In this study, homogenization followed by solution and aging treatments was applied to Directed Energy Deposition-Arc (DED-Arc) 2319 Al alloy components. The effects of these heat treatments on microstructure evolution, mechanical properties and corrosion resistance were systematically analyzed. A significant number of acicular strengthening phases θ′ (Al2Cu) and θ″ (Al2Cu) were precipitated after heat treatment. As a result, the hardness increased from 73.9 HV0.5 (as-deposited state) to 148.0 HV0.5 in the aged condition, representing an improvement of 100.3

In this paper, a novel interleaved full-bridge LLC (FB LLC) converter with a wide voltage range is proposed. The converter consists of two FB LLC converters with parallel inputs and series outputs. The two converters share identical resonant tank parameters, operate at the same resonant frequency, and are connected via an auxiliary transformer coupled to the opposite full bridge. The output voltage is regulated by adjusting the phase shift angle between the two full bridges. This topology not only extends the voltage gain range but also enhances the soft-switching capability of the lagging bridge leg, thereby mitigating the ZVS failure issue under large phase shift conditions. The working principle and key performance of the proposed converter are analyzed in detail. Finally, a 500 W prototype is built to verify the theoretical analysis.

In view of the problems of poor low-temperature impact toughness and non-uniform weld microstructure in X80 pipeline steel,X80 pipeline steel was welded by pulsed MAG welding with the addition of nano TiO2,and the effect of adding nano TiO2 on the weld microstructure and mechanical properties was investigated by inducing the nucleation of acicular ferrite through the in-situ synthesis of oxide inclusions.The results indicate that the weld microstructure with added nano TiO2 is mainly composed of acicular ferrite(AF),granular bainite(GB),and polygonal ferrite(PF).The Mn-Ti composite oxides induced by nano TiO2 serve as effective nucleation sites,driving AF to nucleate radially and increasing its content.The grain size is refined from 8.97 um to 5.14 um;the proportion of grain boundary angles greater than or equal to 45° increases by 7.5%;the proportion of low KAM values of less than 1 increases.The nucleation of AF promotes an increase in local dislocation density,which leads to higher partial hardness values.The average tensile strength of the weld with added nano TiO2 reaches 722.67 MPa,and the average low-temperature impact absorption energy at-40 ℃ is 82.91 J,which is an increase of 22.32%;the fracture morphology presents ductile fracture characteristics.The above study provides a new method for improving the microstructure and mechanical properties of pipeline steel welds.

Laser cladding is a key technology in advanced manufacturing and remanufacturing. The microstructure and performance of the cladded layers depend critically on molten pool flow dynamics. While core flow mechanisms such as buoyancy and the Marangoni effect have been extensively studied, edge behaviors, particularly the interplay between inhomogeneous melting and flow evolution, remain insufficiently explored. In this study, a distinct accumulation-ejection-dissipation cycle is revealed at the molten pool boundary via advanced flow visualization techniques that integrate deep learning-based particle segmentation with particle image velocimetry (PIV). During the accumulation stage (t = 0 ms), incomplete melting leads to the formation of a solute layer characterized by near-zero velocities (<= 0.02 m s-1 ). The ejection phase (t = 200 ms) occurs via jet-like bursts from unstable weak points, inducing local vortices and a 7-fold surge in velocity standard deviation (from 0.005 to 0.035 m s-1). The dissipation phase (t = 300 ms) follows with energy depletion, causing non-uniform velocity decay. This periodic behavior exhibits a strong correlation with inhomogeneous melting, as evidenced by 45 degrees directional flow and spatiotemporal alignment of velocity peaks with ejection ports. Furthermore, heat input plays a regulatory role in the cycle: a moderate heat input of 33 J mm-2 enhances non-uniform melting, while a critical heat-input threshold of 100 J mm-2 enables synchronous melting, effectively suppressing the accumulation-ejection cycle. These findings highlight the pivotal role of edge dynamics in governing molten pool stability and offer a mechanistic basis for optimizing laser cladding processes. (c) 2026 Society of Manufacturing Engineers (SME). Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Arc directed energy deposition (DED) is an advanced manufacturing technology based on the layer-by-layer deposition. This method enables the fabrication of components with tailored property gradients, such as the "hard outer and soft inner" structure, which is a significant challenge for conventional manufacturing techniques like casting and forging. Here, we successfully prepared Al-Si-Cu components with chemical gradients using bypass a gas metal arc (GMA)-DED system, the solidification process in different gradient regions was also simulated based on the Scheil-Gulliver model, and the effects of changes in elemental concentration on the microstructure and mechanical properties of the alloy are analyzed in detail. Microstructural characterization shows that in the building direction, the obtained composition is in good agreement with the theoretical distribution calculation; mechanical property test results show that the ultimate tensile strength of the surface layer is 250.8 MPa, elongation is 13.6%, while the maximum elongation in the core area can reach 25.7%, showing the characteristics an heterostructure gradient along the building direction. However, pores between layers and transition areas and microcracks formed due to dislocation accumulation limit the material's toughness. The change in phase structured enabled by the developed bypass GMA-DED approach allows for the control and selection of multiple phases including disk-shaped and rod-shaped θ phase and eutectic β-Si, thus allowing to improve the mechanical response of the fabricated material. This bypass GMA-DED method offers distinct advantages in precise composition control and in-situ alloying capabilities, providing a new paradigm for the production of parts with specialized performance requirements.

Laser cleaning technology has great potential for application in cleaning the parts for remanufacturing in scrapped cars. However, the pollutant detachment mechanism from the parts hasn’t been figured out yet, which makes it difficult to choose the appropriate parameters to achieve optimal cleaning. Thus, the laser cleaning mechanism for a remanufactured torque converter housing (with composition of S355) is studied. The results showed that with increasing laser energy density from 4.59 to 50.93 J/cm2, surface sliding, melting, plasma generation, gasification and phase explosion occurred successively on the surface of the torque converter housing, as speculated by SEM observation, high-speed camera observation and finite element simulation. In addition, the cleaning threshold, ablation threshold and damage threshold are determined to be 5.10 J/cm2, 10.32 J/cm2 and 40.74 J/cm2 respectively. This study may shed light on the industrial application of laser cleaning technology in the automotive field.

In this paper, we propose a novel bipolar voltage and current pulse generation converter (BVCP-GC) for the resistance welding applications by combining a phase-shifted full-bridge converter and a new multi-function pulse generator. The proposed BVCP-GCT consists of a phase shifted full bridge (PSFB) converter as the first stage and the proposed multi-functional pulse generator as the second stage, which can generate unipolar and bipolar voltage pulses as well as unipolar and bipolar current pulses. The detailed operation principles and key characteristics of the proposed converter are also given. Finally, a reduced experimental prototype was developed. Experimental results verify that the proposed converter can generate positive-voltage pulses, negative-voltage pulses, bipolar-voltage pulses, and bipolar-current pulses.

Non-magnetic steels are essential for applications requiring both high mechanical strength and strict magnetic neutrality, such as superconducting systems and nuclear engineering. However, conventional strengthening methods often deteriorate magnetic stability, leading to a persistent trade-off between strength and magnetism. Here, we show that ultrasonic impact treatment (UIT) effectively overcomes this limitation by inducing a gradient dislocation structure that enhances mechanical properties while triggering a near-complete body-centered cubic (BCC) to face-centered cubic (FCC) reverse martensitic transformation in medium-Mn steel, forming a fully austenitic surface layer that suppresses ferromagnetism. Micropillar compression tests show simultaneous increases of similar to 138% in strength and similar to 96% in plasticity compared with the untreated counterparts, attributed to the gradient dislocation structure. The gradient layer also exhibits nearly doubled wear resistance relative to commercial non-magnetic steels. Atomic-scale analysis further reveals a shear-mediated BCC-to-FCC reverse transformation pathway that challenges the classical Bogers-Burgers model, where the BCC lattice first distorts into an intermediate structure and then evolves into FCC through sequential shear. These findings establish UIT as a promising route to design non-magnetic steels with enhanced mechanical performance and magnetic stability. (c) 2026 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

This article proposes a novel zero current switching (ZCS) soft-switching quadratic three-level boost converter with passive snubber circuit. The proposed converter is consist of the quadratic circuit of three-level boost converter and a ZCS circuit with three advantages: the ZCS soft-switching auxiliary circuit improves the efficiency of the converter; the quadratic structure improves the voltage gain; the three-level structure reduces the voltage stress. This article presents the principle of operation, voltage stress, power loss and soft-switching conditions. Finally, a 450 W experimental prototype was built and tested. The experimental results show that the main switches of this proposed converter can obtain ZCS condition in the whole output power range, and the peak efficiency reaches 97%.

In this paper, a novel zero-voltage switching (ZVS) synchronous rectification (SR) boost converter with a coupled inductor-capacitor (LC) circuit is proposed. This ZVS SR boost converter employs a transformer (coupled inductor), a capacitor, an inductor, and a diode as the ZVS auxiliary circuit. The new auxiliary circuit utilizes an LC resonant circuit as the energy source and uses a coupled inductor to generate a unidirectional triangular wave current from this energy source, thereby providing ZVS conditions to the main switch of the boost converter. The detailed operating principle, soft-switching limitations, voltage, and current stress are presented. Moreover, the proposed converter is compared with the existing soft-switching DC/DC converters to verify its superiority. Finally, a 300 W experimental prototype is developed, and the key waveforms and efficiency are measured. The experimental results are consistent with the theoretical analysis. They also show that both transistors of the proposed converter can operate under ZVS conditions. The peak efficiency of the proposed converter reaches 97.24%.

Copper alloys are widely used due to their excellent electrical and thermal conductivity. However, their poor wear resistance and high-temperature oxidation resistance limit their applications and service life. In this study, a laser-induced oxidation (LIO) pretreatment combined with PEO (LIO-PEO) was employed to fabricate a dense in-situ ceramic coating on a non-valve CuCrZr alloy substrate. High-speed imaging, confocal microscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to investigate the coating formation and characteristics. LIO generated a uniform Cu2O layer, reducing breakdown voltage and promoting soft-spark discharges. The LIO-PEO coating showed fivefold higher wear resistance than the substrate and the conventional PEO treatment. After 20 h of oxidation at 600 degrees C, mass losses were 3.2 % (substrate), 4.2 % (PEO), and 2.4 % (LIO-PEO) respectively, confirming superior oxidation resistance for the LIO-PEO sample. The proposed mechanism suggests that LIO creates an oxide layer on valve metal, facilitates soft spark initiation and enables effective substrate incorporation into the ceramic coating.

This work proposed a simple bionic-inspired strategy to in situ construct a root-like interfacial interlocked structure in the refractory high-entropy alloys (RHEA) particle-reinforced Ni matrix composites by activated sintering. The results showed that at the RHEA-Ni interface, Ni element preferred to aggregate inside the RHEA near the interface by grain boundaries (GBs) wetting and far away from the interface by GBs prewetting. Subsequently, the Ni-rich liquid-like film crystallized into Ni3(Ta, Nb), Ni2(Ta, Nb) phases due to relatively low Gibbs free energy change (Delta G) and high diffusion rate, in situ forming root-like interlocked structure anchored on the RHEA particle. At the root-like interlocked interface, the Ni-Ta intermetallic compounds (IMCs) and BCC phase, serving as alternating hard and soft oriented phases, enhance the interlocked interface hardness and elastic modulus. The finite element method proved that the root-like interlocked structure reduced the demand for interfacial reaction layer strength and the degree of interfacial stress concentration. Compared to the pure Ni bulk, the 10 vol% RHEA/Ni composite obtains 41.8 % and 93.4 % in ultimate tensile strength (UTS) to 509 MPa and yield strength (YS) to 205 MPa, respectively, while maintaining an acceptable elongation of 15.8 %. This work offers a novel approach to in situ synthesize the bionic configuration interface structure for the enhanced interfacial bonding and optimized interfacial stress distribution of the Ni matrix composites.

The microstructure and impact toughness of the weld were examined after welding X80 pipeline steel using the pulsed MAG(Metal-Active Gas) method, with TiO2 nanoparticles (20 nm) added to the weld. This analysis employed various material characterization techniques. The results show that the weld Microstructure primarily consists of acicular ferrite (AF), granular bainite (GB), polygonal ferrite (PF). The addition of nano-TiO2 to the weld increased the acicular ferrite content and led to the formation of oxides with Ti-Mn-O-Si-Al as the main constituents. These oxides feature an Al2O3 outer layer coated with MnTi2O4-Ti2O3-type oxides, which effectively promote AF nucleation and refine the weld microstructure. Nano-TiO2 oxide inclusions were shown to facilitate AF nucleation via two mechanisms: the Mn-depletion zone (MDZ) mechanism and the low lattice mismatch mechanism. However, not all oxide inclusions were observed to induce nucleation through the low lattice mismatch between AF and oxide inclusions. The average impact energy measured in the weld at a temperature of -40 degrees C was increased by 22.06 % with the addition of nano-TiO2 (83J) compared to the weld without nano-TiO2 (68 J). This improvement is attributed to the higher energy required for crack propagation in AF compared to GB. As such, the increased AF content in the weld effectively hinders crack propagation, thereby enhancing the weld's impact toughness. Furthermore, the reduction in average weld grain size from 7.14 mu m to 5.14 mu m and the apparent increase in misorientation angles of 45 degrees or higher corroborate the observed improvement in low-temperature impact toughness.

The work aims to study the effect of ultrasonic pulse energy on the film formation process,microstructure,morphology,and corrosion resistance of micro-arc oxidation(MAO)coatings on AZ31B magnesium alloy,to further analyze the film formation mechanism.By varying the ultrasonic pulse frequency(50,100,150 kHz)to adjust the pulse energy,micro-arc oxidation was performed on the surface of the AZ31B magnesium alloy substrate in a silicate system.The surface morphology,elemental composition and phase structure of the coating were analyzed by laser confocal microscopy,SEM/EDS and XRD.The corrosion resistance of the coating was characterized through electrochemical testing.The phase composition of the micro-arc oxidation coating prepared in the silicate system mainly consisted of MgO and Mg2SiO4.As the ultrasonic pulse frequency increased,the pulse energy decreased,leading to an extended arc initiation time during the MAO process,a reduction of the micropores diameter,and an improvement in the uniformity of the coating surface.Compared with the substrate,the MAO coating prepared under ultrasonic pulse conditions exhibited an increase in self-corrosion potential by 1.5 V and a reduction in self-corrosion current density by 3 to 4 orders of magnitude.In conclusion,ultrasonic pulses voltage significantly affects the microstructure of magnesium alloy MAO coatings and enhances the uniformity of the coatings.With the increase of pulse frequency,which corresponds to a decrease of pulse energy,the size of the arcs during the MAO process reduces,and the number of arcs increases.Consequently,the size and diameter of the micropores on the surface of the MAO coating are reduced.At the same time,it also reduces the thickness of the loose layer and increases the thickness of the dense layer,which is great beneficial to improve the corrosion resistance of the coatings.

In this study, continuous fiber laser was used to butt weld 2 mm thick 4047 and 6061 dissimilar aluminum alloys, and the optimization of welding parameters, microstructure and mechanical properties of the joint were studied. The Box-Behnken Design (BBD) response surface test design method was used to optimize three main process parameters: laser power, welding speed and defocusing amount. The optimal process parameter combination was determined as follows: laser power 800 W, welding speed 17.5 mm/s, defocusing amount 0 mm. The accuracy of the prediction model of back-width ratio and effective area under this parameter is as high as 97 % compared with the reality. The welded joint with good weld shape and no defects was obtained. The microstructure of the weld is mainly composed of alpha-Al matrix and Al-Si eutectic structure, the center of the weld is equiaxed crystal structure, and the near melting zone is columnar dendrite. The main alloy elements of the weld are Al, Si, Mg and Fe, and there is no obvious element segregation. The longitudinal local tensile results show that the tensile strength of the weld metal reaches 260.45 MPa, which is 202.6 % and 83.3 % of the 4047 base metal and 6061 base metal respectively. The elongation is 12.25 %, which is 43.9 % and 98.2 % of 4047 and 6061 base materials, respectively. The above research provides a reference for the connection and application of 4047/6061 dissimilar aluminum alloy.

The present study investigates the influence of Al-Si substitution on the shot peening (SP) response of mediumMn steels. A series of alloys with different Al/Si ratios were designed while maintaining a nearly constant total (Al + Si) content of approximately 2.5 wt%. The aim was to clarify how compositional variations modify the deformation behavior, microstructural evolution, and surface strengthening characteristics during SP. The results indicate that the Al-Si ratio plays a crucial role in determining the deformation mode and surface response of medium-Mn steels. With increasing Si content, the deformation behavior gradually changes from dislocation slip-dominated to twinning- and transformation-assisted modes, resulting in enhanced grain refinement and surface hardening. Si-rich alloys exhibited a more refined surface microstructure, deeper plastically affected layer, and higher compressive residual stress compared with the Al-rich alloy. The surface hardness of all alloys significantly increased after SP, and the hardening depth was closely related to the alloy composition. These findings suggest that the substitution of Al and Si influences the SP-induced strengthening behavior primarily through composition-dependent deformation mechanisms. This work provides experimental evidence for understanding the relationship between alloy chemistry, microstructural evolution, and surface strengthening, offering guidance for the compositional design and surface optimization of high-performance medium-Mn steels.

A nickel ferrite (NiFe2O4) coating was deposited onto a Ni-Fe-Co-Cu (NFCC) alloy anode via plasma spraying, followed by a high-temperature pre-oxidation treatment to densify the coating and seal surface porosity. Electrolysis experiments were conducted at 850 degrees C in a NaF-KF-AlF3 molten salt electrolyte (CR=1.40) with a current density of 0.75 A/cm2 using both uncoated (NFCC) and a coated version alloy anode referred to as NFCC-SL (sprayed and oxidized NiFe2O4 layer). The pre-formed NiFe2O4 layer effectively prevented the direct diffusion of the alloy substrate, suppressing dissolution and enhancing corrosion resistance. Additionally, the coating enabled horizontal diffusion of Ni and Fe during electrolysis, promoting the formation of a secondary NiFe2O4 layer. As a result, the impurity content in the produced aluminum was significantly reduced. The combined barrier effect of the sprayed and regenerated oxide layers demonstrates this coating's potential for improving non-carbon anode performance in aluminum electrolysis.

A new nanostructured ZrB2-ZrC composite coating with ZrB2-ZrC nanoscale eutectic and ZrB2+Amorphous microstructure was synthesized in situ by plasma spraying Zr-B4C-Al composite powder. The thermal analysis, quenching experiments and microstructure characterization were investigated and the formation mechanism of the bimodal in-situ microstructure was revealed. Al contributed to the liquid phase separation of molten droplets, which is the key to forming ZrB2+Amorphous microstructure. The formation of coating followed reaction-melting-liquid separation-deposition and solidification mechanism. The nanostructured ZrB2-ZrC composite coating with Al-O intergranular amorphous phase has excellent mechanical properties. The uniform nano-grains improved the hardness and the toughness of the ZrB2-ZrC eutectic. The ZrB2+Al-O amorphous microstructure obtained high toughness and the toughening mechanism was the crack deflection and crack branching caused by intergranular Al-O amorphous phase.

A novel bypass-gas metal arc directed energy deposition (bypass-GMA DED) was proposed to prepare high strength Al-Cu-Li-based components. An Al-5.51Cu-0.48Li alloy was successfully prepared, followed by subsequent T6 treatment. The microstructure evolution and improvement of mechanical properties after the T6 state were benchmarked against the as-deposited condition. The component fabricated by bypass-GMA DED has obvious periodic distribution characteristics, with a large number of fine equiaxed grains distributed near the interlayer fusion boundary and coarse columnar grains within the intralayer region. After heat treatment, the Al-5.51Cu-0.48Li alloy is mainly composed of four types of strengthening phases, theta ', theta '', delta ' and T1, which contrasts with the sole presence of theta phase in the deposited condition. These phases are conducive to the improvement of mechanical properties. The strength of the prepared alloy is higher than those additively manufactured Al-Cu-Li alloys, reaching values similar to those of conventional third generation Al-Cu-Li alloys.