy allowing broad visible light absorption. However, they suffer from severe photocorrosion upon illumination, mainly due to copper reduction. Nanostructuring has been proven to enhance the photoresponse of CuO photocathodes; however, there is a lack of precise structural control on the nanoscale upon sol-gel synthesis and calcination for achieving optically transparent CuO thin film photoabsorbers. In this study, nanoporous and nanocrystalline CuO networks were prepared by a soft-templating and dip-coating method utilizing poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic® F-127) as a structure-directing agent, resulting for the first-time in uniformly structured, crack-free, and optically transparent CuO thin films. The photoelectrochemical properties of the nanoporous CuO frameworks were investigated as a function of the calcination temperature and film thickness, revealing important information about the photocurrent, photostability, and photovoltage. Based on surface photovoltage spectroscopy (SPV), the films are p-type and generate up to 60 mV photovoltage at 2.0 eV (0.050 mW cm-2) irradiation for the film annealed at 750 °C. For these high annealing temperatures, the nanocrystalline domains in the thin film structure are more developed, resulting in improved electronic quality. In aqueous electrolytes with or without methyl viologen (as a fast electron acceptor), CuO films show cathodic photocurrents of up to -2.4 mA cm-2 at 0.32 V vs. RHE (air mass (AM) 1.5). However, the photocurrents were found to be entirely due to photocorrosion of the films and decay to near zero over the course of 20 min under AM 1.5 illumination. These fundamental results on the structural and morphological development upon calcination provide a direction and show the necessity for further (surface) treatment of sol-gel derived CuO photocathodes for photoelectrochemical applications. The study demonstrates how to control the size of nanopores starting from mesopore formation at 400 °C to the evolution of macroporous frameworks at 750 °C.

Mechanical characteristics and crystallographic texture of AA5083 during Equal Channel Angular Pressing Technique

AA5083 bars processed by four pass ambient Equal Channel Angular Pressing were subjected to intersection annealing, where time and temperature were varied after each pass. The microstructures, texturing and compressive characteristics of the samples were meticulously examined. Due to the high annealing temperatures, both ultimate tensile strength and compressive stresses decreased with increasing grain size. However, intersection annealing at room temperature resulted in the best compressive yield strength. The deformation behavior of AA5083 billets was investigated using finite element analysis. Electron back scatter diffraction was employed to examine the texture of the Equal Channel Angular Pressed billet crystals. Extensive research was conducted on the tensile properties and Vickers microhardness. The finite element simulations revealed that the 900 die exhibited a significantly more uniform dispersion of plastic strain compared to the 1200 die. The renewal of additional slip mechanisms during the four Pass process was attributed to the grain refining that occurred after the 1-Pass and 2-Pass stages. Equal Channel Angular Pressing successfully produced a homogeneously ultra-fine grained microstructure. The increase in strength was attributed to grain refining and dislocation strengthening. Molecular dynamics simulations were employed to study the ECAPed approach of AA5083 providing insights into the deformation behavior and polycrystal formation.

Suppression of phase segregations in Ge–Fe–Co–Ni–Mn films by high-entropy effect

Fe–Co–Ni–Mn films doped with different concentrations of Ge were prepared on the Si substrates by using radio frequency magnetron sputtering. Transmission electron microscopy (with an energy dispersive x-ray spectrometer) and an x-ray diffractometer were used to systematically study the microstructure evolution of the Fe–Co–Ni–Mn–Ge films. The results indicate that the Fe–Co–Ni–Mn films doped with a large amount of Ge show significant element segregation after rapid high-temperature annealing. However, with the decrease in the doping amount of Ge to approximately equal molar ratio with magnetic elements, Ge and magnetic elements achieve perfect mutual dissolution at the same annealing conditions, forming single-phase solid solution. Electrical transport tests suggest that its electrical property is close to semiconductors. The mechanism of enhanced mutual solubility between semiconductor elements and magnetic elements is discussed in detail.