High-entropy alloys (HEAs) have attracted considerable attention because of their exceptional mechanical, corrosion, and oxidation resistance. However, their reliance on high-purity elemental metals results in high raw-material costs, substantial energy consumption, and considerable environmental burdens, which restrict their large-scale industrial application. In this context, low-cost feedstocks offer promising alternatives for developing more sustainable HEA manufacturing routes. Nevertheless, the use of these feedstocks inevitably introduces impurity elements together with pre-existing non-metallic inclusions. These impurities can alter inclusion formation and evolution, promote segregation and secondary-phase formation, and ultimately deteriorate the mechanical and functional properties of HEAs. This review systematically summarizes recent progress in the green and low-cost production of HEAs, with particular emphasis on the impurity evolution, non-metallic inclusion formation and removal, and refining strategies. The advantages and limitations of various manufacturing methods are critically discussed. Vacuum induction melting provides an effective basis for reducing gaseous impurities and homogenizing recycled feedstocks, whereas slag refining can facilitate the removal of oxygen-, sulfur-, and nitrogen-related impurities and non-metallic inclusions. Oxidative gas treatment, such as CO 2 -containing gas blowing, provides a complementary approach for removing metallic impurities, particularly Al, Si, and P, which are difficult to eliminate under conventional vacuum conditions. The combination of vacuum melting, slag refining, suitable refractory selection, and controlled oxidative treatment therefore represents a promising strategy for achieving comprehensive impurity control. Furthermore, the review highlights that the cleanliness of recycled-material-derived HEAs is governed by the coupled effects of feedstock chemistry, thermodynamics, reaction kinetics, inclusion characteristics, melt properties, slag–metal interactions, refractory materials, and solidification behavior. Future research should focus on establishing quantitative impurity tolerance limits and optimizing integrated refining processes, which are essential for establishing scalable, cost-effective, and environmentally sustainable pathways toward the industrial production of high-cleanliness HEAs.
Mechanical alloying is a key method for producing nanostructured metals, alloys, and composites with enhanced properties. The discrete element method (DEM) has become a powerful process-scale tool for resolving media motion, collisions, energy transfer, and particle–wall interactions. However, conventional DEM does not directly predict powder breakage, permanent deformation, cold welding, defect generation, chemical mixing, or phase evolution. These outcomes require calibrated breakage, constitutive, thermal, or multiscale material-response models. This review critically assesses DEM frameworks and complementary finite-element, atomistic, kinetic Monte Carlo, first-principles, and thermodynamic approaches that connect mill-scale loading to materials-science outcomes. DEM-only formulations and their coupling with population balance models, probability-based breakage models, and sub-DEM methods are examined in terms of their capabilities, limitations, required parameters, and experimental validation. These extensions use DEM-derived stressing statistics to estimate particle-size evolution, fracture, deformation, and accumulated strain beyond the short times directly simulated. Couplings with computational fluid dynamics and smoothed particle hydrodynamics are evaluated for wet milling, where fluid–particle interactions modify media motion, energy dissipation, and breakage. Thermal models are also reviewed, including frictional heat generation, contact conduction, environmental heat transfer, and behavior relevant to cryomilling. Particular attention is also given to calibration and validation of DEM parameters, including restitution, friction, breakage, and material constants. Finally, key challenges are identified in scaling DEM to industrial timeframes, integrating multiscale models, and bridging predictions with experiments, thereby offering a roadmap for more predictive materials processing.
Laser powder bed fusion (LPBF) enables the fabrication of aluminum matrix particulate composites (AMPCs) with opportunities for microstructural refinement and precipitation strengthening. However, reported mechanical responses remain highly non-monotonic with respect to particle content. Strength improvements are often accompanied by limited or inconsistent gains in ductility, fatigue performance, and damage tolerance. This review adopts a constraint-first perspective and organizes the literature along a processing-linked constraint pathway. The performance of LPBF-processed AMPCs is interpreted in terms of a hierarchy of coupled physical constraints that become active at different stages. These include processing stability associated with melting behavior, interfacial mechanical and chemical compatibility under rapid thermal cycling, particle redistribution during melt-pool transport and solidification, and the transition of crack initiation control among competing defect populations. Evidence is synthesized across the full processing chain, from energy coupling at the powder bed to melt-pool dynamics, particle redistribution, and defect evolution. This framework helps explain why particle additions lead to improved mechanical performance in some cases, but not in others where processing-induced constraints become dominant. Based on this synthesis, a transferable design framework is proposed. It emphasizes stable processing conditions, interface states that sustain load transfer, control of particle clustering, and performance evaluation based on defect severity rather than average properties. Overall, this review frames LPBF-processed AMPCs as a constraint-governed system, and provides a basis for interpreting scattered results and improving cross-study comparability.
The need for sustainable energy has become paramount in today's context, owing to the alarming rise in global greenhouse gas emissions and the consequent adverse impact on climate change. Among these energy resources, nuclear energy holds a special place in fulfilling global commitments and thus warrants a special interest. Zirconium alloys are the preferred in-core structural materials in water-cooled reactors, the most widely used reactor configuration. Nevertheless, further research is needed to improve the understanding of how structural materials influence the long-term and reliable performance of nuclear reactors. Material performance and in-reactor degradation mechanisms are largely governed by various metallurgical factors that can be engineered during thermo-mechanical processing (TMP). The structural evolution at each TMP step governs that of the following steps, so that the final microstructure and properties are a cumulative outcome of the processing steps. Despite the criticality, the interlinkage among processing, microstructure, texture, and properties has not been comprehensively reviewed and remains scattered in the literature. This article provides an in-depth, state-of-the-art review of the interlinkages between processing, microstructure, and properties in zirconium alloys, elucidating the foundation of physical metallurgy, the critical role of TMP in microstructure and texture control, and the impact of microstructure and texture on the key properties of zirconium alloys. In summary, by focusing on the complex interdependence of processing, microstructure, and properties in zirconium alloys, this review emphasises their importance in advancing nuclear reactor technology and highlights emerging opportunities for innovation. Future research integrating novel alloy compositions, advanced characterisation techniques, and predictive modelling will be essential for improving the durability, safety, and reliability of zirconium-based structural materials, thereby supporting a more sustainable nuclear energy ecosystem.
Hydrophobic materials have become increasingly important for separation technologies operating under humid or chemically aggressive conditions, where conventional membranes often suffer from performance degradation. This review summarizes recent advances in hydrophobic membranes based on fluoropolymers, graphitic materials, zeolites, and porous crystalline frameworks, including metal–organic frameworks (MOFs), covalent organic frameworks (COFs), and hydrogen-bonded organic frameworks (HOFs). The roles of surface hydrophobicity, pore structure, and interfacial interactions in controlling transport, selectivity, and stability are critically discussed across applications in water treatment, organic solvent nanofiltration, gas separation, air purification, and energy-related systems. Representative examples highlight how hydrophobic interfaces mitigate water-induced swelling, pore blocking, and competitive adsorption, thereby enabling stable and efficient separations. Despite substantial progress, challenges remain in scalable fabrication, long-term stability, and cost-effective production, particularly for framework-based membranes. Future directions toward hybrid architectures, defect and interface engineering, and scalable processing are outlined to facilitate the translation of hydrophobic membrane materials into industrially relevant separation technologies.
