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Recent Advances in Welding Processes for High-Entropy Alloys: A Comprehensive Review
(2026-01-01)
Li, Min
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Pimsarn, Monsak
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Chuwattanakul, Varesa
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Eiamsa-Ard, Smith
High-Entropy Alloys (HEAs) have gained attention for their exceptional mechanical properties, corrosion resistance, and unique microstructure. However, welding HEAs remains challenging, attributed to intricate microstructures, inadequate thermal conductivity, and elevated melting points. This review systematically summarizes recent advances in metal welding of HEAs with both similar and dissimilar alloys, including stainless steel, titanium alloys, aluminum alloys, and nickel-based alloys. Welding techniques, including Gas Metal Arc Welding (GMAW), Laser Welding (LW), Electron Beam Welding (EBW), and Gas Tungsten Arc Welding (GTAW) are critically compared in terms of joint microstructure, mechanical performance, and corrosion behavior. The influence of filler composition, heat treatment, and process parameters on weld quality are discussed. Key challenges, including microstructure evolution under complex service conditions and controlling brittle intermetallic phases, are identified. Finally, potential research directions and application prospects of HEA welding in advanced manufacturing are outlined.
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High-Temperature Deformation and Subsequent Static Recrystallization Behavior of Ultra-Low Stacking-Fault Energy Cu-Zn-Si Alloys
(2026-01-01)
Miura, Hiromi
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Kasuya, Sanshiro
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Oba, Yojiro
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Okada, Takuya
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Watanabe, Chihiro
Behaviors of high-temperature deformation followed by annealing and static recrystallization (SRX) in Cu-Zn-Si alloys with ultra-low stacking-fault energy (SFE) were investigated. The peak stress, steady-state flow stress and grain size during high-temperature deformation appeared to decrease with decreasing SFE, which would suggest easier occurrence of dynamic recrystallization (DRX) with decreasing SFE. Nevertheless, with increasing initial grain size, onset of DRX was much delayed even at higher temperatures and lower strain rates. SRX started after annealing for rather long periods of time contrary to the expectation that SRX should be stimulated because of meta-DRX. New grains evolved by DRX and SRX contained quite high density of annealing twins, showing DRX and SRX mechanisms induced by annealing twin formation during grain-boundary migration. [doi:10.2320/matertrans.MT-D2025015]
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A New Technique for Brazing Porous Copper to Copper Substrate Using CuNiSnP Amorphous Filler Metal
(2025-11-01)
Mookam, Niwat
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Jattakul, Prajak
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Ariga, Tadashi
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Kanlayasiri, Kannachai
Furnace brazing is a common method for bonding porous metal to a substrate. However, it typically involves lengthy brazing times. This research introduces a novel rapid brazing technique to join porous copper to copper substrates. Using CuNiSnP amorphous filler metal, porous copper specimens were brazed under varying currents (250-1000 A) and times (900-1100 ms). Results showed successful joining without macroscopic deformation of the porous copper, and the brazing times were significantly shorter than those of traditional methods. Microstructural analysis revealed primary alpha, primary beta, and eutectic structures in the joint, all of which were influenced by brazing current and time. Adjusting the brazing conditions altered the morphology of the primary alpha structure, ranging from equiaxed to columnar dendrites, which in turn affected the joint's mechanical properties. The proposed technique offers an efficient method to manipulate joint microstructures for bonding porous copper to copper substrates, potentially improving manufacturing efficiency in industries such as heat exchangers or catalytic converters.
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Modulating Fish Gelatin Gelling Properties Through Furcellaran Addition: A Structural and Physicochemical Analysis
(2025-06-01)
Petcharat, Tanyamon
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Chaijan, Manat
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Indriani, Sylvia
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Pongsetkul, Jaksuma
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Karnjanapratum, Supatra
Fish gelatin (FG) is a promising alternative to mammalian gelatin but is limited by poor gelling ability, low gel strength, and inability to set at room temperature. This study evaluated the effects of furcellaran (FUR), a gelling agent, on the structural and physicochemical properties of FG gels at different substitution levels (25–100%). The addition of 25% FUR improved gel strength and hardness. However, higher FUR levels (>50%) led to reduced springiness and increased syneresis. Intermolecular force measurements revealed that ionic and hydrogen bonds were crucial in the FG/FUR gel system, with higher levels of FUR promoting stronger ionic and hydrogen bonding. Color changes were observed with decreased L* and increased b* and ∆E* values as FUR levels rose. Gelling and melting points also increased proportionally with FUR content. Microstructural analysis showed denser gel networks with smaller gaps upon FUR incorporation. SAXS analysis confirmed enhanced structural conformation with higher FUR levels. An appropriate level of FUR added (25%) could therefore improve gelling properties via increasing gel strength and gelling temperature without negative effects on springiness and syneresis of resulting gel.
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Effect of foam-mat drying conditions on drying rate and anthocyanin content in purple sweet potato powder
(2025-01-01)
Nguyen, Chi Dung
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Hong, Van Hao
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Tran, Ngoc Giau
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Nguyen, Minh Thuy
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Ngo, Van Tai
The study aimed to optimise foam-mat drying parameters for producing purple-fleshed sweet potato (PFSP) powder. Egg albumin (EA) (5–15%), xanthan gum (XG) (0.1–0.5%), and drying temperature (50–70 °C) were used as independent variables for optimisation via Response Surface Methodology with a Box-Behnken design. The response variables (drying rate and anthocyanin content) were assessed by 18 treatments, which included 6 central points. The analysis of variance showed a high coefficient of determination (> 88%) between predicted and experimental values across all models. Optimal foam-mat drying conditions were 11.02% EA, 0.34% XG, and 65.1 °C to achieve the highest drying rate (2.49 g water.g dry matter–1.min–1) and anthocyanin content (1.01 mg.g–1). After 3.5 h of drying at 65.1 °C, the foam-mat dried PFSP showed a low moisture content (4.35%) and water activity (0.29). Its water solubility index, water absorption index, rehydration ratio, total polyphenols, and antioxidant activity were determined to be 56.49%, 3.55%, 3.82, 3.66 ± 0.06 mg GAE.g–1, and 58.49 ± 0.88%, respectively. Under these conditions, the powder maintained its natural beautiful and characteristic purple colour. The microstructure of the foam-mat dried PFSP powder (via SEM images) was also observed.
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Mg Alloy Rod Strengthened by Combined Processes of Deformation-Restricted Forging and Extrusion
(2024-01-01)
Miura, H.
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Oba, Y.
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Watanabe, C.
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Benjanarasuth, T.
A new method for strengthening Mg alloy rod is proposed. AZ80Mg alloy rods were forged along the longitudinal axis (LA) at extremely high pressures beyond fracture stress under a condition where plastic deformation was eliminated in a die, i.e., deformation-restricted forging (DRFing), followed by cold extrusion. Although the ultimate tensile strength (UTS) and hardness were gradually raised with DRFing stress, the yield strength (YS) was lowered by sharp basal texture evolution on the plane normal to the LA and tensile axis. However, the extrusion after DRFing drastically changed the texture to (0001) LA, causing a large increase in YS. Consequently, a superior balance of mechanical properties: YS of 376 MPa, UTS of 417 MPa, and ductility of 10%, could be achieved after the combined processes of DRFing and extrusion.
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Enhancement of the Dielectric and Energy Storage Properties of Lead-Free BNSLT Ceramics by Zr4+ Substitution into B-Sites
(2023-01-01)
Luangpangai, Anupong
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Noiphoowiang, Nachtarika
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Premwichit, Pathit
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Klinbanmor, Metarsit
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Vittayakorn, Naratip
(Bi<inf>0.38</inf>Na<inf>0.30</inf>Sr<inf>0.28</inf>)<inf>0.98</inf>La<inf>0.02</inf>Ti<inf>1-x</inf>Zr<inf>x</inf>O<inf>3</inf> (abbreviated as BNSLT<inf>1-x</inf>Zr<inf>x</inf>, with x = 0 − 0.05) lead free ceramics were fabricated using the solid-state combustion method. The phase structure, microstructure and electrical properties of the ceramics were investigated. The coexistence of the rhombohedral (R) and tetragonal (T) phases was found in all samples. Rietveld refinement confirmed that as x increased from 0 to 0.05, the rhombohedral phase increased from 41 to 60%. A nearly equal R:T phase ratio of 49:51 was obtained for x = 0.01. All ceramics displayed polygonal grain shapes with anisotropic grain growth. The average grain size of the ceramics was in the range of 0.46–0.79 µm. The optimal Zr4+ content resulted in increased grain growth and reduced pores, leading to improved electrical properties. The highest density (5.52 g/cm3), maximum dielectric constant (ε <inf>m</inf> =2156), maximum polarization (P<inf>max</inf>=15.36 µC/cm2) and high energy storage properties (W<inf>total</inf>=0.49 J/cm3, W<inf>rec</inf>=0.45 J/cm3, W<inf>loss</inf>=0.05 J/cm3 and η = 90.54% at 60 kV/cm) were obtained from x = 0.01 caused by a morphotropic phase boundary (MPB) and good morphology.
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Multiferroic Properties of (1-x)BiFeO3-xBaTiO3 Lead-Free Ceramics
(2023-01-01)
Panpho, Phakakorn
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Intrirak, Kumaret
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Vittayakorn, Naratip
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Jantaratana, Pongsakorn
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Bongkarn, Theerachai
Lead-free (1-x)BiFeO<inf>3</inf>-xBaTiO<inf>3</inf> ceramics (abbreviated as BF-xBT), in a composition range of 0.23 ≤ x ≤ 0.33 mol%, were prepared by the conventional solid-state reaction method. The effect of x content on phase structure, microstructure, magnetic and electrical properties of BF-xBT ceramics is also investigated. With the incorporation of x content, the coexistence of rhombohedral and tetragonal phases was observed. Field emission scanning electron microscope (FESEM) micrographs revealed that the average grain size of BF-xBT ceramics first decreased and then increased with adding x content. The fracture surface of samples showed a mode of inter-granular fracture and intra-granular fracture. The ferroelectric properties were enhanced by adding x ≥ 0.29 mol% in the BF-xBT system. The dielectric and magnetic properties were improved with a maximum value are ε<inf>r</inf> = 888,711, M <inf>max</inf> = 0.40 emu/g, M <inf>r</inf> = 0.17 emu/g, and H <inf>c</inf> = 3.7 kOe at x = 0.25 mol%.
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Effect of Na+ Substitution on the Phase, Microstructure, Electrical and Energy Storage Properties of BSBZNT Ceramics Prepared by the Solid-State Combustion Technique
(2023-01-01)
Chongsatan, Wistsarut
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Didpim, Ratirom
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Julphunthong, Phongthorn
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Thatawong, Bhoowadol
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Vittayakorn, Naratip
(Ba<inf>0.704</inf>Sr<inf>0.176</inf>Bi<inf>0.12</inf>)<inf>1-x</inf>Zn<inf>0.08</inf>Nb<inf>0.04</inf>Ti<inf>0.88</inf>O<inf>3</inf>-Na<inf>x</inf> (BSBZNT-xNa) ceramics with x = 0, 0.01, 0.03 and 0.05 mol%, were prepared by the solid-state combustion technique. The samples were calcined and sintered at 950 °C and 1375 °C, respectively, for 2 h. The phase, microstructure, dielectric, ferroelectric and energy storage properties were investigated. The X-ray diffraction patterns of the BSBZNT-xNa powders showed a perovskite phase for all samples. When x increased from 0-0.03, the average particle size increased from 380 to 480 nm, then decreased to 420 nm. All sintered samples showed the coexistence of the orthorhombic and cubic phases. The average grain size was in the range of 2.03 to 1.39 µm. The BSBZNT-0.01Na ceramic exhibited the highest dielectric properties at room temperature (ɛ<inf>r</inf> = 902, tanδ = 0.10), the lowest remanent polarization (P <inf>r</inf> = 0.10 µC/cm2), coercive field (E <inf>c</inf> = 0.43 kV/cm), and the highest energy storage efficiency (η ∼ 94.70%) measured under an electric field of 70 kV/cm.
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Phase Formation, Microstructure and Electric Properties of Vanadium Doped Lead-Free BaTi0.91Sn0.09O3 Ceramics
(2023-01-01)
Pattanakasem, Wiwat
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Charoenthai, Nipaphat
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Vittayakorn, Naratip
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Bongkarn, Theerachai
Lead-free Ba(Ti<inf>0.91</inf>Sn<inf>0.09</inf>)<inf>1-x</inf>V<inf>x</inf>O<inf>3</inf> (BTSV, x = 0, 0.005,0.010, 0.015, and 0.020) ceramics were prepared by the conventional solid-state sintering method with a calcination temperature of 1200 °C for 2 h and a sintering temperature between 1350 °C and 1400 °C for 4 h. The effect of vanadium (V) doping on the phase formation, microstructure and electrical properties of the ceramics was investigated. X-ray diffraction (XRD) measurements revealed that the ceramics with x = 0 and 0.005 had pure perovskite structures with no detectable impurity, while the ceramics with x ≥ 0.010 exhibited perovskite structures and had secondary impurity phases. Coexisting orthorhombic and tetragonal phases were observed and the Rietveld refinement analysis suggested that the tetragonal phase increased with increased V5+ substitution. When x increased from 0 to 0.010, the average grain size increased from 47 to 62 µm and then dropped, while the density (ρ) decreased from 5.98 to 5.64 g/cm3 when x increased. Furthermore, the BTSV ceramics exhibited increased porosity, Curie temperatures (T <inf>C</inf> ∼ 42 °C to 52 °C) and coercive field (E <inf>c</inf>), while the dielectric constant at the Curie temperature (ε<inf>C</inf>) and the remnant polarization (P <inf>r</inf>) of the ceramics decreased (∼18023 to 6110 and ∼7.42 to 4.88 µC/cm2, respectively) when V5+ doping increased.

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