Metallic glasses (MGs) that mainly made up of metallic elements are a new member of the glassy materials family. This new kind of glass combines the characteristics of liquids and solids, glasses and metals, making it fascinating to both scientists and industrialists. With the discovery of more and more systems, MG is becoming one of the most active research field in metallic materials, and some concepts and technologies derived from MGs also facilitate the development of other materials from quasi-crystals to high entropy alloys. MGs have now been successfully used in aerospace, robotics, medicine, consumer electronics, etc. and the practical applications of MGs are still growing. On the other hand, the diverse properties and the unique structure of the MGs render them ideal models to study major open issues including the structural model of disordered materials, glass transition, collective motion and energy landscape. However, understanding the emerging properties and phenomena of MGs still poses enormous challenges, which has stimulated a wealth of efforts, including the development of new experimental approaches, the synthesis of systems with tailored properties, and the advancements in experimental techniques, theoretical models, and numerical simulations. In this Roadmap, we try to provide a broad overview of recent and potential future activities in the MG field, and present a roadmap for the development and applications of MGs by gathering contributions form scientists with diverse backgrounds, illustrating the major challenges and discussing the latest technology and strategy to tackle these challenges with experts covering various developments in general concepts, synthesis and characterisation, and theoretical and simulation methods.

Nanocrystallization of glasses is a critical pathway for designing advanced materials with superior properties. In this study, we investigated the crystallization behavior of lunar glasses retrieved by the Chang’E-5 mission. It was observed that solar wind irradiation induces abundant Fe nano-clusters with a size of about 2 nm within a layer of about 4 µm close to the surface. Upon heating, these defects act as nucleation sites, facilitating the precipitation of homogeneous and dense Fe nanocrystals. In contrast, the uni-rradiated interior of the lunar glass crystallizes into coarse Fe crystals. Inspired by these findings, advanced magnetic nanocrystalline alloys are designed based on Fe86B14 metallic glass by H+ ion irradiation. After H+ ion irradiation and nanocrystallization, the size of nanocrystals close to the surface is about 5–8 nm, which is much smaller than the nanocrystals in the deep interior (15–20 nm). The permeability at 10 kHz increases by about 10.2

Agglutinate particles, an important component resulting from micrometeoroids impacts, account for about 13.4% to 84.7% of the volume of lunar regolith depending on its maturity. They are crucial in the soil's evolution and the migration of volatile substances. Here, we examined a representative agglutinate particle from Chang'e-5 samples and modeled how volatiles move through its porous framework. Our analysis revealed that the agglutinate's surface features a patchy distribution of smooth, open pores, as shown by both surface and 3-dimensional structural assessments. By integrating elemental distribution data, we propose that the formation of these smooth, open pores is primarily due to the flow of gaseous volatiles, byproducts of intricate physiochemical reactions occurring in the lunar surface layer during impacts by micrometeoroids. Numerical models of volatile transport in the porous agglutinate have been developed for different flow regimes. These models demonstrate that under the intense conditions of impacts, the transport of volatiles occurs at a remarkably high velocity. Consequently, it is improbable that water would accumulate within the porous structure of lunar soil agglutinates. Nevertheless, understanding this process is valuable for gaining a deeper understanding of the lunar regolith's development and for potential future endeavors in extracting water from the lunar surface.

Finding water resources is a crucial objective of lunar missions. However, both hydroxyl (OH) and natural water (H2O) have been reported to be scarce on the Moon. We propose a potential method for obtaining water on the Moon through H2O formation via endogenous reactions in lunar regolith (LR), specifically through the reaction FeO/Fe2O3 + H -> Fe + H2O. This process is demonstrated using LR samples brought back by the Chang'E-5 mission. FeO and Fe2O3 are lunar minerals containing Fe oxides. Hydrogen (H) retained in lunar minerals from the solar wind can be used to produce water. The results of this study reveal that 51-76 mg of H2O can be generated from 1 g of LR after melting at temperatures above 1,200 K. This amount is similar to 10,000 times the naturally occurring OH and H2O on the Moon. Among the five primary minerals in LR returned by the Chang'E-5 mission, FeTiO3 ilmenite contains the highest amount of H, owing to its unique lattice structure with sub-nanometer tunnels. For the first time, in situ heating experiments using a transmission electron microscope reveal the concurrent formation of Fe crystals and H2O bubbles. Electron irradiation promotes the endogenous redox reaction, which is helpful for understanding the distribution of OH on the Moon. Our findings suggest that the hydrogen retained in LR is a significant resource for obtaining H2O on the Moon, which is helpful for establishing a scientific research station on the Moon.

Melting and solidification of lunar regolith are pivotal for comprehending the evolutionary dynamics of lunar volcanism, geology, and impact history. Additionally, insights gained from these processes can contribute to the advancement of in situ resource utilization technologies, for instance additive manufacturing and resource extraction systems. Herein, we conduct the direct observation of the melting and rapid solidification of lunar particles returned by the Chang’E 5 mission. The melting temperature and melting sequence were obtained. Bubble generation, growth, and release were clearly observed, with a maximum bubble diameter of 5 µm, which is supposed to be according to the release of volatiles that embedded in the particles. During the solidification process, evident crystallization occurred with incremental crystal growth rate approximately of 27 nm/s. Scanning electron microscopy and energy-dispersive x-ray spectroscopy results verified that the Fe-rich mineral crystalizes first. These results would improve the understanding of the evolution of lunar volcanism, geology, and impact history.

Lunar glasses with different origins act as snapshots of their formation processes, providing a rich archive of the Moon's formation and evolution. Here, we reveal diverse glasses from Chang'E-5 (CE-5) lunar regolith, and clarify their physical origins of liquid quenching, vapor deposition and irradiation damage respectively. The series of quenched glasses, including rotation-featured particles, vesicular agglutinates and adhered melts, record multiple-scale impact events. Abundant micro-impact products, like micron- to nano-scale glass droplets or craters, highlight that the regolith is heavily reworked by frequent micrometeorite bombardment. Distinct from Apollo samples, the indigenous ultra-elongated glass fibers drawn from viscous melts and the widespread ultra-thin deposited amorphous rims without nanophase iron particles both indicate a relatively gentle impact environment at the CE-5 landing site. The clarification of multitype CE-5 glasses also provides a catalogue of diverse lunar glasses, meaning that more of the Moon's mysteries, recorded in glasses, could be deciphered in future.

Abstract Volatiles transport in the lunar regolith is essential for lunar soil evolution and in-situ resources utilization (ISRU) and has not been fully understood. Here, we characterize a typical agglutinate particle from Chang’E-5 samples and demonstrate the transport behavior of volatiles through the porous structure. The results of surface and 3D structural characterization indicate that the formation of the smooth porous structure is mainly caused by volatiles flow. Based on the element distribution analysis, we further speculate the main component of the volatiles is gas water attributed to the reduction of FeO by abundant hydrogen in the superficial lunar regolith during micrometeoroids impacts. Numerical models of volatiles (gas water) transport in the porous agglutinate have been developed for different pressure conditions. The results show the ultrafast transport of volatiles makes the superficial regolith dry and barren under high-vacuum condition. We conclude that rapid escape of volatiles can hardly retain water in the superficial lunar soil yet provides opportunities for development of ISRU technology.

Teleoperation robots remain superior to fully automated robots in complicated and unstructured environments (e.g., in-orbit assembly). However, the collision risk is also greatly increased in these environments. Therefore, the teleoperation robot should possess the capability of collision risk perception and be configured with security assistance strategy to improve safety and efficiency. With this objective in mind, this paper proposes a collision risk assessment system based on fuzzy theory, which comprehensively considers the effects of shortest distance, operation speed, and delay time. The introduction of fuzzy theory makes the risk assessment results more accurate. Furthermore, this paper also proposes a creative discrete expandable bounding box method to make the calculation of the nearest distance between complicated obstacles and the robot more efficient and faster. Secondly, to improve the safety and efficiency of teleoperation, this paper proposes a set of teleoperation assistance strategies for teleoperation robots based on collision risk. The strategies include partial view highlighting, variation in the motion mapping ratio, and haptic risk warning, all of which are achieved in the graphical interactive interface. Finally, this paper verifies the proposed collision risk model and the operation assistant strategy through experiments. The results show that the proposed fuzzy collision risk model has a correct trend with risk factors, and the proposed operation assistance strategies can effectively reduce the robot collision risk and improve the safety of teleoperation robots. In conclusion, this research contributes to the collision risk assessment and obstacle avoidance assistance strategy of teleoperation robots.

在轨制造技术在深空探测领域有广泛的应用前景，是各航天大国竞相发展的先进技术。目前，非金属材料的在轨制造已经实现，而金属材料在轨制造仍面临很多困难。文章介绍了国内外在轨制造技术的发展现状，着重介绍欧洲和美国金属材料在轨制造的技术路径，分析了发展金属材料在轨制造技术面临的困境和难点。针对这些难点，提出利用非晶合金材料的热塑性加工特性来实现金属材料在轨制造技术的突破，对有望应用于在轨制造的基于非晶合金的制造技术进行介绍，并对其未来发展方向进行探讨，以期为金属材料在轨制造技术的发展提供参考。

In‐space manufacturing draws great attentions due to its potential applications in space exploration. However, the high‐vacuum and microgravity environment introduces extrascientific and technical challenges. Biological experiments in the International Space Station show that spiders can build webs under microgravity conditions, which indicates that the spiderweb building could be independent of gravity. Herein, inspired by the spiderweb, a strategy for additive manufacturing in space, that is, building a 3D structure composed of metallic ribbons and bonded joints, is proposed. Several kinds of 3D metallic structures are manufactured and the flexibility and strength of the obtained jointed‐ribbons are tested. It is showed in the results that the tensile strength of the 3D metallic structures reaches about 70% of that of the raw materials, while their hardness almost keeps unchanged. Herein, an effective method to realize the manufacturing of the complex metallic structures in space is provided.

Physical aging is a long-lasting research hot spot in the glass community, yet its long-term effects remain unclear because of the limited experimental time. In this study, we discover the extraordinary aging effects in five typical lunar glassy particles with diameters ranging from about 20 to 53 micrometers selected from Chang’e-5 lunar regolith. It is found that geological time scales’ aging can lead to unusually huge modulus enhancements larger than 73.5% while much weaker effects on hardness (i.e., varies decoupling evolutions of Young’s modulus and hardness during aging) in these lunar glassy samples. Such extraordinary aging effects are primarily attributed to the natural selected complex glassy compositions and structures, consistent with high entropy and minor element doping criteria, prevailing under the special lunar conditions and the extensive aging time for the lunar glasses. This study offers valuable insights for developing high-performance and stable glassy materials for radiation protection and advanced space explorations.

The present study designs and prepares amorphous Zr x (Al0.25Ni0.25Cu0.5)100- x (at.%) alloys system by copper mold casting. The effect of Zr content on the glass-forming ability (GFA) was measured through X-ray diffractometer (XRD), thermal properties through differential scanning calorimeter (DSC), density through Archimedes drainage method, formability through the standard thermoplastic formability (TPF) test, and hardness through nanoindentation. A composition-dependent TPF ability of Zr x (Al0.25Ni0.25Cu0.5)100- x bulk metallic glasses (BMGs) as a function of x is found, exhibiting a non-monotonous behavior. The density and hardness are sensitive to the change of composition, exhibiting a monotonous behavior as a function of x in Zr x (Al0.25Ni0.25Cu0.5)100- x BMGs. In addition, we discuss the relationship between density, hardness and structure.

Metallic glasses (MGs), due to their exceptional properties resulting from the amorphous structures, may be potential candidates for space applications. However, the effect of space conditions on the stability of MGs is not clear, which should be taken into account for practical use. The present work assessed the thermal stabilities of MGs in the simulated space thermal fields under vacuum condition, with a specific focus on the cryogenic thermal cycling with a high ratio of the non-isothermal to isothermal durations and the cryogenic treatment for a long-duration. The dynamics and thermal properties of MGs under the simulated space conditions were found to be different than those in laboratory-based conditions. MGs with lower fragility values were also determined to show greater thermal stability. On this basis, rules for the selection of MGs to ensure thermal stability during future space applications were proposed. (c) 2022 Elsevier B.V. All rights reserved.

Self-healing with the capability to be self-adhesive, which can recover from physical damage, is essential for space applications. However, regulatable adhesion under extreme space conditions has only been realized in low-dimensional materials and still poses a challenge on the discovery of suitable materials. Under an ultrahigh vacuum of 10−7 Pa, we found a strong adhesion between bulk Cu46Zr46Al8 metallic glasses with a maximum adhesion strength of 32.8 kPa, which is two orders of magnitude higher than that of the corresponding crystalline. This adhesion is suggested to be induced by a liquid-like layer on a bulk metallic glass surface, which has a high diffusion coefficient of 6.9 × 10−11 m2⋅s−1, even at a relatively low temperature of 263 K. By investigating the dynamics for this liquid-like layer, a special fractional Stokes–Einstein relationship was found. Inspired by this strong adhesion, metallic glasses can be proposed as one of the promising self-healing materials for future space applications.

This paper presents an electric-pulse powered additive manufacturing (EPPAM) of metallic glass ribbons, which can be implemented under lower pressure. By this method, Fe73.5Cu1Nb3Si13.5B9 amorphous ribbons, 25 mu m thick, can be formed into various geometries. The formed samples were put to a series of tests and measurement, including X-ray diffraction, differential scanning calorimetry, and transmission electron microscopy. The results and analyses indicate that a good amorphous structure is retained and a high tensile strength is achieved in the bonding part. Without needing crucial atmospheric conditions, such as vacuum or inert gas, this EPPAM can be applied to 3D printing of special-shaped amorphous components, e.g., those used in electromagnetic shielding devices.

Helium-3 (3He) is a noble gas that has critical applications in scientific research and promising application potential as clean fusion energy. It is thought that the lunar regolith contains large amounts of helium, but it is challenging to extract because most helium atoms are reserved in defects of crystals or as solid solutions. Here, we find large amounts of helium bubbles in the glassy surface layer of ilmenite particles that were brought back by the Chang'E-5 mission. The special disordered atomic packing structure of glasses should be the critical factor for capturing the noble helium gas. The reserves in bubbles do not require heating to high temperatures to be extracted. Mechanical methods at ambient temperatures can easily break the bubbles. Our results provide insights into the mechanism of helium gathering on the moon and offer guidance on future in situ extraction.

This study focuses on the physical and chemical properties of surficial lunar regolith (LR) samples returned from the Moon by the Chang’E-5 (CE-5) mission. Insights regarding the effect of a new sampling geological site on the surficial lunar sample CE5C0400 were illustrated using nondestructive techniques such as laser diffractometry coupled with image analysis, X-ray computed tomography, and field emission scanning electron microscopy equipped with energy dispersive spectroscopy, and X-ray diffraction combined with Rietveld refinement. From the characterization analyses, the CE-5 sampling site in the northeastern Oceanus Procellarum on the Moon yields a unique collection of relatively regular-shaped and fine basalt-dominated particles. The median grain size D50 is (55.24±0.96) µm, falling within the relatively low end of the range of the Apollo lunar returned samples. The coefficient of uniformity Cu of 15.1 and the coefficient of curvature Cc of 1.7 could classify CE5C0400 to be well-graded. The minerals in CE5C0400 comprise approximately 44.5% pyroxene, 30.4% plagioclase, 3.6% olivine, and 6.0% ilmenite. There is a relatively low content of approximately 15.5% glass phase in the CE-5 lunar sample. From the results, we deduce that the CE-5 LR structure could have mainly resulted from micrometeoroid impacts to achieve such a high level of maturity.

Direct measurement of critical cooling rates has been challenging and only determined for a minute fraction of the reported metallic glass forming alloys. Here, we report a method that directly measures critical cooling rate of thin film metallic glass forming alloys in a combinatorial fashion. Based on a universal heating architecture using indirect laser heating and a microstructure analysis this method offers itself as a rapid screening technique to quantify glass forming ability. We use this method to identify glass forming alloys and study the composition effect on the critical cooling rate in the Al–Ni–Ge system where we identified Al 51 Ge 35 Ni 14 as the best glass forming composition with a critical cooling rate of 10 4 K/s.

Metallic glasses are perfect materials for preparing nanostructures by dealloying, but the obtained nanostructures are commonly of porous structures. Through the combination of chemical dealloying and ultrasonic vibration, ultrathin Cu&Ag bimetallic nanoporous membranes (NPMs) have been prepared from a Zr48Cu36Ag8Al8 MG ribbon. Furthermore, by introducing oxygen into the Zr48Cu36Ag8Al8 MG ribbon to change the mechanism of the dealloying process, nanoporous (Cu&Ag)@Ag core-shell alloy was synthesized by the one-pot chemical dealloying of Zr–Cu–Ag–Al–O amorphous/crystalline composite, which provides a new way to prepare metallic core–shell nanostructures by a one-pot method. The introducing of oxygen can enable the dissolution and redeposition of Cu, and tunes the Cu&Ag NPM into the nanoporous (Cu&Ag)@Ag core-shell alloy. The nanoporous (Cu&Ag)@Ag core-shell alloy exhibits better and robust antibacterial activity against E. Coli DH5α due to its better oxidation resistance caused by the Ag skin. The present work provides important insights into the tuning of nanostructures through simple dealloying.

A magnetic thermostat employing soft-ferromagnetic particles and a varying magnetic field has been developed to investigate a homogeneous granular gas system in microgravity. While the thermostat’s mechanism of creating homogeneous distribution of the particles was shown earlier, its characteristics have not been understood well due to limited access to a microgravity environment. Therefore, a parametric study by numerical simulation based on the discrete element method is carried out in this paper to evaluate effects of tunable parameters in the thermostat. The result shows the capability of the system and provides a wide range of options and improvements for future experiments. Moreover, it predicts that the thermostat allows variation of homogeneity and excitation level of the granular gas just by changing the magnetic parameters without using any mechanical means. In addition, the suggested improvement is experimentally implemented and evaluated in a drop tower test.