Powder Mixtures Research Articles

Complex-shaped titanium components fabricated via metal injection molding using hydride-dehydride titanium powder

Metal injection molding (MIM) is a net-shape manufacturing method that lessens the costs of production and increases the affordability of titanium goods. A range of CP-Ti specimens was prepared to confirm the primary manufacturing parameters for titanium metal injection molding utilizing affordable hydride-dehydride (HDH) powders. Mixture of powder and polyformaldehyde-based binder was injection molded, debonded, and then sintered. The optimum powder loading is 55 vol%. The ideal conditions of catalytic debinding were attained by placing the specimens in the catalytic debinding system at 120 °C temperature. Samples with minimal deformation and low impurity content were obtained when thermal debinding was carried out at a modest heating rate of 1.0 K/min and a holding time of 1.5 h. All the sintered samples have a similar microstructure, that is, lamellar α + β structure. The sample exhibits a strength of 739 MPa and an elongation of 6.1 % at the optimum sintering conditions (sintering at 1250 °C for 2 h). The samples prepared by MIM have excellent wear resistance. This process provided a straightforward and cost-effective means of producing complex-shaped titanium components from HDH Ti powder.

Microstructure and coupling mechanisms in MnBi–FeSiB nanocomposites obtained by spark plasma sintering

Fabrication and extensive characterization of hard-soft nanocomposites composed of hard magnetic low-temperature phase LTP-MnBi and amorphous Fe70Si10B20 soft magnetic phase for bulk magnets are reported. Samples with compositions Mn55Bi45 + x⋅(Fe70Si10B20) (x = 0, 3, 5, 10, 20 wt.%) were prepared by spark plasma sintering of powder mixtures. Characterization has been performed by X-ray diffraction, scanning and transmission electron microscopy, magnetometry and 57Fe Mӧssbauer spectroscopy. It was shown that samples contain crystallized and nanometric LTP-MnBi phases with various elemental compositions depending on the degree of Bi clustering. Complex correlations between starting compositions, processes during fabrication, and functional magnetic characteristics were observed. Unexpected special situations of the relation between microstructure and magnetic coupling mechanisms are discovered. Exchange spring effects of different strengths occur, being very sensitive to morpho-structural and compositional features, which in turn are controlled by processing conditions. An in-depth analysis of related microscopic characteristics is provided. Results of this work suggest that fabrication by powder metallurgy routes, such as spark plasma sintering of hard and soft magnetic powder mixtures, of MnBi-based composites with exchange spring phenomena have a high potential in designing and optimization of suitable materials with tunable magnetic properties towards rare-earth–free permanent magnet applications.

Selective laser sintering and spark plasma sintering of (Zr,Nb,Ta,Ti,W)C compositionally complex carbide ceramics

AbstractTwo advanced manufacturing processes, spark plasma sintering (SPS) and selective laser sintering (SLS), have been developed for synthesis of (Zr,Nb,Ta,Ti,W)C compositionally complex carbide (CCC) via reactive sintering of a powder mixture of constitute monocarbides. X‐ray diffraction analysis confirmed that the single‐phase CCC can be formed by both SPS and SLS. While a homogenous microstructure with uniform metal element distributions was developed during SPS, three‐layer microstructures with a thin TiC‐rich layer and two TaC‐rich layers along with a TiO2‐rich surface layer containing W nanoparticles were formed during SLS. In addition, cellular structures with W, Zr, and Ti element segregation and dislocations on cell boundaries were observed in the SLS‐CCC sample, indicating the effect of nonequilibrium conditions on microstructure formation during laser melting followed by rapid cooling and solidification process. Compared to the SPS‐CCC sample, the SLS‐CCC showed enhanced hardness and reduced thermal conductivity, which may be related to their unique cellular structures.

Combustion synthesis of TiC- high entropy alloy CoCrFeNiMn composites from granular mixtures

The advantage of combustion synthesis is the ability to produce composites from powders in a single technological step, using the heat of an exothermic reaction, in a fast and energy-efficient manner. Ceramic-metal composites TiC–High-Entropy Alloy (HEA) CoCrFeNiMn were fabricated by combustion synthesis from granular mixtures. The content of the metal binder components varied from 10 to 30 wt% and the combustion velocity and temperature gradually decreased as the binder content increased. Scaling up synthesis requires clarification of the parametric range for implementing a safe combustion mode. The impurity gas content and the range of safe conductive combustion were determined from known theoretical models and experimental combustion velocities of samples of granules of 0.6 and 1.1 mm size. The main phases of the product were titanium carbide with up to 3 at. % Cr and HEA CrCoFeNiMn with a reduced Mn content compared to the equimolar composition. The content of secondary phases Cr7C3 and carbon did not exceed 5 wt%. The use of granular mixtures solved the problem of significant sintering of exothermic powder mixtures containing metal binder during combustion. After synthesis, the granules retain their size and do not sinter together, making it easy to grind the sample and obtain a TiC-HEA composite powder.

Synthesis of Copper–Nickel and Iron–Nickel Alloys by Hydrogen Reduction of Mixtures of Metal Oxide Powders

AbstractThe vast majority of metals production is based on the use of carbon as a reductant and/or a heating fuel. This results in a large amount of carbon dioxide emissions and should be minimized to limit global warming. In this study, powders of copper–nickel alloy and iron–nickel of varying compositions were produced in a single step by reduction of mixtures of Cu2O-NiO and Fe2O3-NiO powders, respectively, using hydrogen as a reductant. Reduction was performed in a horizontal tube furnace at 700 °C for 45 min. All processing was in the solid state and alloys were produced directly from elemental metal oxides. Exhaust gases were analyzed using a gas analyzer to measure the water content to track the progress of the reduction. Reduction was declared complete when the water content in exhaust gases matched the level before hydrogen was introduced. Both copper–nickel and iron–nickel alloys were produced successfully. X-ray diffractometry confirmed the absence of oxides in the product and the presence of solid phases in agreement with the relevant binary phase diagram. Energy-dispersive X-ray spectroscopy in a scanning electron microscope showed macroscopic homogeneity at the expected composition for each powder mixture directly after reduction, with microscopic fluctuations of the order of several mass percent, within the limits of fluctuations observed following typical casting processes. These promising results warrant further investigation to apply this concept to more chemistries and to scale up the process to a pilot scale. Graphical Abstract

The effect of TiSi2 healing improver in self-healing ability of ceramics

A method to enhance the temperature range in which continuous self-healing fiber-reinforced ceramics (shFRCs) can self-heal is proposed to obtain a new high-temperature structural material. The effect of TiSi2 oxidation on self-healing was investigated using SiC, a typical self-healing agent, and TiSi2, which oxidizes at a lower temperature than SiC. Mixtures of SiC and TiSi2 powders were prepared by wet-mixing, and changes in their high-temperature oxidation behavior were investigated using thermogravimetry/differential thermal analysis. The oxidation of TiSi2 at 1000 °C enhanced the oxidation rate of SiC by 2–3 times. A shFRC consisting of an Al2O3 matrix, an interface layer of SiC and TiSi2, and Al2O3 fiber bundles was fabricated by slurrying and filament-winding. The strength recovery of the shFRC following three-point bending was investigated, and results indicated that the prepared material recovered 50 times faster than conventional shFRCs at 1000 °C. The self-healing improver described in this study can promote the oxidation of self-healing agents via its reaction heat. Thus, this improver may be applied as a practical component of self-healing materials.

Exploration of a new AlCoCrNiNb high-entropy alloy: in situ alloying of a CoCrMo, M247, and Nb powder mixture via laser powder bed fusion

AbstractHigh-entropy alloys (HEAs) have compelling advantages, such as high strength and corrosion resistance, but they remain underexplored owing to the limited availability of certain prealloyed and elemental powders. In this study, an AlCoCrNiNb HEA was fabricated in situ via laser powder bed fusion (LPBF) using a powder mixture of commercial CoCrMo, Mar M247, and Nb elemental powders. The powder mixture was blended for 24 h using a horizontal blending machine, to obtain similar chemical compositions in the middle and top layers of the blended powder. However, local Nb aggregation was observed in the bottom layer owing to the particle-size effect. X-ray diffraction and chemical composition analyses revealed that the in situ alloyed AlCoCrNiNb HEA specimen obtained via LPBF was a homogeneous solid solution with a face-centered cubic structure. HEA exhibits a fine-grained morphology, and its maximum microhardness is approximately 970 HV. These characteristics are typical of rapid solidification and sluggish diffusion. These results underscore the effectiveness of using commercial prealloyed and elemental powders for fabricating AlCoCrNiNb HEAs through LPBF-based in situ alloying, thus advancing the development of HEAs. Thermodynamic calculations were performed to support these outcomes.

Influence of Processing Parameters on Laser-Assisted Reactive Sintering of a Mixture of Ni and Ti Powders

Additive manufacturing (AM) plays a crucial role in the development of NiTi alloys, enabling the creation of complex and customized structures while optimizing properties for various biomedical and industrial applications. The aim of this paper was to investigate the influence of laser scanning speed on laser-assisted reactive sintering of a mixture of No and Ti powders. The samples were sintered at two different beam speeds, 4 and 5 4 mm/s and their morphological and microstructural characteristics were investigated. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction (XRD) analyses revealed the presence of intermetallic compounds rich in Ni and Ti for both scanning speeds; however, the scanning speed of 5 mm/s produced a microstructure with greater porosity, leading to a sintered body with poorer consolidation. Thus, employing a slower beam scanning of 4 mm/s seems to be a better alternative in the laser-assisted reactive sintering of NiTi alloys.

Characterization of the microstructural, magnetic, and thermal behaviors of boron-doped Fe–Co–Ni alloys produced via mechanical alloying

FeCoNi alloys, both doped and undoped, were synthesized into nanocrystalline forms using a high-energy mechanical milling technique. The study used the x-ray diffraction technique to examine the microstructure characteristics of powder materials. The identified patterns were examined using Maud software. It was found that mechanical alloying produced solid solutions with BCC and FCC structures and crystallite sizes in the range of 25 nm after 100h of milling. The BCC-Fe(Co,Ni,B) and orthorhombic-Fe3B phases were refined for the alloy doped with amorphous boron, while only the bcc-Fe(Co,Ni,B) phase was identified for the alloy doped with crystalline boron. Meanwhile, the FeCoNi alloy revealed a mixture of FCC-Co and BCC-FeCoNi phases. This sample has a soft ferromagnetic behavior, whereas the doped ones have hard ferromagnetic behaviors. The squareness ratios (Mr/Ms) are typically low. The microstructural variations were associated with magnetic characteristics. The thermal stability of the alloyed powder mixtures was investigated by the DSC technique from 25 to 700 °C for 2h. The alloyed samples were first annealed at selected temperatures and then analyzed using x-ray diffraction. The obtained x-ray diffraction results proved that at temperatures below 230 °C, the initial heavy deformed structure’s structural relaxation followed by the recrystallization of the fcc-Co phase and, at higher temperatures, the recrystallization of new phases, such as α-FeCo, fcc-FeNi, fcc-Ni3Fe, and borides of the (FeNi)23B6, -(FeCo)23B6 types. The stability of the crystalline phases that are formed and their magnetic characteristics can be regulated through a carefully calibrated annealing process.

Supercritical hydrothermal synthesis of ultra-fine Cu powders

ABSTRACT Ultra-fine Cu powders were synthesized using supercritical water as a reaction medium and formic acid as a reducing agent. The effects of reducing agent, reaction temperature, and complexing agent on the phase constituents, particle size distributions and morphology of the synthesized ultra-fine Cu powders were investigated. A complex mixture of Cu2O and Cu powders formed by pure supercritical water while high purity homogeneous ultra-fine Cu powders can be synthesized by supercritical water with formic acid as a reducing agent. Moreover, fine tuning of particle size and morphology can be realized by the addition of Ethylenediamine tetraacetic acid (EDTA). The modification mechanism of EDTA on the surfaces of ultra-fine Cu powders was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. EDTA adsorbed on the surfaces of nanoparticles by the dehydration reaction of carboxyl groups in the molecule of EDTA and hydroxyl groups on surfaces of copper nanoparticles (CuOH).

Design and Characterization of a Continuous Melt Milling Process Tailoring Submicron Drug Particles

Solid crystalline suspensions (SCSs) containing submicron particles were introduced as a competitive solution to increase dissolution rates and the bioavailability of poorly water-soluble drugs. In an SCS, poorly water-soluble drug crystals are finely dispersed in a hydrophilic matrix. Lately, melt milling as an adapted wet milling process at elevated temperatures has been introduced as a suitable batch manufacturing process for such a formulation. In this work, the transfer from batch operation to a two-step continuous process is demonstrated to highlight the potential of this technology as an alternative to other dissolution-enhancing methods. In the first step, a powder mixture of a model drug (griseofulvin) and a carrier (xylitol) is fed to an extruder, where a uniform suspension is obtained. In the second step, the suspension is transferred to a custom-built annular gap mill, where comminution down to the submicron region takes place. The prototype’s design was based on batch grinding results and a narrow residence time distribution, intended to deliver large quantities of submicron particles in the SCS. The throughput of the mill was found to be limited by grinding media compression. By inclining the mill at an angle, the grinding media position was manipulated, such that compression was avoided. Different states of the grinding media in the grinding chamber were identified under surrogate conditions. This strategy allows the maintenance of an energy-optimized comminution without adaption of the associated process parameters, even at high throughputs. Using this new process, the production of an SCS with 80–90 % submicron particles in a single passthrough was demonstrated.

Design and Characterization of a Continuous Melt Milling Process Tailoring Submicron Drug Particles

Solid crystalline suspensions (SCSs) containing submicron particles were introduced as a competitive solution to increase dissolution rates and the bioavailability of poorly water-soluble drugs. In an SCS, poorly water-soluble drug crystals are finely dispersed in a hydrophilic matrix. Lately, melt milling as an adapted wet milling process at elevated temperatures has been introduced as a suitable batch manufacturing process for such a formulation. In this work, the transfer from batch operation to a two-step continuous process is demonstrated to highlight the potential of this technology as an alternative to other dissolution-enhancing methods. In the first step, a powder mixture of a model drug (griseofulvin) and a carrier (xylitol) is fed to an extruder, where a uniform suspension is obtained. In the second step, the suspension is transferred to a custom-built annular gap mill, where comminution down to the submicron region takes place. The prototype’s design was based on batch grinding results and a narrow residence time distribution, intended to deliver large quantities of submicron particles in the SCS. The throughput of the mill was found to be limited by grinding media compression. By inclining the mill at an angle, the grinding media position was manipulated, such that compression was avoided. Different states of the grinding media in the grinding chamber were identified under surrogate conditions. This strategy allows the maintenance of an energy-optimized comminution without adaption of the associated process parameters, even at high throughputs. Using this new process, the production of an SCS with 80–90 % submicron particles in a single passthrough was demonstrated.

Investigation on characteristic of vanadium trioxide insulation mixed with metal powder for rare-earth barium copper oxide coils

This study examined the turn-to-turn contact resistance (R ct) between rare-earth barium copper oxide (REBCO) tapes and layers of vanadium trioxide (V2O3) and V2O3 mixed with metal powder mixture. V2O3 in single crystal structure was electrically characterised to exhibit resistivity with negative temperature dependence, allowing the turn-to-turn insulation to self-regulate the current bypass between REBCO tapes. To facilitate effective quench protection of V2O3-insulated REBCO magnets above the metal-insulator transition temperature (T rt), R ct must be further reduced to a level similar to those of non- and metal as insulated (NI and MI) REBCO magnets. Thus, we explored the mixing of conductive metal powders such as molybdenum (Mo) with V2O3 paste and investigated the transition properties of R ct. The resistance versus temperature characteristics, microscopic morphologies of the V2O3 layers, and thermal conductivity (k v) were appropriately assessed to determine the effects of mixing the metal powder with V2O3. The R ct of virgin V2O3 exhibited variations of 107–105 μΩ cm2 under 77–293 K. As the mixing concentration of the metal powder was increased, the reduction magnitude on R ct increased for > T rt (approximately 150 K). Furthermore, the transition slope became gentler for a wider temperature range of < T rt. For metal powder concentrations exceeding 50 wt%, R ct decreased by approximately 2 orders of magnitude (∼103 μΩ cm2) for > 150 K compared with that for virgin V2O3 paste. Moreover, compared to that of pure V2O3, k v demonstrated a remarkable increase of approximately 352% at 91 K for Mo powder mixed at a concentration of 60 wt%. The improved electrical and thermal properties of the V2O3 insulation layer owing to the mixing of metal powders can help REBCO magnets operate in an insulated state under normal conditions and effectively convert to a non-insulated state under quenching.

Fabrication and Evaluation of Mechanical and Tribological Properties of Al-Foam Produced by Powder Metallurgy Route

In the present study, the production of aluminum foam was carried out using the powder metallurgy technique, specifically employing the sintering – dissolution process (SDP). The SDP method, which constitutes a sequential series of four well-defined steps, was employed to achieve the desired foam structure and properties. These steps involved carefully controlling the parameters and conditions throughout the process to ensure successful foam formation. Aluminum powder with a particle size of (1.99 μm) as a raw material was mixed with NaCl with a particle size between (150-425μm) used as a space holder at different ratio (25, 35, 45and 55 wt. %.). Obtained Al-foam with 45% NaCl demonstrated the most optimal structure. Some additives (Mg) added to the powder mixture, it was found that the mechanical and the tribological properties of the produced foam were improved. The introduction of metal’s micro-particles led to a notable enhancement in both compressive stress and micro-hardness, the compressive stress increased substantially from 15.2 MPa to 56.5 MPa for the foam containing 45% NaCl and 45% NaCl + Add., respectively. While the micro-hardness exhibited a noteworthy increase from 51.5 HV to 62.1 HV. Results also showed important reduction in the wear rate from (0.00000155 g/cm) to (0.00000079 g/cm) for the Al-samples of (45% NaCl) and (45% NaCl+ Additive) respectively, the lowest value recorded for the coefficient of friction was (0.15) for (Al-Foam with 45% NaCl + Additive) compare to (0.19) and (0.21) for (Al-foam with 45% NaCl) and (pure Al) respectively at 10 N applied load and 800 rpm.

Stress Release–Induced Suction in Unsaturated MX80 Bentonite Pellet and Powder Mixtures

Stress Release–Induced Suction in Unsaturated MX80 Bentonite Pellet and Powder Mixtures

The Influence of B4C Content on the Pore Structure of Reaction-Synthesized Porous Ti3AlC2-TiB2 Composite Ceramics

Using a mixture of TiH2, Al, B4C, and graphite powders with a molar ratio of 3+2m/1.2/m/2-m (where m ranges from 0 to 0.25, with increments of 0.05), porous Ti3AlC2-TiB2 composite ceramics were successfully synthesized through activated reaction sintering. The effect of B4C content on the phase composition, volumetric expansion, microstructure, and pore structure parameters (including pore size, porosity, and permeability) was systematically studied. When the molar ratio of B4C was less than 0.1, the volumetric expansion rate, average pore size, and permeability increased with the addition of B4C, reaching maximum values of -5.46%, 2.23μm, and 92.4m3·m-2·10KPa-1·h-1, respectively. Conversely, when the B4C molar ratio exceeded 0.1, the parameters related to the pore structure of the porous Ti3AlC2-TiB2 composite ceramics decreased, with minimum values of -10.40%, 1.46μm, and 68m3·m-2·10KPa-1·h-1, respectively. In addition, the pore formation mechanism of the porous Ti3AlC2-TiB2 composite ceramics was systematically explored. The revolution tendency of pores is related to the decomposition of TiH2, Kirkendall partial diffusion, diffusion between B and C, and the transition process of the final phase Ti3AlC2-TiB2. This research work could provide a reference for the preparation of the MAX phase composite porous materials.

Photoluminescence of CaGa2S4: Nd, Yb compound at room temperature

In this paper, CaGa2S4:3%Nd,5%Yb; CaGa2S4:5%Yb; CaGa2S4:3%Nd compounds were synthesized, and their photoluminescence (PL) spectra, PL excitation (PLE) spectra and PL decay properties were studied at room temperature under one-photon and multi-photon excitation in a wide range of excitation intensities. The synthesis of the CaGa2S4 compound was carried out by a solid-phase reaction of a stoichiometric mixture of CaS and Ga2S3 powders in a quartz ampoule. Yb and Nd doping was carried out during the synthesis process using YbF3 and NdF3. PLE spectra were studied in the wavelength range from 250 to 850 nm, and PL spectra in the range of 400 - 1500 nm. It has been shown that after introducing Yb3+ ions into thiogallate crystals with Nd3+ ions, a new band near 488 nm is formed and the PL intensity increases by 1-2 orders of magnitude. The anti-Stokes PL spectra of CaGa2S4: Nd, Yb crystals in the visible region of the spectrum (400–700 nm) were studied when excited by continuous wave laser radiation with a wavelength of 975 nm. The kinetics of PL decay of all types of compounds at different wavelengths of single- and multi-photon excitation were determined. Depending on the PLE conditions, wavelength and intensity of the exciting radiation, monoexponential and non-monoexponential decay kinetics were observed with decay times in the range of 20 – 90 μs. Possible mechanisms of PLE and PL of CaGa2S4 crystals doped with neodymium and ytterbium ions are discussed.

A comparison of multivariate curve resolution with endmember extraction methods in hyperspectral Raman imaging

Hyperspectral Raman imaging not only offers spectroscopic fingerprints but also reveals morphological information such as spatial distributions in an analytical sample. However, the spectrum-per-pixel nature of hyperspectral imaging (HSI) results in a vast amount of data. Furthermore, HSI often requires pre- and post-processing steps to extract valuable chemical information. To derive pure spectral signatures and concentration abundance maps of the active spectroscopic compounds, both endmember extraction (EX) and Multivariate Curve Resolution (MCR) techniques are widely employed. The objective of this study is to carry out a systematic investigation based on Raman mapping datasets to highlight the similarities and differences between these two approaches in retrieving pure variables, and ultimately provide guidelines for pure variable extraction. Numerical simulations and Raman mapping experiments on a mixture of pharmaceutical powders and on a layered plastic foil sample were conducted to underscore the distinctions between MCR and EX algorithms (in particular Vertex Component Analysis, VCA) and their outputs. Both methods were found to perform well if the dataset contains pure pixels for each of the individual components. However, in cases where such pure pixels do not exist, only MCR was found to be capable of extracting the pure component spectra.

Exploring co-processing strategies for multi-material spark plasma sintering of pure Cu with AlSi10Mg by master sintering curves

Manufacturing complex multi-material metallic components without assembly operations is currently being explored using novel additive manufacturing techniques. For materials combinations that are difficult to process via melting-based processes, multi-material spark plasma sintering (SPS) appears as a promising alternative. However, due to different sintering kinetics, materials with very different melting points might have to be co-sintered at non-optimal conditions. In this work, the potential to improve the co-sinterability of dissimilar materials, namely pure copper and AlSi10Mg, is evaluated by altering the sintering kinetics of copper using different particle size distributions (PSD). Using the master sintering curve (MSC) approach, the densification behaviour of spherical pure copper powder during SPS is evaluated systematically to study the influence of PSD, uniaxial applied pressure, and isothermal holding temperature. An intermediate-sized monomodal and close-to-optimal bimodal PSD are compared for processing at lower sintering temperatures. It was observed that, compared to an intermediate monomodal PSD, a near-optimal bimodal powder mixture yields fully dense Cu–AlSi10Mg components at lower temperature and shorter process times. Therefore, the use of a bimodal mixture enables multi-material sintering, offers energy and cost savings to produce multi-material components, and improves compatibility between materials with very different melting points.

The effect of pressure and temperature on the properties of 88 W-10Ni-2Mn tungsten heavy alloy produced by cold press method

This research explored the impact of pressure and temperature to determine the optimal conditions for producing an 88 W-10Ni-2Mn tungsten heavy alloy (WHA) suitable for industrial purposes. To achieve this objective, tungsten, nickel, and manganese powders with predetermined ratios underwent wet milling in a two-step process. Subsequently, the powder mixture underwent compression at two pressures, namely 200 MPa and 250 MPa, employing the cold press method. The compressed mixture was then subjected to sintering in a tubular furnace at temperatures of 1200 °C, 1250 °C, 1350 °C, and 1400 °C. Microstructural characterization was conducted using optical and scanning electron microscopes (SEM). The findings indicated that increasing both pressure and temperature resulted in an enhancement of the sintering density in the samples. The optimum value was achieved at 1400 °C and 250 MPa, reaching 90.11 g/cm3. Furthermore, in the quenching sintering process, the carburization of 88 W-10Ni-2Mn WHA contributed to an increase in the micro hardness of the samples, reaching a maximum of 529 HV. The hardness exhibited an increase from 355 HV to 529 HV with a temperature rise from 1200 °C to 1250 °C. However, it decreased from 377 HV to 352 HV when the temperature increased from 1350 °C to 1400 °C. The increase of sintering temperature also led to slightly increases the continuity of tungsten‑tungsten due to the growth of tungsten particles. By increasing the temperature from 1350 °C to 1400 °C, ductile fracture was observed in WHA.