Radially graded porous architectures offer advantages over uniformly porous structures in meeting the heterogeneous mechanical and biological requirements of complex bone defects. In this study, the radially graded Fe-35Mn scaffolds based on Gyroid unit cells were successfully manufactured using selective laser melting and subsequently functionalized by vacuum impregnation with human bone morphogenetic protein-2 (BMP-2)-loaded chitosan. The Fe-35Mn scaffolds exhibit a well-interconnected porous structure with ∼53-66% porosity and an average pore size ranging from ∼138 to 483 μm. The microstructure is dominated by γ-austenite with a minor fraction of ε-martensite. The radially graded Fe-35Mn scaffolds possess elastic moduli of 2.4-3.5 GPa and compressive yield strengths of 40.9-67.7 MPa, comparable to those of cortical bone and favorable for minimizing stress shielding while maintaining sufficient load-bearing capacity. The degradation rates of the porous scaffolds in simulated body fluid decrease with immersion time, reaching approximately 0.14-0.23 mm·year-1 after 28 days, which is moderately higher than that of the dense Fe-35Mn alloy (∼0.092 mm·year-1). Moreover, the BMP-2-loaded scaffolds display a biphasic release behavior, characterized by an initial burst release up to 168 h followed by a slower, sustained release from 168 to 456 h. Overall, these results demonstrate that radially graded porous Fe-35Mn scaffolds combine favorable mechanical compatibility, tunable biodegradation, and sustained growth factor delivery, highlighting their potential as biodegradable load-bearing scaffolds for bone regeneration.

Biodegradable iron (Fe)-based alloys represent a promising class of biomaterials due to their exceptional mechanical properties and biocompatibility. However, their clinical translation is hindered by slow degradation rates resulting from the formation of protective oxide layers. This study addresses this challenge by investigating Fe-36.8Mn-6Si alloy fabricated via mechanical alloying and spark plasma sintering (SPS) at low temperatures (650–750°C). The study systematically evaluates the effects of sintering temperature on microstructure, mechanical performance, and corrosion behavior in Hanks’ Balanced Salt Solution. Microstructural analysis reveals that elevated sintering temperatures enhance atomic diffusion, promoting densification through sintering neck growth and pore elimination. At 750°C, the alloy achieves a relative density above 98 % and exhibits optimal mechanical properties. Higher sintering temperatures reduce corrosion current density and mass loss rates of sintered alloys. Surface characterization after immersion reveals that lower-temperature sintered alloys develop thick, porous corrosion product layers rich in calcium phosphates and hydroxides, whereas higher-temperature specimens form sparse, localized deposits. This work underscores the potential of low-temperature SPS in engineering biodegradable metals with tailored microstructures for enhanced performance.

Metal Digital light processing (MDLP) offers high resolution and excellent surface quality, but the final properties of printed parts are highly dependent on post-processing. In this study, the effects of debinding, decarburization, and sintering on the shape fidelity, microstructure, and mechanical properties of MDLP-fabricated 316L stainless steel were systematically investigated. The optimal post-processing route consisted of debinding in an inert atmosphere, decarburization in air within 400-600 °C, and sintering at 1370 °C for 4 h under flowing nitrogen. Under these conditions, the sintered parts achieved a relative density of 98.03 ± 0.23%, hardness of 380.63 ± 9.15 HV, elastic modulus of 213.47 ± 5.5 GPa, tensile strength of 519.7 ± 22 MPa, and elongation at fracture of 76.8 ± 9.3%. Microstructural analysis showed that increasing the sintering temperature reduced porosity and smoothed the morphology of Cr-rich oxygen-containing second phase regions, thereby alleviating stress concentration and improving mechanical properties. This study provides an effective post-processing strategy for MDLP-fabricated 316L stainless steel and examines the microstructural origins of the observed property evolution.

Hexagonal boron nitride nanoplatelets (BNNPs) are promising nanofillers for Mg matrix composites owing to their excellent mechanical properties and low density. In this research, we report the fabrication of ZK61 magnesium composites reinforced with a hybrid of BNNPs and β-tricalcium phosphate (TCP) using spark plasma sintering (SPS). The designed composites exhibit a dense microstructure characterized by refined α-Mg grains with β-TCP particles preferentially distributed along the α-Mg particle boundaries. In addition, trace amounts of interfacial products, such as Mg3N2 and MgB2, are detected to act as chemical anchoring phases, promoting stronger interfacial bonding. Notably, the composite containing 5.0 wt % β-TCP and 0.3 wt % BNNPs demonstrates a remarkable combination of strength and ductility, exhibiting a compressive yield strength of ∼132 MPa, an ultimate compressive strength of ∼380 MPa, and an elongation of ∼28.9%. This favorable balance of high strength and substantial plastic deformability highlights the synergistic reinforcing effect of β-TCP and BNNPs in the ZK61 matrix. In addition, immersion tests reveal that the degradation rate of the 0.3BNNP/5TCP/ZK61 composite is approximately one-fourth that of the monolithic ZK61 alloy immersed in SBF for 28 d. These findings suggest that BNNP/β-TCP reinforced ZK61 composites are promising candidates for biodegradable implant materials.

To improve the efficiency of passive cooling systems for battery thermal management system (BTMS), this work innovatively utilizes the synergistic effect of flexible materials and high thermal conductivity materials. A flexible composite phase change material (FCPCM) with good adhesion, high thermal conductivity and high enthalpy was prepared using paraffin wax, expanded graphite, a polyester-based flexible matrix, and micro-copper powder. To characterize the material properties, the key thermal properties of FCPCM were verified through experiments. Battery pack charging and discharging experiments are designed, analyzed and compared to show the changes in the temperature field inside the battery pack before and after FCPCM cooling. The results show that the thermal conductivity of the prepared FCPCM is 2.72 W/(m & sdot;K) and the interface thermal resistance is 0.561 degrees C/W. At a 3C discharge rate, the maximum temperature inside the battery pack with passive FCPCM dropped from 71.5 degrees C to 39.3 degrees C, and the maximum temperature difference was 4.23 degrees C. The battery operated consistently within its optimal temperature range (20 degrees C-40 degrees C). This research provides a passive thermal management solution that meets the functional requirements for BTMS.

Lithium-ion batteries play a crucial role in electric vehicles (EVs) owing to their high energy density and long cycle life. However, maintaining their operating temperature within the optimal range requires advanced battery thermal management systems (BTMS) to meet the ever-evolving performance requirements of EVs. The purpose of this study is to effectively integrate liquid cooling with composite phase change material (CPCM) cooling and to enhance the contribution of the heat transfer performance of phase change materials to BTMS efficiency by adopting an innovative multilayer phase change material structure. To better analyze the characteristics of water flow direction, cooling plate width, inlet flow rate, CPCM doping ratio, multilayer CPCM structure, and battery pack temperature distribution in the composite thermal management system, the charging and discharging thermal behaviors of the battery were simulated and verified. The results indicate that the BTMS proposed in this study can significantly improve the temperature field distribution within the battery pack. Specifically, under an ambient temperature of 298.15 K, a water flow rate of 1 L min−1 and a 2C discharge rate, the BTMS based on multilayer CPCM coupling can reduce the maximum internal temperature of the battery pack to 303.93 K, with a maximum temperature difference of only 1.1 K. Compared with the scenario without cooling, the maximum temperature is reduced by 27.02 K, and the maximum temperature difference is reduced by 8.1 K. This study provides an efficient solution for the design and optimization of BTMS in EV lithium-ion batteries.

Metal digital light processing (MDLP) has emerged as a promising route for high-precision metal additive manufacturing (AM), owing to its capability to produce parts with excellent surface quality and fine geometric features. However, its practical application remains limited by the persistent trade-off among curing depth, solid loading, and feedstock stability, particularly for high-density, optically absorptive metal systems. Herein, we report a formulation-driven strategy to address these coupled challenges by simultaneously tailoring the printability, photocuring performance, and stability of a 316L stainless steel (316L SS) photosensitive paste, without relying on particle surface modification, auxiliary heating, or real-time mixing. A high solid loading of 50 vol% was achieved while maintaining a sufficient curing depth of approximately 56 mu m through photoinitiator-wavelength matching and resin functionality optimization. Meanwhile, long-term feedstock stability for more than 24 h was realized by incorporating a shear-reversible thixotropic network, which enabled uniform recoating under blade-induced shear and effectively suppressed sedimentation during rest periods. As a result, complex 316L SS parts with high dimensional accuracy and excellent surface quality were successfully fabricated. After debinding and sintering, the parts exhibited a tensile strength of 511.2 +/- 22.0 MPa and a fracture elongation of 69.1 +/- 9.3%, demonstrating a favorable strength-ductility combination compared with reported values for indirectly additively manufactured 316L SS parts. This work establishes a practical and scalable pastebased formulation strategy for MDLP and provides guidance for extending vat photopolymerization to highdensity, optically absorptive metal systems.

For pulsed-current assisted diffusion bonding of ZrC-SiC composite, the required joining temperature and joint formation mechanism showed great difference with grain-size. Compared to base-materials with a grain-size of 3-5 mu m (m-ZS), the joining temperature of n-ZS (grain-size-1 mu m) could be reduced by 100 degrees C while maintaining the same joint efficiency. Moreover, the straight bond-line of m-ZS joint was eliminated by strain-induced grain-boundary migration, but causing by the straight interface due to the pining effect of interfacial SiC, shear strength of the joint bonded at 1700 degrees C is only 81.7 % of the substrate. In contrast, pulsed-current enhanced the vaporization-deposition mechanism in n-ZS joint, resulting in massive formation of nano-scale ZrC particles at interface. At 1700 degrees C, the cross-interface growth of nano-particles contributed to a seamless joining, and the joint microstructure and shear strength are consistent with those of the base-materials.

The performance and life of lithium-ion batteries are very sensitive to temperature, therefore, maintaining the proper temperature range is important for battery applications. However, localized high temperature regions within the battery are the main cause of temperature non-uniformity or even thermal runaway of the battery, so it is necessary to implement thermal management for these critical regions. In this paper, a thermal management cooling system utilizing liquid cooling and multilayer composite phase change materials (CPCM) is introduced. This article explored the effectiveness of different material in thermal management and designed a multi-layer phase change material structure to increase the thermal conductivity of the high heat region, in order to further reduce the temperature difference within the battery pack. By combining liquid cooling with CPCM cooling, this article proposes a composite thermal management system (BTMS) that places greater emphasis on thermal management efficiency. The results showed that the combined BTMS successfully reduced the maximum internal temperature of the battery pack to 29.18 degrees C, with a maximum temperature difference of only 1.82 degrees C, thereby improving the performance of the system. The combination of liquid and phase change cooling in BTMS can provide new technical support for improving the lifespan and safety of battery packs.

The most appealing features of chip-scale quantum sensors are their capability to maintain extreme sensitivity while enabling large-scale batch manufacturing. This necessitates high-level integration and wafer-level fabrication of atomic vapor cells. In this paper, we describe a micromachining paradigm for wafer-level atomic vapor cells functionalized by CMOS-compatible non-magnetic heaters and temperature sensors and demonstrate several innovative applications. Leveraging standard micro-nanofabrication technology, the integrated vapor cells achieved an ultra-long optical access of 5 mm, nearly four time that of previously microfabricated vapor cells. The feasibility of the integrated atomic vapor cells fabrication process was verified by a consecutive 30-day aging test in a harsh environment (operating temperature of 473 K and vacuum of approximately 1 Pa). Benefiting from the ultra-long optical path, we observed several typical quantum effects, including the saturation absorption and spin fluctuations, a regime previously inaccessible with conventional micromachined vapor cells. Finally, a zero-field quantum magnetometry with an ultra-high magnetic sensitivity of 12 fT/Hz1/2 was also demonstrated. Our achievements broaden the potential applications of microfabricated atomic vapor cells and pave the way for scalable manufacturing of ultrasensitive, chip-scale quantum sensors.

The aim of this research is to explore the tribological behavior of graphene nanosheet (GNS) reinforced hydroxyapatite (HA) coatings deposited using atmospheric plasma spraying on Ti6Al4V substrate for biomedical applications. The results presented herein demonstrate that, under the investigated tribocorrosion conditions, plasma-sprayed GNS/HA composite coatings exhibit lower coefficients of friction (similar to 0.324-similar to 0.361) and improved wear resistance as compared to monolithic HA coating. In particular, the HA composite coating with 2.0 wt% GNSs displays a remarkable reduction in the wear rate by up to 28.7 % at 40 N. The enhanced tribocorrosion performance of the GNS/HA coatings can be attributable to improved damage tolerance of the composite coatings during wear test, resulting from the simultaneous improvements in strength and toughness, as well as enhanced corrosion resistance in simulated body fluid (SBF), where these GNSs act as an inert physical barrier against the corrosive environment.

Atomic magnetometers, a prominent class of quantum sensors, have become increasingly significant in magnetometry, with extensive applications in cutting-edge physics, biomedical imaging, industrial inspection, and beyond. However, the power consumption of an atomic magnetometer is primarily dominated by that demanded to heat the atomic vapor cell to its operating temperature. This operating temperature determines the alkali-metal atomic density, thereby influencing the magnetic field sensitivity and overall power consumption, which poses a potential obstacle to the large-scale engineering application of atomic magnetometers. In this article, a novel heating method utilizing renewable solar energy is proposed for the first time, which can surpass the limitation of conventional heating methods in thermo-atom-based quantum sensors. By exploiting an intelligent closed-loop control system to adaptively regulate the functionalized sunlight power, this proposed method has the capability of both high heating efficiency and accuracy. The heating properties and laser absorption spectrum at different temperatures up to 180 °C are characterized substantiating the feasibility of utilizing sunlight. Moreover, a sunlight-heated, highly sensitive, microfabricated atomic magnetometer with a magnetic field sensitivity of 18 fT/Hz 1/2 is demonstrated. And the single-chamber microelectromechanical system atomic vapor cell as the key component is fabricated by utilizing deep silicon micromachining and anodic bonding techniques. This proposed technique can be further extended to all quantum sensing systems based on thermal atomic ensembles and open up new possibilities for the development of self-powered, environmentally friendly quantum sensors.

Copper matrix composites reinforced with hard reinforcements typically exhibited increased strength, often at the expense of ductility and electrical conductivity. In this work, reduced graphene oxide (RGO)/Cu composites with a laminated structure were developed to balance these properties. Microstructural analysis highlights the intercalation of RGO layers creating a distinctive laminated structure. At the RGO-Cu interfaces, traces of CuO and Cu2O serve as chemical anchors, enhancing interface strength. With a minimal graphene content of only 0.024 vol %, the composite achieves a yield strength of 240 MPa and a strengthening efficiency of 572, while preserving elongation and electrical conductivity at comparable levels to the pure Cu sample (36.4% and 97.1% IACS, respectively). The composites are reinforced through several mechanisms: load transfer, the Orowan mechanism, and grain refinement, which collectively enhance the strength. Additionally, they are toughened by the formation of interlaminar copper (Cu) pillars, which effectively resist tearing. Furthermore, the unidirectional alignment of the RGO within these structures facilitates efficient electron transport, contributing to good electrical performance. The results presented demonstrate that this research successfully balances several mutually exclusive properties in metal matrix composites such as strength, ductility, and electrical conductivity. This achievement provides a promising direction for the development of advanced metal matrix composites.

Ceramic vat photopolymerization (VPP) enables the fabrication of complex components with excellent properties and high precision. However, compared with metals and polymers, the industrial application of ceramic VPPs remains relatively limited. This can be attributed to the challenges associated with ceramic feedstock printability, the complexity of the printing process, insufficient performance evaluation, and service verification. To overcome these limitations, the design of a viscoelastic paste and corresponding VPP strategies offer a promising solution. This paper presents a review of the research on the state of viscoelastic ceramic paste-based VPP. The main technical aspects, including the paste design, support strategies, green-body cleaning, and subsequent post-treatment, are discussed. Furthermore, representative applications of VPP for various types of advanced ceramics are surveyed. This review also highlights the technical challenges involved and provides suggestions for addressing these issues. Finally, future directions for promoting the additive manufacturing of advanced ceramic components with enhanced efficiency and reliability are discussed.

The practical applications of magnesium (Mg) alloys are usually beset by their relatively low strength and limited ductility. Herein we attempt to fabricate hexagonal BN nanoplatelet (BNNP) reinforced ZK61 magnesium composites using a combination of spark plasma sintering and friction stir processing. The resulting composites exhibit microstructural characteristics of homogeneous dispersion of BNNP in Mg matrix with refined equiaxed grains and (0002) basal texture roughly surrounding the pin column surface. Transmission electron microscopy observation illustrates that trace amounts of Mg3N2 and MgB2 form at BNNP-Mg interface, in which Mg3N2 locates at the basal plane of a BNNP and MgB2 grows at its open edge. The spatial distribution of Mg3N2 and MgB2 facilitates interfacial wetting and stronger BNNP-Mg interface in such a way that interfacial products act as anchors bonding between them. In comparison with monolithic ZK61 alloy, the BNNP/ZK61 composites display simultaneous improvements in yield strength, hardness and ductility, achieving good strength-ductility balance. This research is expected to shed some light on BNNP potentials for designing and producing magnesium composites with high strength and good ductility.

In this study, the bulk Cu/reduced graphene oxide (Cu/rGO) composites featuring an artificial nacre-like laminated structure were successfully fabricated using spark plasma sintering (SPS), and the microstructure and mechanical properties of the resulting composites were investigated. The Cu/rGO composites demonstrated a distinct laminated structure, and their relative densities increase with Cu addition. Moreover, the presence of trace amounts of in-situ interfacial reaction products (CuO and CuO2,) were observed to enhance the adhesive strength at the Cu-rGO interface. Mechanical testing of the composites showed notable improvements in both compressive strength and ductility compared to a bulk monolithic rGO sample. Specifically, the bulk rGO composites with a 35.05 wt% addition of Cu displayed an enhancement of similar to 67 % in compressive strength and similar to 19 % in ductility relative to the pure rGO sample. These improvements are attributed to synergetic strengthening and toughening mechanisms within the rGO composites. The enhanced strength and ductility of the Cu/rGO composites significantly boost their wear resistance. This research not only demonstrates the effectiveness of incorporating Cu into rGO matrices but also suggests a promising avenue for the development of novel bulk rGO composites with engineered laminated structures.

Corrosion behavior of Ti6Al4V and rGO/Ti6Al4V composites fabricated by spark plasma sintering (SPS) was systematically investigated in stimulated body fluid (SBF) using electrochemical measurements including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Results showed that the rGO/Ti6Al4V composites exhibit enhanced corrosion resistance, especially corrosion rate of the 0.54rGO/Ti6Al4V composite (∼7.10×10−4 g·m−2·h−1) is only about one-seventh of that of monolithic Ti6Al4V (∼48.3×10−4 g·m−2·h−1). As compared with Ti6Al4V sample, preferential dissolution of the rGO/Ti6Al4V composites are liable to occur in the early SBF immersion stage, and rGO is believed to do credit to rapid passivation on the composite surface in virtue of the added rGO with excellent electric conductivity acting as the micro-cathode and fine basket-weave microstructure induced by these rGO. Meanwhile, the inherent inert and hydrophobic nature of rGO within the passivation film would act as a barrier to resist infiltration of halide ion, and therefore the addition of rGO into Ti6Al4V matrix is capable of inhibiting localized breakdown of passive film. Above results strongly suggest that rGO/Ti6Al4V composite could be a promising candidate for biomedical applications.

The Ti-4Al-2V (wt. %) titanium alloy has garnered widespread applications across diverse fields due to its exceptional strength-to-weight ratio, high toughness, specific strength, and corrosion resistance. The welding of Ti-4Al-2V titanium alloy components is often necessary in manufacturing processes, where the reliability of a welded joint critically influences the overall service life of these components. Consequently, a comprehensive understanding of the welded joint’s microstructure and mechanical properties is imperative. In this study, Ti-4Al-2V titanium alloy was welded using multi-layer and multi-pass TIG welding techniques, and a detailed examination was conducted to analyze the microstructure and grain morphology of each microzone of the welded joint. The results revealed the presence of an initial α phase and a secondary lamellar α phase in the heat affected zone (HAZ). Meanwhile, the fusion zone (FZ) primarily comprised a coarse secondary α phase and a small amount of an acicular martensitic α’ phase. Both the recrystallization zone and the superheated zone exhibited a distinct preferred orientation, with grains smaller than 10 μm accounting for 65.9% and 55.1%, respectively. To assess the mechanical properties of the various microzones and the typical microstructure within the welded joint, nanoindentation tests were performed. The results indicated that the recrystallization zone possessed a higher nanohardness (3.753 GPa) than the incomplete recrystallization zone (3.563 GPa) and the superheated zone (3.48 GPa). Among all the microzones, the FZ exhibited the lowest average nanohardness (3.058 GPa). Notably, the basket-weave microstructure demonstrated the highest average nanohardness, reaching 3.93 GPa. This was followed by the fine-grain microstructure, which possessed a slightly lower nanohardness. The Widmanstätten microstructure, on the other hand, exhibited the lowest nanohardness among the three microstructures within the HAZ. Therefore, the basket-weave microstructure stands out as the most desirable microstructure to achieve in the welded joint. In summary, this study provides a comprehensive characterization and analysis of the microstructure and properties of Ti-4Al-2V titanium alloy TIG welds, aiming to contribute to the optimization of the TIG welding process for Ti-4Al-2V titanium alloy.

Triply periodic minimal surface structures (TPMS) have garnered significant attention owing to their exceptional mechanical properties, biomimetic curvature attributes, and favorable printability characteristics. Nonetheless, existing design methodologies for porous structures exhibit certain limitations. In particular, the Boolean operation method can result in damaged boundary cells within intricate models. This research introduces a non-proportionally scaled deformation model approach for generating the Gyroid Square Become Circle (GSBC) structure with an integrated boundary. Following fabrication through selective laser melting of NiTi, morphological assessments conducted via scanning electron microscopy and 3D reconstructions affirmed its printability. The compression behavior of GSBC was investigated through finite element simulations and compression testing, comparing to traditional Gyroid Boolean Intersection Operation (GBIO) structures. The findings revealed that GSBC exhibited superior compression performance and enhanced energy absorption capacity. A comprehensive analysis was carried out, encompassing porosity, CT reconstruction outcomes, inclination angles, curvature distribution characteristics, and failure mechanisms. The examination of inclination angles demonstrated a discernible correlation between the inclination angle and stress distribution under uniaxial compression loading conditions. This study is poised to offer valuable insights into the design and utilization of TPMS-based models for complex structures, along with the integration of mechanical properties in porous structures.

Ti6Al4V scaffolds were successfully fabricated using selective laser melting followed by vacuum impregnation of gentamicin loaded chitosan. Microstructural observation revealed that Ti6Al4V scaffolds display primary columnar β grains, in which a hierarchical structure of acicular α′ martensites of varying sizes was observed. Compressive tests indicated that a scaffold with 59