Three-dimensional (3D) printing allows for the creation of complex, layered structures with precise micro and macro architectures that are not achievable through traditional methods. By designing 3D structures with geometric precision, it is possible to achieve selective regulation of mechanical properties, enabling efficient dissipation of mechanical energy. In this study, a series of modular samples inspired by the Bouligand structure were designed and produced using a direct ink writing system, along with a classical printable polydimethylsiloxane ink. By altering the angles of filaments in adjacent layers (from 30° to 90°) and the filament spacing during printing (from 0.8 mm to 2.4 mm), the mechanical properties of these modular samples can be adjusted. Compression mechanical testing revealed that the 3D printed modular Bouligand structures exhibit stress-strain responses that enable multiple adjustments of the elastic modulus from 0.06 MPa to over 0.8 MPa. The mechanical properties were adjusted more than 10 times in printed samples prepared using uniform materials. The gradient control mechanism of mechanical properties during this process was analyzed using finite element analysis. Finally, 3D printed customized modular Bouligand structures can be assembled to create an array with Bouligand structures displaying various orientations and interlayer details tailored to specific requirements. By decomposing the original Bouligand structure and then assembling the modular samples into a specialized array, this research aims to provide parameters for achieving gradient energy absorption structures through modular 3D printing.

Soft magnetic composites (SMCs) play a pivotal role in the development of high-frequency, miniaturization and complex forming of modern electronics. However, they usually suffer from a trade-off between high magnetization and good magnetic softness (high permeability and low core loss). In this work, utilizing the order modulation strategy, a critical state in a FeSiBCCr amorphous soft magnetic composite (ASMC), consisting of massive crystal-like orders (CLOs, ∼1 nm in size) with the feature of α-Fe, is designed. This critical-state structure endows the amorphous powder with the enhanced ferromagnetic exchange interactions and the optimized magnetic domains with uniform orientation and fewer micro-vortex dots. Superior comprehensive soft magnetic properties at high frequency emerge in the ASMC, such as a high saturation magnetization (M_s) of 170 emu g⁻¹ and effective permeability (μ_e) of 65 combined with a core loss (P_cv) as low as 70 mW cm⁻³ (0.01 T, 1 MHz). This study provides a new strategy for the development of high-frequency ASMCs, possessing suitable comprehensive soft magnetic performance to match the requirements of the modern magnetic devices used in the third-generation semiconductors and new energy fields.

Amorphous Ga₂O₃ (a-Ga₂O₃) has been attracting more and more attention due to its unique merits such as wide bandgap (∼4.9 eV), low growth temperature, large-scale uniformity, low cost and energy efficient, making it a powerful competitor in flexible deep ultraviolet (UV) photodetection. Although the responsivity of the ever-reported a-Ga₂O₃ UV photodetectors (PDs) is usually in the level of hundreds of A/W, it is often accompanied by a large dark current due to the presence of abundant oxygen vacancy (V_O) defects, which severely limits the possibility to detect weak signals and achieve versatile applications. In this work, the V_O defects in a-Ga₂O₃ thin films are successfully passivated by in-situ hydrogen doping during the magnetron sputtering process. As a result, the dark current of a-Ga₂O₃ UV PD is remarkably suppressed to 5.17 × 10⁻¹¹ A at a bias of 5 V. Importantly, the photocurrent of the corresponding device is still as high as 1.37 × 10⁻³ A, leading to a high photo-to-dark current ratio of 2.65 × 10⁷ and the capability to detect the UV light with the intensity below 10 nW cm⁻². Moreover, the H-doped a-Ga₂O₃ thin films have also been deposited on polyethylene naphtholate substrates to construct flexible UV PDs, which exhibit no great degradation in bending states and fatigue tests. These results demonstrate that hydrogen doping can effectively improve the performance of a-Ga₂O₃ UV PDs, further promoting its practical application in various areas.

Even in their bulk forms, complex alloys like high-entropy alloys (HEAs) exhibit favorable activity and stability as electrocatalysts for the oxygen evolution reaction (OER). However, the underlying reasons are not yet fully understood. In a family of Mo-doped CrFeCoNi-based HEAs, we have identified three crucial factors that govern their performance: (i) homogeneous solid solution phase of HEAs helps to maintain high-valence states of metals; (ii) surface reconstruction results in a hybrid material comprising amorphous domains and percolated crystalline structures; (iii) diversity of active intermediate species (M–O, M–OOH, and, notably, the abundance of superoxide μ–OO), which display stronger adsorption capacity on the reconstructed surface. These results are revealing due to their resemblance to findings in other families of electrocatalysts for OER, as well as their unique features specific to HEAs. In line with these factors, a CrFeCoNiMo0.2 bulk integrated electrode displays a low overpotential of 215 mV, rapid kinetics, and long-term stability of over 90 d. Bulk HEAs hold great potential for industrial applications.

Antibacterial activity and mechanical properties of FeCoCr-Ag medium entropy alloys were studied via combinatorial fabrication paired with high-throughput characterizations. It was found that the antibacterial activity and mechanical properties exhibit non-linear dependence on the content of Ag addition. Within the studied alloys, (FeCoCr)₈₀Ag₂₀ possesses an optimized combination of different properties for potential applications as antibacterial coating materials. The underlying mechanism is ascribed to the formation of a dual-phase structure that leads to competition between the role of Ag phase and FeCoCr phase at different Ag content. The results not only demonstrate the power and effectiveness of combinatorial methods in multi-parameter optimization but also indicate the potential of high entropy alloys as antibacterial materials.

Glasses have long been considered as frozen liquids because of the similarity between their static amorphous structures. While the modern theories about glass transition suggest that glass transition may result from supercooling of a heterogeneous liquid that contains fast and slow regions, it remains unclear whether such a physical picture applies to metallic glasses, which are a densely packed solid glass that was once believed to be a vitrified homogeneous metallic liquid. However, in the recent work published in Nature Materials, Chang et al provide compelling evidence to show that metallic glasses contain liquid-like atoms that behave as a high-temperature liquid in stress relaxation. Being activated under cyclic loading, this quenched-in liquid results in a fast relaxation process, which is discovered in a variety of metallic glasses. Their results are important and deliver a strong message that metallic glasses have a dynamic microstructure containing liquid- and solid-like atoms. Most importantly, the outcome of their research provides physical insight into the nature of glass-transition in metallic glasses, and also helps unravel their structure-property relations.

Advanced high-strength steels are key structural materials for the development of next-generation energy-efficient and environmentally friendly vehicles. Medium Mn steel, as one of the latest generation advanced high-strength steels, has attracted tremendous attentions over the past decade due to its excellent mechanical properties. Here, the state-of-the-art developments of medium Mn steel are systematically reviewed with focus on the following crucial aspects: (a) the alloy design strategies; (b) the thermomechanical processing routes for the optimizations of microstructure and mechanical properties; (c) the fracture mechanisms and toughening strategies; (d) the hydrogen embrittlement mechanisms and improvement strategies.

High-entropy alloys (HEAs) are emerging materials that are developed based on entropy, and draw significant attention for the potential to design their chemical disorder to bring out different structural and physical characteristics. Over the past two decades, significant salient efforts have been conducted to explore many unique and useful properties of HEAs, such as overcoming the strength–ductility trade-off, outstanding thermal stability, and excellent low temperature plasticity. Here, we review the key research topic of HEAs in the following three aspects: (a) performance advantages and composition design, (b) performance-driven HEAs and (c) fabrication process-driven HEAs. Towards their industrial applications, our article reviews a large range of methods to synthesise, fabricate and process HEAs. We also discuss the current challenges and future opportunities, mainly focusing on performance breakthroughs in HEAs.