Mechanical Alloying Research Articles

High Efficiency in Clean Hydrogen Production Using Water and AlLi Phases Prepared by Mechanical Alloying

In this work, the results of clean hydrogen production from the direct chemical reaction between aluminum–lithium compounds and distilled water under normal conditions, without additives or catalysts, are presented. The material was prepared by mechanical alloying using a high-energy Spex-type mill in an Al20Li ratio. Relatively short milling times were programmed for the preparation of AlLi phases. Through this process, two phases (AlLi and Al8.9Li1.1) were identified, which react efficiently to produce clean hydrogen. The experiments demonstrate fast and self-sustained reactions between AlLi phases and distilled water. In both the phase preparation and hydrogen generation, 100% efficiency was achieved. The hydrolysis reaction occurred quickly, and the hydrogen volume generated was 1700 mL/g of material. Under these conditions, aluminum generates 1390 mL of hydrogen, and lithium generates 310 mL/g from both AlLi phases. A single by-product (LiAl2(OH)7·2H2O) was identified. According to the results and the conditions applied in this research, the hydrogen produced does not require prior purification and can therefore be used directly in fuel cells. The AlLi–water reaction is a promising process for generating hydrogen in a simple and relatively short time compared to other hydrogen production methods. In this process, no greenhouse gas emissions were produced.

Effect of Dispersed ZrO2 Particles on Microstructure Evolution and Superconducting Properties of Nb-Ti Alloy

The influence of dispersed ZrO2 particles on the microstructure evolution and the superconducting properties of a Nb-Ti alloy was investigated. The studied materials were prepared by different methods including mechanical alloying (MA) and arc-melting. The obtained samples were studied by X-ray diffraction (XRD) and vibrating-sample magnetometer (VSM). It was found that ZrO2 particles can be successively introduced into an Fe-Nb matrix by MA. However, among all prepared samples with a nominal composition of Nb-47wt%Ti-5 wt% ZrO2, only the powders, which were prepared by MA of Nb-47wt%Ti and ZrO2 powders, exhibit superconductivity with critical parameters comparable to those observed in pristine Nb-47wt%Ti alloy. In particular, the determined upper critical field at 0 K μ0Hc2(0) is close to 15.6(1) T. This value is slightly higher than 15.3(3) T obtained for Nb-47wt%Ti and it can be ascribed to the presence of introduced ZrO2 particles in the Nb-Ti matrix.

Microstructural evolution and high temperature hot corrosion behaviour of AlCoCrFeNiTi high-entropy alloy coatings

The fuels used contain undesirable impurities such as Na, V, K, S, and Mg in gas turbine engines. These impurities react with hot components under service conditions, leading to the deterioration of the thermal barrier coatings (TBCs) structure and the formation of hot corrosion damage. In this study, metallic powders containing CoNiCrAlY were deposited as bond coat on Inconel 718 superalloy material using high velocity oxygen fuel (HVOF) coating technique. High entropy alloy (HEA) powder containing AlCoCrFeNiTi was synthesized as coating material using mechanical alloying (MA) method. AlCoCrFeNiTi powders were produced using atmospheric plasma spray (APS) coating technique. The produced coating system was subjected to hot corrosion tests at 700 °C and 800 °C temperatures for different time periods in corrosive environment conditions containing Na2SO4 (sodium sulfate) and V2O5 (vanadium pentoxide). Hot corrosion behavior of the coating system was determined, damage formations and degradation processes were investigated in detail. As a result of the determination and synthesis of HEA powder materials, production of coatings, experimental studies and hot corrosion test studies under service conditions, it was seen that the Ti-containing AlCoCrFeNi HEA coating system has usable qualities without any damage such as cracking, buckling or spalling.

Study of Phase Evolution and Phase Stability in a Novel FCC Based Al30Ti35Mg5V10Fe8Cr12 Lightweight High-Entropy Alloy Processed by Mechanical Alloying

Study of Phase Evolution and Phase Stability in a Novel FCC Based Al30Ti35Mg5V10Fe8Cr12 Lightweight High-Entropy Alloy Processed by Mechanical Alloying

Structural Transition and Magnetic Property of Quasicrystalline Phases in Al–Cu–Fe–Cr Prepared by Mechanical Alloying and Heat Treatment

Structural Transition and Magnetic Property of Quasicrystalline Phases in Al–Cu–Fe–Cr Prepared by Mechanical Alloying and Heat Treatment

Microstructure and mechanical properties of CuCrFeNi medium entropy alloys synthesized via mechanical alloying and spark plasma sintering

In this study, two novel Co-free medium entropy alloys (MEAs) with compositions of Cu20Cr10Fe35Ni35 (Cu20) and Cu10Cr20Fe35Ni35 (Cu10) were successfully prepared by a combination of mechanical alloying (MA) and spark plasma sintering (SPS). The Cu20 alloy exhibited a heterogeneous microstructure consisting of coarse and ultrafine grains (UFG) with a face-centered cubic (FCC) structure. In contrast, the Cu10 alloy showed a homogeneous UFG microstructure with an FCC matrix and a small amount of BCC phase. Moreover, both alloys contained a small amount of Cr7C3 particles, introduced by milling media during MA. In comparison with the Cu20 alloy, the Cu10 alloy exhibited better tensile properties, e.g., yield strength of 712 MPa, ultimate tensile strength of 843 MPa, and elongation of 20.1 %, demonstrating an excellent balance between strength and ductility compared to some well-established FCC-structured multi-component MEAs and high entropy alloys (HEAs). The enhanced tensile properties of the Cu10 alloy are attributed to the synergistic effects of grain refinement and Orowan strengthening by the fine Cr7C3 particles. The findings of this work provide valuable insights for designing cost-effective HEAs and MEAs with high strength and desirable ductility for various structural applications.

Sixty Years of Mechanical Alloying—Past Achievements, Current Challenges, and Future Prospects

Mechanical alloying (MA), a completely solid‐state high‐energy powder processing method, was initially used to develop Ni‐based and Fe‐based superalloys containing oxide dispersions for applications at high temperatures and requiring high strength. MA is currently an established materials process to synthesize a variety of nonequilibrium alloys with unique microstructures and properties. Supersaturated solid solutions, metastable intermediate phases, amorphous alloys, quasicrystalline alloys, nanostructures, and nanocomposites, and high‐entropy alloys are some of the materials developed using MA. These advanced structural and functional materials exhibit great potential with widespread applications. Several new and novel applications have also been recently developed. A major concern in using this technique to produce advanced materials is the inherent contamination experienced by the milled powder. In the present article, the past achievements during the last 60 years and current challenges are described in brief. Methods to decrease powder contamination and ways to reduce the cost of powders produced are also discussed. It is also shown that while the MA concept is straightforward, the outcome of the process can be stochastic, depending on many variables which must be experimentally determined since no comprehensive process model exists. The article concludes with the future prospects of this materials processing technique.

Microstructural and Morphological Properties of AlNiCo and CoNi Alloys: An In-Depth Study Based on Low-Energy Mechanical Alloying

This study focused on synthesizing AlNiCo and CoNi materials using a low-energy milling process. The aim was to explore the formation of low-energy phases in both systems, contrasting with the typical research on phases formed under high-energy conditions. In the Co-20 wt% Ni system, the phases Co0.75Ni0.25 and Ni were identified, as well as the FCC cubic phase of CoNi, using X-ray diffraction (XRD) with a molybdenum radiation source. The observed behavior aligned closely with the miscibility curve in the equilibrium phase diagram, which included a region of alloys with varying structures and similar compositions. A notable feature was the presence of a predominantly dispersed hexagonal Ni zone, consisting of nanoparticles. Transmission electron microscopy (TEM) was employed to observe the FCC CoNi phase, which displayed a specific arrangement. AlNiCo and CoNi alloys were successfully synthesized through mechanical alloying, incorporating equilibrium and non-equilibrium phases.

Microstructural and Magnetic Characteristics of High-Entropy FeCoNiMnTi Alloy Produced via Mechanical Alloying

In the current study, X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer techniques were used to examine the impact of milling time on the microstructural and magnetic characteristics of Fe30Co20Ni20Mn20Ti10 (at%) produced via mechanical alloying. Results demonstrate that phase change is dependent on up to 30 h of milling. In terms of the hcp-Fe2Ti intermetallic and the BCC-FeCoNiMnTi supersaturated solid solution, the system maintains its two-phase structure at higher times. Additionally, the final average crystallite size was estimated to be approximately 10 nm, and the lattice strain was found to be between 0.95 and 1.15 %. As a function of milling time, the magnetic properties are discussed with the microstructural and crystallographic alterations. The collected powder after 100 h of milling has an Ms value of 28 emu/g and a Hc value of 25 Am−1, which is consistent with exceptional soft magnetics. This is essentially due to the Fe2Ti intermetallic and the BCC-Fe-based solid solution production, together with the refinement of the crystallite size. Furthermore, the presence of paramagnetic Ti atoms in solid solution and the development of high densities of defects and interfaces have been connected to the low value of Ms.

Nanocrystalline/Amorphous Tuning of Al-Fe-Nb (Mn) Alloy Powders Produced via High-Energy Ball Milling.

The demand for advanced Al-based alloys with tailored structural and magnetic properties has intensified for applications requiring a high thermal stability and performance under challenging conditions. This study investigated the phase evolution, magnetic properties, thermal stability, and microstructural changes in the Al-based alloys Al82Fe16Nb2 and Al82Fe14Nb2Mn2, synthesized via mechanical alloying (MA), using stearic acid as a process control agent. The X-ray diffraction results indicated that Al82Fe16Nb2 achieved a β-phase solid solution with 13-14 nm crystallite sizes after 5 h of milling, reaching an amorphous state after 10 h. In contrast, Al82Fe14Nb2Mn2 formed a partially amorphous structure within 10 h, with enhanced stability with additional milling. Magnetic measurements indicated that both alloys possessed soft magnetic behavior under shorter milling times (1-5 h) and transitioned to hard magnetic behavior as amorphization progressed. This phenomenon was associated with a decrease in saturation magnetization (Ms) and an increase in coercivity (Hc) due to structural disorder and residual stresses. Thermal stability analyses on 10 h milled samples conducted via differential scanning calorimetry showed exothermic peaks between 300 and 800 °C, corresponding to phase transformations upon heating. Post-annealing analyses at 550 °C demonstrated the presence of phases including Al, β-phase solid solutions, Al₁3Fe₄, and residual amorphous regions. At 600 °C, the Al3Nb phase emerged as the β-phase, and the amorphous content decreased, while annealing at 700 °C fully decomposed the amorphous phases into stable crystalline forms. Microstructural analyses demonstrated a consistent reduction in and homogenization of particle sizes, with particles decreasing to 1-3 μm in diameter after 10 h. Altogether, these findings highlight MA's effectiveness in tuning the microstructure and magnetic properties of Al-Fe-Nb (Mn) alloys, making these materials suitable for applications requiring a high thermal stability and tailored magnetic responses.

Microstructure and mechanical properties of Cu-Ti alloy by mechanical alloying

In this paper, Cu-Ti alloy powder with Ti content of 2%, 2.5%, 3% and 3.5% was prepared by mechanical alloying method, and then Cu-Ti alloy powder was formed using vacuum hot pressing sintering method to prepare Cu-Ti alloy. The results show that the complete mechanical alloying time of Cu-2%Ti, Cu-2.5%Ti, Cu-3%Ti and Cu-3.5%Ti is 1h, 1h, 1.5h and 2h, respectively. Cu-Ti alloys with different Ti contents prepared by vacuum hot pressing sintering, the comprehensive properties of Cu-2.5%Ti are better, with electrical conductivity of 33.42%IACS and tensile strength of 385 MPa, which is 193.5% higher than that of pure copper. The hardness is 201.66HV, 331.1% higher than that of pure copper.

Improving electromagnetic wave absorption performance by adjusting the proportion of brittle BCC phase in FeCoNiCr0.4Mnx high-entropy alloys

High-entropy alloys, as a novel type of absorber, exhibit exceptional electromagnetic modulation capabilities and significant potential for electromagnetic wave absorption. In this work, the FeCoNiCrMn high-entropy alloy absorbent prepared through a mechanical alloying process demonstrates a dual-phase solid solution structure comprising face-centered cubic (FCC) and body-centered cubic (BCC) phases. By varying the manganese (Mn) content in the system, it is possible to enhance the degree of crystallinity, maintain the integrity of the crystal structure, and effectively control the relative proportion of the BCC phase within the overall phase composition. This adjustment improves the brittleness of the sheet-like particles, reduces particle size, and significantly lowers the permittivity. When the molar ratio of Mn is 0.6, the sample exhibits improved impedance matching due to the optimal permittivity and permeability. Notably, the impedance matching and attenuation constant can also be balanced. At 6.42 GHz, the FeCoNiCr0.4Mn0.6 alloy powder achieves the maximum reflection loss of −48.49 dB at a matching layer thickness of 3 mm. When the matching thickness is reduced to 2 mm, it can effectively cover a frequency range of 8.7–14.1 GHz (effective absorption bandwidth of 5.4 GHz), along with a wide absorption bandwidth and high absorption efficiency.

Effect of precursor state on the formation of triphase (SmCo7 + SmCo3)/Fe(Co) magnets

The combination of fabrication of a precursor and subsequent thermal treatments is an effective strategy for crafting multi-phase SmCo-based nanocomposite magnets. However, a comprehensive understanding of the effect of precursor state on the formation of multiphase magnets has yet to be fully explored. In this study, Sm(CoFeCuZr)/Fe(Co) of precursors were prepared via mechanical alloying. The precursor state was tailored by adjusting the ball milling process, as well as the content and composition of soft magnetic phase. The amorphization degree of the SmCo phase, the atomic ratio of Sm:Co in the SmCo alloy, and the content of Fe(Co) in the precursor increase with the increasing ball milling time, the increase in the content of the soft phase and the proportion of Fe within the soft phase. And this resulted in an increase in the content of Fe(Co) and SmCo3 phases but a decrease in the content of SmCo7 phase in samples annealed at 400–720 °C. This further led to an increase in the saturation magnetization and a decrease in the coercivity of the triphase (SmCo7 + SmCo3)/Fe(Co) magnet. The mechanisms responsible for the precursor state control and the formation of the triphase magnet were investigated.

Structure and properties of Fe40Mn20Cr20Ti10Al10 high-entropy alloy fabricated by mechanical alloying and spark plasma sintering

Structure and properties of Fe40Mn20Cr20Ti10Al10 high-entropy alloy fabricated by mechanical alloying and spark plasma sintering

Effect of Precipitation Heat Treatment on a Mechanically Alloyed Al‐Based Composite Reinforced with Metallic Glassy Powder

An Al‐based composite reinforced with titanium‐based metallic glassy particles is synthesized by the powder metallurgy method through mechanical alloying followed by hot extrusion. The effect of precipitation heat treatment on the structure and properties of the composite is studied. During aging of the solution‐treated composite, crystallization of the metallic glassy reinforcement becomes more pronounced as the solutionizing temperature, solutionizing time, aging temperature, and aging time increase. A reaction layer has formed at the interface between the reinforcement and the matrix after the aging treatment. It is found that the addition of metallic glassy particles promotes precipitation of the nanophase in the matrix. With appropriate heat treatment, the compressive strength, yield strength, and fracture strain of the composite have increased to 942, 635 MPa, and 27%, respectively. Herein, it is demonstrated that the mechanical properties of these composites can be further enhanced through an appropriate heat treatment process, thereby having significant potential for a variety of industries, including aerospace, automotive, and defense, where high‐strength, lightweight materials are critical for performance and safety.

High entropy alloy reinforcement for superior electromagnetic interference shielding performance in carbon fiber‐reinforced polymer composites

AbstractThis study explores the enhancement of electromagnetic interference (EMI) shielding effectiveness (SE) in carbon fiber‐reinforced polymer (CFRP) composites through the integration of equatomic CoCuFeNi high entropy alloy (HEA) particles. Employing mechanical alloying (MA), CoCuFeNi HEA powders were synthesized, revealing a face‐centered cubic structure with crystallite and particle sizes of 14.7 nm and 11.62 μm, respectively. The integration of these HEA particles at concentrations of 5%, 10%, and 15% by weight into epoxy resin, followed by the fabrication of composites using the hand lay‐up technique. Detailed structural analysis of HEA particles confirmed the successful synthesis of equatomic HEAs via MA. Structural analysis of the HEA integrated composites revealed vacancy regions at 5% concentration, a uniform distribution at 10%, and particle agglomeration causing inhomogeneity and vacancies at 15%. The composites demonstrated significant improvements in EMI SE, with the 10% HEA sample showing superior performance compared to the other samples. Specifically, the 10% HEA composite achieved a peak SE of 73.09 dB at 4.72 GHz, attributed to the optimized distribution of HEA particles that enhanced electrical conductivity and reflective properties.Highlights CoCuFeNi HEA particles were successfully synthesized via MA. HEA particles were added to epoxy at 5, 10, and 15 wt% for composite fabrication. Voids were observed in HEA5, uniformity in HEA10, and clustering in HEA15. EMI shielding was assessed using VNA, SE, dielectric permittivity, and magnetic permeability. The HEA10 composite achieved peak EMI shielding, 73.09 dB at 4.72 GHz.

Ultra-high molecular weight polyethylene filled with iron by mechanical alloying

The ultra high molecular weight polyethylene (UHMWPE) shows properties that provide wide industrial and technological interest. To study the influence of iron particles on UHMWPE, the polymer was filled with Fe-powder in different stoichiometries through mechanical alloying (MA). The MA resultant samples were subjected to various analyses aiming at the characterization of mechanical, structural, and hyperfine properties. The tensile test indicated a small change in the stress-strain curves, this change was related to the yield stress. The X-ray diffraction showed the presence of a monoclinic phase, a metastable phase induced by deformation. Mössbauer spectroscopy pointed at the presence of three iron sites: metallic iron, Fe2+ e Fe3+. Considering these results, it is possible to ascertain that the iron weakly changes some properties of the polymer without degradation. There is a clear indication that iron atoms interact with carbon atoms, between the polymer chains, creating cross-links.

Improvement of microwave absorbing capability on the soft magnetic/hard magnetic/perovskite composites

Abstract This paper reports an increase in the ability to absorb microwaves from a composite made of combination between soft and hard magnetic materials, perovskite material, and an epoxy as matrix of composite, Ni0.5Zn0.5Fe2O4/Ba0.6Sr0.4Fe9.5Al0.5MnTiO19/FeTiO3/epoxy (NBFE) with a wt% ratio of 5:3:2:10. Composite samples were made using the mechanical alloying method with milling techniques and sintered at a temperature of 1000 °C for 5 h. NBFE composites were studied to increase the ability to absorb microwaves at 2–18 GHz frequencies with thickness variations of 1 mm and 2 mm. The results obtained, the composite sample Ni0.5Zn0.5Fe2O4/Ba0.6Sr0.4Fe9.5Al0.5MnTiO19/FeTiO3/epoxy has the ability to absorb microwaves with the best reflection loss value −37.47 dB with a bandwidth almost reaches 11.32 GHz in the 2–18 GHz frequency range.

Structure and corrosion behavior of FeCoCrNiMo high-entropy alloy coatings prepared by mechanical alloying and plasma spraying

Structure and corrosion behavior of FeCoCrNiMo high-entropy alloy coatings prepared by mechanical alloying and plasma spraying

Influence of Cu and Co addition on metallurgical and wear characteristics of AlCrFeNi high entropy alloy

The creation of new alloys with improved qualities has become essential in modern industries for high-performance materials. This work’s main objective is to use vacuum arc melting (VAM) to synthesize two different high-entropy alloys (HEAs): AlCrFeNiCu and AlCrFeNiCo. The mechanical properties, phase composition, grain boundaries, and alloy composition of the HEAs were studied. The predominant crystal structure, the Body-Centred Cubic (BCC) phase was obtained for both alloys. Significantly, the Co-containing HEA showed a smaller particle size than the Cu-containing HEA, which led to a 14.21% increase in microhardness. It indicates that the Co-based HEA will likely perform better than the Cu-based HEA in applications prone to abrasion, and indentation, and requiring high hardness levels based on the observed microstructure and hardness parameters. According to wear surface morphology studies, main effects analysis and ANOVA show that increasing loads and sliding distances increase wear rate, whereas sliding velocity has less effect. The best wear rate-reducing parameters are 10 N, 0.5 m/s, and 500 m for Cu-containing HEAs, and the same can be predicted using regression analysis. The study categorizes the intricate worn surface structure by describing different surface properties and wear mechanisms, such as grooves, delamination, adhesive wear, and pitting.