Subsequent Ball Milling Research Articles

Nanosized boron nitride-incorporated polyvinyl alcohol composites with TEMPO-oxidized cellulose nanofibers as ultrathin thermal interface materials

With the miniaturization and dense packing of electrical devices and mobility platforms, the effective thermal management at the interfaces of components in compact form factors is essential to overcome the performance limits and ensure the stability. Herein, we report the development of assembly of nanosized boron nitrides (BN) and TEMPO-oxidized cellulose nanofibers (T-CNFs) in polyvinyl alcohol (PVA) composites as ultrathin thermal interface materials (TIMs). BN nanoparticles (average thickness of 3.8–4.0 nm, lateral size of 90–100 nm, and aspect ratio of 25) were produced with a yield exceeding 80 % from the chemical treatment of hexagonal BN with NaOH and subsequent ball milling. TEMPO-oxidized cellulose nanofibers (T-CNFs) were added to mechanically reinforce the PVA-based matrix, while by the functionalization with OH– groups, the BN particles dispersed readily in the PVA solution, obtaining ultrathin nanosized BN/PVA/T-CNF composite films (∼50 µm). In contrast to the expected low thermal conductivity due to surface defects and high contact resistances typical of nanosized BN, composite films containing 50 wt% nanosized BN exhibited significantly high in-plane and through-plane thermal conductivities of 11.13 and 1.22 W/mK, respectively. Comparative analysis based on the Lewis–Nielsen model revealed that the size, shape, and agglomeration state of the BN particles could highly influence the thermal conductivity of composite films. Furthermore, heat dissipation experiments reflecting practical conditions demonstrated the outstanding performance and thermal stability of nanosized BN/PVA/T-CNF films as TIMs. This study will inspire rational strategies to facilely incorporate nanosized BN to diverse composites, offering advanced thermal characteristics with mechanical robustness.

Irreducible IrO2 Anode Co-Catalysts for PEM Fuel Cell Voltage Reversal Mitigation and Their Stability Under Start-Up/Shut-Down Conditions

IrO2 has been widely used as the anode co-catalyst for mitigating cell voltage reversal damages in proton exchange membrane fuel cells (PEMFCs). However, under the PEMFC anode operation conditions, conventionally prepared IrO2 catalysts are reduced by H2, forming metallic Ir on their surface, which is prone to dissolution during start-up/shut-down (SUSD) cycles. The dissolved Irn+ ions can permeate through the membrane to the cathode electrode, poisoning the oxygen reduction reaction (ORR) activity of the Pt/C cathode catalyst. In this study, we introduce an unprecedented approach to synthesize IrO2 catalysts (irr-IrO2) which are not reduced in the PEMFC anode environment at 80 °C over extended time. Their preparation is based on an industrially scalable procedure, consisting of a high-temperature (650 °C–1000 °C) heat treatment step, a subsequent ball milling step, and a final post-annealing step, thereby attaining catalysts with specific surface areas of ∼25 m2 g−1. The high reduction resistance of the irr-IrO2 catalysts, attributed to their highly ordered crystalline structure compared to that of typically synthesized IrO2 catalysts, is reflected by the observation that SUSD cycling of MEAs with the irr-IrO2 as anode co-catalysts does not result in iridium dissolution and the associated iridium poisoning of the Pt/C cathode catalyst.

Creating value added nano silicon anodes from end-of-life photovoltaic modules: recovery, nano structuring, and the impact of ball milling and binder on its electrochemical performance

Recovery of silicon from end-of-life photovoltaic (PV) modules, purification, conversion to nano silicon (nano-Si), and subsequent application as an anode in lithium-ion batteries is challenging but can significantly influence the circular economy. Currently, a complete technology consisting of cross-contamination-free recovery of silicon wafers from end-of-life PV modules, a low-cost environmentally friendly purification process of the recovered PV silicon, a high yield conversion process of the recovered PV silicon into nano-Si, and its subsequent application in lithium-ion batteries is unavailable. This study provides a complete package including cross-contamination-free recovery, economical purification, reliable conversion to nano-Si, and efficient application of the end-of-life PV nano-Si in lithium-ion batteries. Hydrofluoric acid-free recovery and purification processes are demonstrated which can deliver large quantities of high-purity (≥ 99) silicon. In addition, the subsequent ball milling process produces very distinct nano-Si with different shapes and sizes. This study also creates a very effective nano-Si anode through in-situ crosslinking of water-soluble carboxymethyl cellulose and poly (acrylic acid) precursors. The integration of distinct PV nano-Si and water-soluble carboxymethyl cellulose-poly (acrylic acid) crosslink binder opens distinct possibilities to develop silicon-based practical anode for next generation low-cost lithium-ion batteries to power cell phones to electric vehicles.

Tuning the bandgap of 2D metallic Zn nanostructures

The semiconducting behavior of two-dimensional (2D) metal nanostructures has recently attracted much interest for their possible applications in optoelectronics and others. In particular, tuning the bandgap of such nanostructures can open up a new avenue for fabricating functional nano-devices. In the present article, we report the synthesis of 2D metallic Zn nanosheets at room temperature using a ball mill, which is capable of producing large-scale materials in a single run. Initially, nanoplates were formed for ball milling the octahedral-shaped Zn nanoparticles for the time of milling of 6 h. Subsequent ball milling for another 6 h leads these nanoplates to nearly uniform nanosheets. The thickness of these 2D nanostructures was found to decrease with an increase in the time of milling. Visible photoluminescence (PL) emissions centered at ∼3, ∼2.9, and ∼2.75 eV were observed from all the Zn particles showing semiconductor behavior. The origin of such semiconductor behavior was explained based on the radiative transition of electrons from the sp band to the upper states of the 3d band. This argument was confirmed through the studies of photoelectron spectroscopy and the first principle calculations employing density functional theory (DFT). Furthermore, excitation-dependent PL studies indicated that the bandgap of the 2D Zn nanostructures decreased with the increase in the ball milling time. Therefore, a redshift in the bandgap was observed with the increase in the ball milling time. Such changes in the bandgap with the thickness of 2D Zn nanostructures were also verified from the studies of DFT. Thus, the present study demonstrated that the bandgap of 2D metallic Zn nanostructures could be effectively tuned by reducing the thickness.

Integrated pretreatment of poplar biomass employing p-toluenesulfonic acid catalyzed liquid hot water and short-time ball milling for complete conversion to xylooligosaccharides, glucose, and native-like lignin

This work aimed to study an integrated pretreatment technology employing p-toluenesulfonic acid (TsOH)-catalyzed liquid hot water (LHW) and short-time ball milling for the complete conversion of poplar biomass to xylooligosaccharides (XOS), glucose, and native-like lignin. The optimized TsOH-catalyzed LHW pretreatment solubilized 98.5% of hemicellulose at 160 °C for 40 min, releasing 49.8% XOS. Moreover, subsequent ball milling (20 min) maximized the enzymatic hydrolysis of cellulose from 65.8% to 96.5%, owing to the reduced particle sizes and cellulose crystallinity index. The combined pretreatment reduced the crystallinity by 70.9% while enlarging the average pore size and pore volume of the substrate by 29.5% and 52.4%, respectively. The residual lignin after enzymatic hydrolysis was rich in β-O-4 linkages (55.7/100 Ar) with less condensed structures. This lignin exhibited excellent antioxidant activity (RSI of 66.22) and ultraviolet absorbance. Thus, this research suggested a sustainable waste-free biorefinery for the holistic valorization of biomass through two-step biomass fractionation.

Impact of Ball Milling on the Hydrogen Evolution Performance of Cu2Sn0.38Ge0.62S3 Photocatalytic Particles Synthesized via a Flux Method.

Ball milling has been shown empirically to produce fine photocatalytic particles from large bulky particles but to drastically reduce the photocatalytic activity of such material during water splitting due to mechanical damage to the photocatalyst surfaces. If the damaged photocatalyst surfaces could be removed or reconstructed, the reduced particle sizes resulting from milling would be expected to provide enhanced photocatalytic activity. In the present study, fine particles of crystalline Cu2Sn0.38Ge0.62S3 (CTGS), which is responsive to long wavelength light up to the near-infrared region, were synthesized by a flux method and subsequent ball milling. A photocathode made of such particles showed significantly enhanced photoelectrochemical (PEC) performance under simulated sunlight while the photocatalytic hydrogen evolution activity of a powder suspension system made from the same material exhibited a typical decrease. The CTGS crystalline particles synthesized using the flux method were found to be highly crystalline but to have relatively large micrometer-scale sizes. Ball milling reduced the particle size but produced an amorphous coating of oxidized species that lowered the photocatalytic activity of the powder suspension system. Typical surface modifications of a photocathode made from this material, consisting of wet chemical processes, also served as an etching treatment to successfully remove the minimally crystalline surface layer and provide greater PEC activity. These data suggest the benefits of combining flux crystal growth with ball milling and the appropriate chemical etching process to obtain high-crystallinity fine photocatalytic particles responsive to long wavelength light with improved PEC hydrogen evolution activity.

Manufacturing and Characterization of Dental Crowns Made of 5-mol% Yttria Stabilized Zirconia by Digital Light Processing.

We herein report manufacturing of dental crowns made of 5-mol% yttria partially stabilized zirconia (5Y-PSZ) with desired mechanical properties, optical translucency and dimensional accuracy using digital light processing (DLP). To this end, all processing parameters were carefully controlled and optimized. First, 5Y-PSZ particles with a bimodal distribution were prepared via calcination of as-received granules and subsequent ball-milling and then used to formulate 5Y-PSZ suspensions with a high solid loading of 50 vol% required for high densification after sintering. Dispersant content was also optimized. To provide high dimensional accuracy, initial dimensions of dental crowns for 3D printing were precisely determined by considering increase and decrease in dimensions during photopolymerization and sintering, respectively. Photopolymerization time was also optimized for a given layer thickness of 50 μm to ensure good bonding between layers. A multi-step debinding schedule with a slow heating rate was employed to avoid formation of any defects. After sintering at 1500 °C for 2 h, 5Y-PSZ could be almost fully densified without noticeable defects within layers and at interfaces between layers. They had high relative densities (99.03 ± 0.39%) with a high cubic phase content (59.1%). These characteristics allowed for achievement of reasonably high mechanical properties (flexural strength = 625.4 ± 75.5 MPa and Weibull modulus = 7.9) and % transmittance (31.4 ± 0.7%). In addition, 5Y-PSZ dental crowns showed excellent dimensional accuracy (root mean square (RMS) for marginal discrepancy = 44.4 ± 10.8 μm and RMS for internal gap = 22.8 ± 1.6 μm) evaluated by the 3D scanning technique.

Remarkable kinetics of novel Ni@CeO2–MgH2 hydrogen storage composite

Magnesium hydroxide (MgH2) has excellent reversibility and high capacity, and is one of the most promising materials for hydrogen storage in practical applications. However, it suffers from high dehydrogenation temperature and slow sorption kinetics. Rare earth hydrides and transition metals can both significantly improve the de/hydrogenation kinetics of MgH2. In this work, MgH2–Mg2NiH4–CeH2.73 is in-situ synthesized by introducing Ni@CeO2 into MgH2. The unique coating structure of Ni@CeO2 facilitates homogeneous distribution of synergetic CeH2.73 and Mg2NiH4 catalytic sites in subsequent ball milling process. The as-fabricated composite MgH2-10 wt% Ni@CeO2 powders possess superior hydrogenation/dehydrogenation characteristics, absorbing 4.1 wt% hydrogen within 60 min at 100 °C and releasing 5.44 wt% H2 within 10 min at 350 °C. The apparent activation energy of MgH2-10 wt% Ni@CeO2 is determined to be 84.8 kJ/mol and it has favorable hydrogen cycling stability with almost no decay in capacity after 10 cycles.

Effect of particle size on the physicochemical and antioxidant properties of Forsythia suspensa (Thunb.)Vahl leaf powders

Four powders of Forsythia suspensa leaf were prepared by coarse grinding and subsequent ball milling. The effects of particle size on the physicochemical and antioxidant properties of the powders were evaluated. The results showed that the particle size of the powder decreased from 107.99 to 29.20 μm by ball milling for 5 h. In addition, the ball-milled powders had substantial advantages in water holding, solubility and swelling capacities. Thus, the ball-milled powders had a better dissolution of phenolic, flavonoid, and polysaccharide components (25.45, 1.99 and 44.19 mg/g of powder for 5 h of ball milling), ultimately resulting in a superior antioxidant activity (maximum reductions of 14.96% and 19.20% for DPPH and ABTS radicals, respectively). The FTIR analysis showed that the structure of the active ingredients remained intact after ball milling. In conclusion, ball milling is a promising technique for preparing Forsythia suspensa leaf powder with improved physicochemical and biological properties. • Forsythia suspensa powders were obtained by coarse grinding and ball milling. • The properties and activities of the powder are correlated with the milling time. • The hydration properties of ball-milled powders rise with decreasing particle size. • Decline of the flow and thermal properties after ball milling treatment was found. • Antioxidant activity enhanced with higher active ingredients of ball-milled powders.

Low-Temperature-Graphitized and Interpenetrating Network C/Fe3O4 Magnetic Nanocomposites with Enhanced Tribological Properties under High Temperature.

Although the core-shell structure magnetic nanocomposites have been widely used as lubricant additives, their tribological properties are still poor under high temperature and high load. Herein, the graphitized C/Fe3O4 magnetic nanocomposites (g-C/Fe3O4) with an interpenetrating network structure were successfully fabricated by an in situ hydrothermal carbonization method combined with a subsequent ball milling process at room temperature. The results showed that the ball milling process not only promoted the transformation of graphitized carbon but also effectively eliminated the interfacial effect between carbon and Fe3O4. Moreover, the g-C/Fe3O4 used as a lubricant additive in rapeseed oil exhibited excellent tribological properties and high thermo-stability under 155 °C and 980 N, with the friction coefficient reduced by 32.8% compared to the independent Fe3O4. The enhanced tribological performance of g-C/Fe3O4 could be attributed to the graphitized carbon and its interpenetrating network structure under low load force (392 N), while under high load force (980 N), it could be ascribed to the synergistic effect between the graphitized carbon and magnetic Fe3O4 nanoparticles. This work not only offers a method for the synthesis of nanocomposite lubricant additives but also shows great potential in practical applications for high-temperature tribology.

A Spinel (FeNiCrMnMgAl)3O4 High Entropy Oxide as a Cycling Stable Anode Material for Li-Ion Batteries

Recently, high entropy oxides (HEO) with special stabilization effects have been widely investigated as new anode materials for lithium-ion batteries. However, the lithium storage mechanism of HEO is still under debate. In this work, we applied a modified solution combustion synthesis method with a subsequent ball milling refinement process to prepare a six-component (FeNiCrMnMgAl)3O4 spinel high entropy oxide (6-SHEO). The novel 6-SHEO anode features outstanding electrochemical performance, enabling a stable capacity of 657 mAh g−1 at a current rate of 0.2 A g−1 after 200 cycles, and good high-rate capability with 350 mAh g−1 even at 4 A g−1. In addition, the lithium storage behavior of this 6-SHEO anode was explored in detail through in-situ XRD and ex-situ TEM approaches. Surprisingly, a reversible spinel to rock salt phase transition behavior and spinel phase residue phenomenon was firstly observed by this route. Furthermore, for better understanding of the phase change behavior in this 6-SHEO anode, a high-energy ball milling approach was applied to induce a similar spinel to rock salt phase transformation for the first time, which generates fresh insight into the mechanism of the phase change behavior in this 6-SHEO anode.

Ultrafine SnSSe/multilayer graphene nanosheet nanocomposite as a high-performance anode material for potassium-ion half/full batteries

Layer-structured SnSSe attracts much attention as an anode material for potassium storage due to its large theoretical capacity. Unfortunately, their practical application is severely restrained by the dramatic volumetric variation of SnSSe. Herein, we synthesize ultrafine SnSSe/multilayer graphene nanosheet (SnSSe/MGS) by a vacuum solid-phase reaction and subsequent ball milling. Owing to the strong synergistic effect between the two components, the obtained SnSSe/MGS nanocomposite exhibits a high reversible capacity (423 mAh g−1 at 100 mA g−1), excellent rate property (218 mAh g−1 at 5 A g−1), and stable cycling performance (271 mAh g−1 after 500 cycles at 100 mA g−1) in potassium-ion half batteries. Moreover, the full cell assembled by the SnSSe/MGS anode and the potassiated 3,4,9,10-perylene-tetracarboxylic aciddianhydride cathode shows excellent electrochemical performance between 0.2 and 3.3 V (209 mAh g−1 at 50 mA g−1 after 100 cycles). The presented two-step synthesis strategy of SnSSe/MGS may also provide ideas to craft other alloy-type anode materials.

Comparison of the effects of incineration, vacuum pyrolysis and dynamic pyrolysis on the composition of NMC-lithium battery cathode-material production scraps and separation of the current collector

The rising demand for lithium batteries is challenging battery producers to increase their production. This is causing an accumulation of production scrap which must be treated to allow re-utilization of cathode material in production. Several industrial lithium battery recycling processes use thermal pre-treatment in an oxidative or inert atmosphere, or in a vacuum, to separate the battery components and remove organic material. However, a comparison of the effects of incineration, dynamic pyrolysis (under a constant flow of inert gas), and pyrolysis under vacuum on the microstructure and composition of scrap cathode material has not been explored.Scrap cathodes, with active material based on Li(NixMnyCoz)Oj, were subjected to incineration, dynamic pyrolysis, and pyrolysis under vacuum at 450˚, 550˚, and 650°C for 30, 60, 90, and 150 min to determine the best approach to cathode material recovery. While the incineration did not cause any chemical transformation of cathode material, under pyrolysis conditions the organic components in the cathodes triggered carbothermic reduction of the active material, yielding Co3O4, NiO, Mn3O4, and Li2CO3 as products. In the gas by-products, formed from the decomposition of the organic material, CO, CO2, and HF were determined. The decomposition especially of the binder in polyvinylidene fluoride (PVDF) facilitated the separation of the active material from the current collector by mechanical treatment. By subsequent ball milling, the best technique to recover cathode material is the incineration at a temperature higher than 550˚ C and below 650˚ C for at least 90 min, with >95% of recovered active material.

Influence of Structural Defects on the Properties of Metamagnetic Shape Memory Alloys

The production of μ-particles of Metamagnetic Shape Memory Alloys by crushing and subsequent ball milling process has been analyzed. The high energy involved in the milling process induces large internal stresses and high density of defects with a strong influence on the martensitic transformation; the interphase creation and its movement during the martensitic transformation produces frictional contributions to the entropy change (exothermic process) both during forward and reverse transformation. The frictional contribution increases with the milling time as a consequence of the interaction between defects and interphases. The influence of the frictional terms on the magnetocaloric effect has been evidenced. Besides, the presence of antiphase boundaries linked to superdislocations helps to understand the spin-glass behavior at low temperatures in martensite. Finally, the particles in the deformed state were introduced in a photosensitive polymer. The mechanical damping associated to the Martensitic Transformation (MT) of the particles is clearly distinguished in the produced composite, which could be interesting for the development of magnetically-tunable mechanical dampers.

Tailoring surface morphology of heterostructured iron-based Fenton catalyst for highly improved catalytic activity

Due to the great limitation of glass forming ability, precisely controlling the chemical compositions of metallic glasses (MGs) still dramatically inhibits their widespread applications in wastewater remediation. Here, heterostructured catalysts were exploited by rapid annealing of Fe-based MGs and subsequent ball milling (BM) as advanced alternatives for amorphous counterparts in Fenton-like process. It was found that the surface characteristics tailored by ball milling enable more chemically active sites due to its enlarged specific surface area, surface defects and nanosized amorphous oxide layer that significantly enhance surface-catalyzed reaction in Fenton-like process. On the other hand, high-temperature annealing induced grain growth and electrochemical potential difference induced effect of galvanic cells in multiple crystalline phases (e.g. α-Fe (Si), Fe2B and Fe3Si) further provide an important contribution to high efficiency of electron transfer in heterostructured catalysts. Since the multiphase heterostructure is easily formed by a high-temperature annealing of MGs/amorphous-crystalline composite alloys, this work aims to provide an advanced alternative of MG catalyst without the elemental limitation of glass forming ability for wastewater remediation.

Selectively modified nanostructured fluorcanasite glass-ceramic with enhanced micromechanical properties

We report for the first time, synthesis of mesoporous nano-fluorcanasite (n-FC) glass-ceramic from selective glass melting composition using controlled heat treatment and subsequent ball milling. Particle size analysis along with FE-SEM studies confirmed successful synthesis of n-FC particulates with interpenetrating lath like microstructure. XRD study established presence of fluorcanasite, frankamenite, fluorapatite, and xonotlite phases. Pore volume analysis and characteristic adsorption/desorption isotherms of n-FC particulates revealed mesoporous nature with pore diameters in the range of 3 to 15 nm. Interestingly, TEM studies also indicated polycrystalline and mesoporous nature of n-FC particulates and the corresponding ‘d’-spacing values were in good agreement with XRD result. FT-IR spectroscopy further indicated presence of characteristic bands at defined peak positions and crystalline nature of n-FC. Finally, nanoindentation studies indicated enhanced mechanical performance of synthesised n-FC. Overall, our study has established a successful route to synthesise mesoporous nano-fluorcanasite, with favouring microstructure for potential use as bioactive reinforcement.

Microstructure and mechanical properties of graphene-reinforced copper matrix composites prepared by in-situ CVD, ball-milling, and spark plasma sintering

Abstract Graphene-reinforced copper matrix composites were fabricated by in-situ chemical vapor deposition (CVD), ball-milling, and spark plasma sintering (SPS). The effects of different space structures of the graphene/copper powders imparted by ball-milling on the microstructure and mechanical properties of the composites were investigated. It was found that the in-situ CVD process gave complete coating structures of the graphene/copper powders, while subsequent ball-milling damaged the coating structure by breaking the graphene film into pieces on the copper surface. Compared to pure copper, the yield strength and tensile strength of the graphene copper matrix composites were improved by 136.6 and 16.7%, respectively, while its elongation was maintained at 35.2%. In the absence of ball-milling, the composite showed a lower tensile strength and poor electrical conductivity, with an elongation of merely 5.5%. This difference in mechanical properties originates from the different bonding behaviors between the graphene/copper powders. More specifically, weak mechanical interlocking dominates for the composite powders with the coating structure, while strong metallurgical bonding is achieved for the composite powders with uncoating structures. The strengthening mechanisms of graphene were attributed to thermal mismatch, grain refinement, load transfer, and Orowan strengthening.

Enhanced figure of merit in La0.95Sr0.05CoO3/Ag nanocomposites

In this work, we present an experimental study of the influence of silver nanoparticles (AgNPs) addition over the thermoelectric properties of La0.95Sr0.05CoO3 (LSCO) in order to improve its thermoelectric efficiency. For this aim, ceramic samples of LSCO were obtained by solid-state reaction (SSR) and subsequent ball milling in order to reduce their grain size. Then, nano- and submicrometric LSCO/Ag composites were prepared for different Ag volume fractions and by using different sintering temperatures. We have evaluated the thermoelectric efficiency by means of the dimensionless figure of merit, ZT. The results do not follow a clear trend but confirm that the AgNPs addition enhances noteworthy the ZT value of La0.95Sr0.05CoO3. Therefore, it is concluded the validity of the nanocomposite approach on thermoelectric oxides to improve their thermoelectric efficiency.

Effect of particle size on phase transitions of positive active materials made from novel leady oxide during soaking process and its influence on lead-acid battery capacity

Abstract Novel leady oxides with different particle sizes are prepared via pyrolysis of lead citrate in rotary kiln and subsequent ball-milling. The mechanism of how particle size influences the phase transition route of novel leady oxides during soaking process is investigated. PbO with larger particle size (D50 diameter = 22.4 μm) is converted to 3PbO∙PbSO4, and 3PbO∙PbSO4 is then partially transformed to PbO∙PbSO4 while PbO∙PbSO4 are gradually converted to PbSO4. PbO with smaller particle size (D50 diameter = 8.3 μm) is directly converted to PbSO4, and 3PbO∙PbSO4 is partially transformed to PbO∙PbSO4. Phase compositions after the soaking process determine the PbO2 content in positives plates because PbO2 is the oxidation product of PbSO4 in the sequent formation process. Particle size of leady oxides determines the initial capacity of testing cells through affecting the soaking process and a linear correlation between the initial capacity and PbO2 content in positive plates is obtained (R2 = 0.78). Therefore, leady oxides with larger particle size requires higher sulfuric acid density (1.045 g cm−3) to achieve an optimized initial capacity (2.17 Ah), while a lower sulfuric density (1.015 g cm−3) is recommended for small particle leady oxides to achieve an optimized capacity of 2.58 Ah.

Synthesis and electromagnetic wave absorption properties of FeCoNi(Si0.6Al0.2B0.2) high-entropy nanocrystalline alloy powders

FeCoNi(Si0.6Al0.2B0.2) high entropy alloy powders with flaky shapes of 14.7–17.6 μm in mean particle size and 8.2–14.9 in aspect ratio have been prepared by melt-spun and subsequent ball-milling for 10–50 h. The powders possess a mixing structure of BCC nanocrystalline and amorphous phases with average grain sizes of 6–20 nm. The powders exhibit soft magnetic characteristic with saturation magnetization of 78.6–88.1 emu/g. The powders/paraffin (mass ratio = 3:2) composites have high permeability, matchable permittivity, and excellent electromagnetic wave absorption properties in X- and Ku-bands. The composites with thicknesses of 1.2−2.0 mm possess minimum reflection losses (RL) of -38.1 to -44.1 dB with effective absorption bandwidths (RL<10 dB) of 2.5−3.8 GHz.