Microwave absorbing materials（MAM），as a crucial component of radar stealth technology，reduce the radar cross-section of detected targets by absorbing radar waves，thereby lowering the probability of detection. Currently widely applied in the stealth design of various aircraft，naval vessels，and armored vehicles，they effectively enhance equipment survivability and combat effectiveness on the battlefield，making them strategic key materials in the defense sector. Therefore，developing high-performance radar-absorbing materials represents both a research hotspot in advanced materials science and a critical requirement for national defense security. This paper first provides a detailed discussion on the definition，classification，and absorption principles of radar-absorbing materials. It then systematically summarizes the current research status and latest advancements across different types of radar-absorbing materials，analyzing their respective advantages and limitations based on practical application contexts. Finally，focusing on key challenges in the field，it identifies some primary future research directions： deepening the understanding of loss mechanisms，developing novel materials with unique electromagnetic responses，and enhancing engineering design capabilities.

Refractory high-entropy alloys （RHEAs）， owing to their exceptional high-temperature properties， show great potential for use in extreme environments such as aerospace systems. However， the inherent complexity of their multicomponent systems poses significant challenges to the efficiency of conventional alloy design methods. Although additive manufacturing （AM） overcomes some limitations of traditional fabrication routes， its intrinsic non-equilibrium solidification behavior and complex process-parameter space introduce new challenges in microstructural control and property optimization. In this context， machine learning （ML） offers a data-driven paradigm for uncovering the intricate composition-structure-property relationships in RHEAs and provides a powerful tool for intelligent materials design. This review systematically summarizes the latest advances in the application of ML to RHEAs， with particular focus on key issues in AM scenarios. On the one hand， the roles of ML in phase prediction， strength and ductility optimization， and hardness design are discussed. On the other hand， ML-enabled strategies for process-parameter optimization， defect mitigation， and microstructural tailoring in AM are thoroughly analyzed. Despite notable progress， several challenges remain， including the scarcity of AM-specific datasets， the limited generalization capability of process-property models， and the insufficient integration of physical mechanisms. Therefore， establishing standardized databases oriented toward additive manufacturing， developing machine learning models integrated with physical constraints， and constructing an integrated process-microstructure-property optimization framework are key directions for promoting the transition of refractory high-entropy alloys in the field of additive manufacturing from “printable” to “designable”.

Mg-air batteries have garnered significant attention in recent years due to their outstanding advantages， including high theoretical energy density， excellent safety， low cost， and environmental friendliness. However， systematic reviews concerning aqueous Mg-air battery electrolytes remain relatively scarce. The Mg anode is prone to self-corrosion， discharge product accumulation， and severe block effect in aqueous environments. This results in low anode utilisation， suboptimal operating voltages， and pronounced voltage fluctuations， making the electrolyte a critical factor constraining the practical application of Mg-air batteries. To address this， this paper systematically reviews the fundamental properties and key influencing factors of aqueous Mg-air electrolytes， focusing on electrolyte system selection， interfacial control strategies， and additive mechanisms. The review covers the structural characteristics and applicability of chlorinated and chlorine-free near-neutral electrolytes， the regulatory roles of inorganic， organic， and composite additives， and the synergistic effects of anions at the electrolyte/anode interface. Finally， future development directions for aqueous Mg-air electrolytes are proposed， including in-depth understanding of interfacial regulation mechanisms， green design of electrolyte systems， and rapid formulation screening based on machine learning. This paper aims to provide reference for the research and application of high-performance Mg-air battery electrolytes.

MgH₂ has become one of the most widely studied hydrogen storage materials due to its high theoretical hydrogen storage capacity， improved safety， and reversibility. However， its application is limited by its high thermodynamic stability and poor kinetic performance. A doping catalyst can effectively reduce the reaction barrier of hydrogen absorption and desorption， thereby accelerating the reaction rate of hydrogenation and dehydrogenation in the Mg-H system. This approach is an effective and simple method to enhance the hydrogen storage performance of MgH₂. Transition metals and their oxides have been widely studied because of their excellent catalytic properties. In this review， various types of transition metals and their oxide catalysts are introduced， and their effects on the hydrogenation and dehydrogenation of MgH₂ and the catalytic principle are briefly described. Finally， it is concluded that doping with multi-element alloys， multi-component metal oxides， or combinations of metals and metal oxides to utilize the synergistic effects between different metals is an important method for improving catalytic performance. However， the catalytic mechanisms of some transition metals and their oxides remain unclear at present. Deepening the understanding of catalytic mechanisms， especially conducting in-depth investigations at the atomic scale， will provide strong support for the development and application of magnesium-based hydrogen storage materials with better hydrogen storage performance.

Organic liquid electrolytes commonly used in commercial lithium-ion batteries pose potential safety hazards， such as flammability and electrolyte leakage. In comparison， solid-state lithium-ion batteries based on solid polymer electrolytes have attracted extensive attention， due to their high safety and high energy density. In this article， we introduce the structure and ion conduction mechanism of solid polymer electrolytes， especially three modes of polymer segment migration， surface diffusion， and ion hopping. In terms of preparation methods， the principles， preparation processes， and advantages and disadvantages of ex-situ curing and in-situ polymerization curing are analyzed in detail. The ex-situ curing method has a mature process， but there are a few issues， such as poor interface contact and high thickness. The in-situ curing method can achieve excellent interface compatibility and is also compatible with current battery assembly technology. To overcome the problems of low room temperature ionic conductivity and insufficient electrochemical stability of solid polymer electrolytes， various modification strategies， such as polymer molecular structure design， plasticizer addition， polymer blending， nanoparticle filling， and multi-layer design are explored. These strategies aim to reduce polymer crystallinity， construct fast ion channels， anchor anions， and optimize the interface between electrolytes and electrodes. Finally， the review points out the development trend of solid polymer electrolytes in large-scale preparation and application in solid-state batteries， providing references for future research.

Carbon fiber reinforced thermoplastic composites （CFRTP） show great application potential in aerospace and other fields owing to their advantages of light weight， high specific strength， rapid prototyping， and weldability. As a commonly used lightweight metal in the aerospace industry， titanium alloy is a material that can be directly bonded to CFRTP without corrosion defects. Achieving high-performance joining between the two is of great significance for reducing structural weight， cutting carbon emissions， and ensuring the operational safety of equipment. However， due to the differences in their physical and chemical properties， joining the two materials poses numerous challenges. This paper reviews the research progress on the welding of CFRTP and titanium alloy. It summarizes and analyses the process characteristics of various welding technologies， surface treatment methods of titanium alloys， and interface joining mechanisms. Furthermore， it looks forward to the common issues that need to be addressed in the welding of CFRTP and titanium alloys， aiming to provide a reference for the large-scale assembly application of CFRTP/titanium alloy hybrid structure.

Titanium alloys are universally recognized as the prime option for core load-bearing structures in aero-engines， owing to their remarkable blend of high strength， low density， exceptional creep resistance， and outstanding corrosion resistance. The reliability of titanium alloy joints has a direct bearing on the operational safety and service life of aero-engines. Linear friction welding （LFW）， an efficient solid-state joining technique that is precisely tailored to the precision manufacturing requirements of aero-engines， offers substantial benefits such as near-net shaping， minimal welding flaws， and excellent joint integrity. It facilitates the high-quality and consistent bonding of titanium alloy components and plays a pivotal role in the fabrication and repair of complex， integrated components like blisks.This paper centers on the research and application demands of LFW technology for aero-engine components. It provides an in-depth review of the progress in titanium alloy LFW across four key areas： process experimentation， physical simulation， finite element numerical modeling， and post-weld heat treatment. It systematically summarizes the current research status and identifies the existing challenges in each field. Moreover， the paper points out future research directions， including the evaluation of long-term service performance， multi-scale numerical simulations ranging from the microstructural to the macroscopic level， and the optimization of modified LFW process parameters. These efforts are crucial for promoting the wider industrial application of titanium alloy LFW technology.

Particle-reinforced aluminum matrix composites （PRAMCs）， as light-weight and high-performance structural and functional materials， offer broad application prospects in aerospace， weaponry， transportation， and other fields. This paper systematically reviews the main preparation technologies for PRAMCs developed both domestically and internationally， providing a comparative analysis of two major categories of preparation methods， ex-situ and in-situ synthesis， in terms of their process flows， raw materials， microstructural characteristics， and resulting properties， along with their respective technical advantages and limitations. To further achieve the high-quality forming of high-performance PRAMCs components， semi-solid thixoforming technology effectively integrates the near-net-shape advantages of casting and the mechanical performance benefits of plastic forming， compared to traditional casting and plastic processing techniques. It demonstrates significant potential for the near-net-shape forming of complex-shaped， high-performance PRAMCs components. The key prerequisite for semi-solid thixoforming lies in the preparation of semi-solid billets with fine and uniform spherical microstructures. Thus， this paper provides a detailed overview of the primary methods for preparing semi-solid billets， and reviews research progress in related thixoforming technologies for composites and alloys. Finally， future trends for PRAMCs are discussed， focusing on design and development， innovation in preparation processes， and the deepened application of thixoforming technology.

Fused filament fabrication （FFF） technology boasts significant advantages， including high design flexibility， mold-free operation， and the capacity to rapidly construct complex structures， making it a key method for 3D printing of continuous carbon fiber reinforced thermoplastic polymer （CCFRTP）. However， during the actual printing， CCFRTP often experiences a decline in mechanical properties due to insufficient interfacial bonding between the thermoplastic matrix and the continuous carbon fiber reinforcement， as well as a high internal porosity. To address this issue， this paper analyzes two major factors influencing the performance—the resin matrix and the carbon fiber reinforcement. Based on this， it reviews the recent advances in FFF technology， examines the effects of various printing parameters on mechanical properties， along with optimization strategies. Finally， future development directions and application prospects are discussed.

Fiber-reinforced composites，renowned for their high specific strength，high specific modulus，exceptional fatigue resistance，and outstanding corrosion resistance，are extensively utilized across the aerospace，transportation，and energy industries. Nevertheless，under severe service conditions，the latent progression of internal damage can precipitate sudden failure，underscoring the pressing need for effective structural health monitoring （SHM） technologies. This review comprehensively summarizes the latest advancements in this field，conducting a systematic analysis of the principles，performance merits，and principal limitations of both offline nondestructive testing methods （encompassing ultrasound，X-ray/CT，infrared thermography，and acoustic emission） and online monitoring techniques （including surface-mounted strain gauges，piezoelectric and fiber-optic sensors，as well as embedded optical fiber，resistive，and piezoelectric sensors）. Comparative analysis reveals that offline techniques boast high accuracy but are devoid of real-time capability，while online techniques facilitate dynamic monitoring yet are hampered by limited penetration depth and signal interpretation capabilities. Finally，the paper delineates key avenues for future development，such as the co-design of sensors and structures，multifunctional damage sensing，and intelligent signal processing for pattern recognition and predictive maintenance，offering a valuable reference for the intelligent monitoring of composites under complex service conditions.