The performance of high-power laser-driven white lighting systems is constrained by non-radiative losses from crystallographic defects in color converters. Here, a flux-assisted spray pyrolysis strategy using NaF is developed to enhance crystallinity and suppress defects in LuAG:Ce films. Films with NaF contents of 0-2.0 wt% were synthesized and annealed at 1500 degrees C. With 1.0 wt% NaF, crystallinity reached 93.1% without secondary phases or changes in Ce3 + valence or oxygen-vacancy concentration. The optimized film delivered 2160.9 lm (+25%), lowered operating temperature by 38.8 degrees C under 36 W center dot mm(-2) blue-laser excitation, and increased thermal-quenching activation energy by 13.3% (0.299 eV). Durability tests showed only 9.1% luminous flux degradation after 3600 s at 35 W center dot mm(-2), with stable correlated color temperature and color rendering index. Mechanistic analysis indicates moderate NaF promotes defect-suppressed crystallization, whereas excessive flux degrades luminescence, providing a scalable route to high-performance garnet films for laser lighting.

ATI 718Plus alloy powders were prepared by vacuum induction melting gas atomization (VIGA) and plasma rotating electrode preparation (PREP) methods. Effects of direct aging (DA) and homogenization-solution-aging (HSA) heat treatment processes on microstructure and mechanical properties of the alloy prepared by laser additive manufacturing (LAM) utilizing various powders mentioned above were systematically studied. The LAM process parameters such as laser power and scanning speed were optimized by orthogonal experiment. The results indicate that the porosity of the samples fabricated with PREP powder is controlled below 0.05

Gas atomization, as one of the most widely adopted methods for producing metal powders, has been extensively applied in additive manufacturing due to its ability to generate powders with small particle sizes, high sphericity, and excellent flowability. This paper compares several novel gas atomization techniques for metallic melts, including close-coupled gas atomization (CCGA), laminar flow gas atomization (LFGA), and ultrasonic gas atomization (UGA), discussing their fundamental principles, technical features, and process optimization in terms of their advantages and limitations. Based on multi-scale numerical simulations and experimental validation, we summarizes the effects of atomizer design and process parameters—such as gas temperature, pressure, and melt temperature—on powder properties, and discusses the mechanisms behind typical defects such as hollow and satellite powders in gas atomization. Finally, the technical challenges in powder production and property enhancement via gas atomization are highlighted, along with proposed directions for process optimization and future technological trends.

Austenite-based lightweight steels are designed to develop local chemical inhomogeneities—suchas chemically ordered κ-carbide formation—to achieve superior mechanical performance. To modelthe structural transformation of these complex steels, we develop a flexible pairwise energy modelcoupled with lattice Monte Carlo (MC) simulations. Extensive MC simulations are conducted to in-vestigate the thermodynamic atomic structures of FeMnAlCSi alloys as a function of composition andtemperature. Our simulation results are in good quantitative agreement with reported experimentaldata, and provide new insights into phase decomposition, species segregation and site preferences,and chemical order-disorder transitions. The simulations further offer microscopic views of atomicsegregation phenomena, including the incorporation of interstitial carbon atoms at grain boundaries(GBs). We identify the primary mechanisms underlying Si-accelerated κ-carbide formation as: (i)repulsive Si–C and Si–Si interactions that globally exclude Si from the ordered κ-carbide phase,and (ii) rapid carbon diffusion and segregation to GBs, which locally supersaturate the boundaryregion and promote GB precipitation. The present approach—combining DFT-parameterized pairenergies with large-scale MC simulations—is computationally efficient, captures the essential ther-modynamics of multi-component systems with interstitials, and can be readily extended to a widerange of multi-principal element alloy systems with constant lattice structures.

Refractory multi-principal element alloys offer a promising pathway for developing structural materials with exceptional strength retention at elevated temperatures. In this work, the mechanical response of an equiatomic TiZrNb refractory medium-entropy alloy with a single body-centered cubic structure was systematically investigated over a wide range of temperature (293–1273 K) and strain rate (0.001–3000 s−1), with particular emphasis on their coupling effects on deformation behavior. The alloy shows a good strength-ductility combination over the investigated range of temperatures and strain rates. Anomalous temperature dependence characterized by a distinct stress peak was observed at selected strain rates. Notably, the stress peak shifted toward higher temperatures as strain rate increases, which is defined as third-type strain aging. Microstructural analyses revealed that plastic deformation is governed by dislocation-mediated mechanisms, including pronounced lattice distortion, kink band formation, dynamic recrystallization at elevated temperatures, and the third-type strain aging induced by in-situ pinning of mobile dislocations by solute atmospheres or short-range clusters. Kink bands constitute a dominant intragranular deformation feature and enable effective strain accommodation across most deformation conditions. Finally, a deformation mechanism map is established to summarize the dominant mode spanning wide temperature and strain rate ranges. This study provides insights into the deformation physics of refractory multi-principal element alloys relevant to extreme thermo-mechanical applications.

The thermal expansion mismatch between sapphire and Ti-6Al-4V (TC4) alloy has traditionally limited the shear strength of ceramic-metal joints to <= 170 MPa. In this study, active brazing with Ag-35.25Cu-1.75Ti (wt%) leads to the formation of a dual-function microstructure, wherein uniformly dispersed submicron Ti3(Cu,Al)3O particles embedded in a ductile Ag-Cu matrix contribute to both Orowan strengthening and reduction in the coefficient of thermal expansion (CTE). Simultaneously, a thin Ti3(Cu,Al)3O reaction layer forms a coherent interface with sapphire. This tailored microstructure results in an unprecedented shear strength of 218.3 MPa, marking a 29% improvement over previous records. By combining fine-particle reinforcement, a coherent reaction layer, and mitigation of residual stresses, this approach offers a promising strategy for developing high-strength ceramic-metal joints. (sic)(sic)(sic)(sic)Ti-6Al-4V(TC4)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(CTE)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)170 MPa.(sic)(sic)(sic)(sic)(sic)Ag-35.25Cu-1.75Ti (wt%)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic):(sic)(sic)(sic)(sic)Ti3(Cu,Al)3O(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)Ag-Cu(sic)(sic)(sic),(sic)(sic)(sic)Orowan(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)CTE; (sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)Ti3(Cu,Al)3O(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)218.3 MPa,(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)29%.(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)/(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

ABSTRACT The thermal expansion mismatch between sapphire and Ti‐6Al‐4V (TC4) alloy has traditionally limited the shear strength of ceramic‐metal joints to ≤ 170 MPa. In this study, active brazing with Ag‐35.25Cu‐1.75Ti (wt%) leads to the formation of a dual‐function microstructure, wherein uniformly dispersed submicron Ti 3 (Cu,Al) 3 O particles embedded in a ductile Ag‐Cu matrix contribute to both Orowan strengthening and reduction in the coefficient of thermal expansion (CTE). Simultaneously, a thin Ti 3 (Cu,Al) 3 O reaction layer forms a coherent interface with sapphire. This tailored microstructure results in an unprecedented shear strength of 218.3 MPa, marking a 29% improvement over previous records. By combining fine‐particle reinforcement, a coherent reaction layer, and mitigation of residual stresses, this approach offers a promising strategy for developing high‐strength ceramic‐metal joints.

L10-FePt nanoparticles (NPs) are urgently anticipated because of their promising applications. However, the preparation of the NPs with both of high ordering degree and super-fine size is still a challenge. Inspired by recent studies on the effect of vacancy defects on structural ordering, we proposed an intentional vacancy defect design strategy for directly synthesizing highly ordered FePt NPs. In the present work, we used the first-principle calculations to investigate the influence of doping typical elements (Cu, Ag, and Pb) on the vacancy formation energy (Evac) of FePt NPs. The vacancy defects were effectively formed by introducing elements of larger atomic radii and higher propensity for segregation into the FePt lattice, facilitating the diffusion of Fe and Pt atoms. The Pb doping showed remarkable efficacy in promoting the ordering transition. Experimentally, wet-chemical synthesis confirmed the success of the proposed strategy in achieving highly ordered L10-FePt NPs with exceptional magnetic properties and super-fine size (ordering degree of 0.896, impressive coercivity of 21.74 kOe, and small particle size of 9.02 nm). Additionally, we have deduced a diffusion model elucidating the formation process of the ordered FePt NPs, focusing on the migration of Pb atoms from the center to the surface of the particles. This migration is demonstrated to generate more vacancies and promote the transition to the ordered L10-FePt phase. The findings of this research offer valuable insights into synthesizing highly ordered and ultrafine L10-type nanomaterials.

The physical property differences of gas atomized metal powders, such as particle size distribution (PSD), sphericity, etc., significantly affect the powder flowability, which may, in turn, interfere with the stability of Laser Powder Bed Fusion (LPBF) process and the consistency of printed part batches. Although the correlation between powder properties and flowability is widely recognized, the connection to the performance of printed parts has not been fully established. To address this, this study analyzes the influence of powder property differences on printed part performance using four batches of GH3536 powder produced with different atomization process parameters. The study found that the powder particle size distribution, sphericity, and satellite index directly regulate changes in flowability, but the microstructure (including grain size and texture) of the formed parts remains highly consistent under the same printing process. Parts produced with powders having high sphericity, low satellite particle content, and narrow particle size distribution exhibited the highest roomtemperature tensile strength. Subsequent hot isostatic pressing (HIP) and heat treatment (HT) significantly enhanced and homogenized the elongation performance of the printed samples, effectively reducing the influence of initial powder property differences. This finding holds significant engineering value for the industrial standardization of additive manufacturing.

Gears are essential components in mechanical systems, which are critical for motion transmission in industrial equipment. However, localized mixed-grain structures form in 20CrNiMo steel during warm forging at 800–900 °C, reducing gear service life. This study integrated finite element simulations and isothermal compression experiments to explore the formation mechanism of mixed-grain structures in steel during warm forging and subsequent heat treatment. Results showed that mixed-grain structure formation was collectively governed by strain-rate-dominated deformation-induced thermal effects, dynamic recrystallization mechanisms, and stored energy heterogeneity. Discontinuous dynamic recrystallization ‌dominated‌ at low strain rates due to relatively weak deformation-induced thermal effects. The recrystallization volume fraction remained low, with stored strain energy distributed uniformly. During subsequent heat treatment, nucleation preferentially initiated in unrecrystallized regions, promoting uniform grain growth. In contrast, at high strain rates, thermomechanical coupling induced dominant continuous dynamic recrystallization. Significant local kernel average misorientation differences generated stored energy gradients, driving grain boundary migration during heat treatment. Without precipitate phases to suppress this, abnormal grains grew via boundary migration, leading to mixed-grain structures. These findings establish theoretical foundations for suppressing mixed-grain defects in 20CrNiMo steel during warm forging and subsequent heat treatment.

High-entropy alloys exhibit significant potential for applications in extreme environments, particularly under high temperature and high strain-rate coupled loading conditions relevant to aerospace components. However, research on their mechanical properties under such coupled extreme conditions remains limited. Compressive behavior of the Al0.2CoCrFeNi HEA over a wide range of temperatures and strain rates was studied, using an improved Hopkinson pressure bar system and an electronic universal testing machine. The results demonstrate significant temperature and strain rate dependence of the flow behavior within the selected temperature and strain rate ranges. Third-type strain aging phenomenon, characterized by an anomalous flow stress peak within a specific temperature range and accompanied by Portevin-Le Chatelier serrated plastic flow, was observed under quasistatic condition and disappeared under high strain-rate conditions. The solute atomic in situ pinning mechanism dominated by Al atoms is comprehensively elucidated to further understanding of third-type strain aging phenomena in HEAs. Microstructural evolution at different temperatures and strain rates was characterized. Multiple deformation mechanisms, including twinning, dislocation slip, and dynamic recrystallization, were systematically investigated to elucidate their evolution with temperatures and strain rates. Finally, a deformation mechanism map was proposed over a wide temperature and strain rate range. This work provides fundamental insights into optimizing the strength-ductility synergy of HEAs for extreme environment applications, and the proposed deformation mechanism map offers guidance for the composition design and microstructure optimization of HEAs.

Transmission components necessitate materials that integrate high strength with wear resistance. Although ductile iron exhibits self-lubricating properties via graphite release, its tensile strength remains inferior to that of steel. This study develops a high-strength, self-lubricating Fe-0.9C-2.0Si steel by inducing graphite nucleation through martensitic transformation and optimizing the heat treatment process. By combining pre-generated martensite-induced graphite precipitation with heat treatment in the metastable phase region, a wear-resistant steel exhibiting high tensile strength, superior ductility, and excellent self-lubricating properties has been developed. To optimize the strength-ductility balance, tempering was performed. The results indicate that completely graphitized sample (650 degrees C/3 h) exhibited a 62 % increase in strength after quenching at 850 degrees C and tempering (500 degrees C/1 h), and its friction coefficient was 7 % lower than that of incompletely graphitized samples (650 degrees C/2 h) under the same post-treatment. Furthermore, tempering at 500 degrees C for 1 h improved plasticity compared to tempering at 300 degrees C for 1 h, facilitating the gradual and sustained release of graphite under severe wear conditions. This work proposes a processing route enabling graphite-martensite coexistence in high carbon steel, leveraging martensite to induce graphite formation while preserving it during quenching. This strategy advances the development of high-strength, wear-resistant steels with intrinsic lubrication.

To investigate the effects of alloying elements on the diffusion behavior of Mn and Al in TiAl alloys, a series of diffusion couples were prepared using a high-throughput diffusion multiple approach. The couples, which included Ti42Al5Mn-M (where M denotes 0, 0.8W, 0.8Mo, 2Nb, and 2Zr, at. %), Ti42Al, and Ti54Al, were aged at 1000 degrees C for 1000 h. The phase composition of the annealed samples and the concentration profiles of Al and Mn across the diffusion zones were systematically characterized by electron probe microanalysis (EPMA). Based on these profiles, the diffusion distances of Al and Mn were measured, and their interdiffusion coefficients in TiAl alloys containing W, Mo, Nb, or Zr were calculated according to Fick's second law. The influence of these alloying elements on the diffusion behavior of Mn and Al was comprehensively analyzed and discussed.

AlZnMgCu/TiB2 composites are prepared via the in-situ generation of TiB2 ceramic particles and subjected to hot extrusion and heat-treatment. XRD, SEM, EDS and TEM are used to characterize the composition, lattice structure and distribution of the secondary phases. The corrosion behavior of the composites is studied by electrochemical impedance spectroscopy, potential polarization measurements and corrosion morphology analysis. The effects of MgZn2 and Al2Cu precipitated phases and TiB2 ceramic particles on the corrosion behavior are discussed. The results show that the TiB2 ceramic particles are distributed along the extrusion direction and grain boundaries. Nano-sized MgZn2 and Al2Cu precipitates are evenly distributed in the alpha-Al matrix and form large grain boundary precipitates, resulting in precipitation-free zones. The corrosion of the composites is mainly pitting and intergranular corrosion. The pitting corrosion occurs in the alpha-Al matrix around TiB2 ceramic particles and the 0 phase. Two-electrode coupling systems are formed in the presence of TiB2 ceramic particles, which explain the mechanism behind the reduced corrosion of the alpha-Al matrix.

The trade-off between strength and ductility remains a persistent obstacle in the development of advanced structural materials. In the present study, a novel dual-heterogeneous structure with a bimodal grain distribution in both ferrite and austenite phases was fabricated via cold rolling and partial recrystallization annealing on solution-treated 2205 duplex stainless steel (DSS). The processed steel exhibited superior mechanical properties, with the yield strength increasing from 586 MPa to 903 MPa, and the ultimate tensile strength from 796 MPa to 1082 MPa, while maintaining a high total elongation of 35.3%. Based on in-situ electron backscatter diffraction (EBSD) and scanning electron microscope (SEM) analyses, the microstructural deformation behavior and strengthening mechanisms of the dual-heterostructured 2205 DSS were elucidated. The outstanding combination of strength and ductility was ascribed to the synergistic effects of grain refinement, dislocation strengthening, and hetero-deformation induced (HDI) strengthening. Moreover, the high ductility in DSS was attributed to the co-activation of cross-slip systems in ferrite {110} and {112} along with the single-slip systems in austenite {111}. These findings provide a new strategy for the design and development of high-strength and ultra-high-strength DSSs.

Electropulsing technique was first used for laser additive manufacturing (LAM) of Ni-based superalloy, and the effect of electropulsing treatment (EPT) on the dissolution behavior of Laves phase and tensile properties was investigated. The results show that EPT reduces the thermodynamic potential barrier during the Laves phase dissolution process by altering the free energy of the system, enabling the dissolution of Laves phase at a relatively low temperature (1050 degrees C). Moreover, the Laves phase preferentially dissolves in the region of small curvature radius under the current detour effect. Based on the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model, the dissolution kinetics of Laves phase under EPT was analyzed. The quantitative relationship of Laves phase dissolution kinetics under EPT and conventional heat treatment (CHT) was established. Theoretical analysis and quantitative calculations reveal that the diffusion coefficient of the EPT at 1050 degrees C is 10 times higher than under CHT. The decrease in Laves phase volume fraction leads to a significant increase in elongation. The lower treatment temperatures and shorter times effectively suppressed abnormal grain growth, resulting in a significant increase in elongation of the EPT-3 sample to 39.5 %. The failure mechanisms and crack initiation of as-deposited, EPT-3 and CHT-6 samples were systematically analyzed. It can be found that the required microstructure of the alloy can be rapidly achieved at lower temperatures by applying EPT. Compared with CHT, the EPT technology provides a clean, efficient, and limitless potential new post-treatment method for LAM Nibased superalloys.

To address the challenge of increasing the thickness of the nitriding layer, an intermediate annealing-twice nitriding process was applied to pure iron, and the corrosion resistance of the nitriding samples was investigated. After the intermediate annealing-twice nitriding treatment, the thickness of the compound layer in the sample increased by 84 % compared to once nitriding, reaching 48.14 mu m, while the transition layer thickness increased by 57 % to 52.49 mu m. The intermediate annealing process at 600 degrees C for 1 h yielded a superior twice nitriding effect. And the intermediate annealing-twice nitriding process resulted in a significantly thicker nitriding layer compared to simple twice nitriding. The phase transformation and thickening mechanism of the nitriding layer during the process were revealed by EBSD, XRD, and TEM. Electrochemical tests showed that the nitriding samples exhibited repeated passivation behavior, and the sample with a thicker compound layer demonstrated better corrosion resistance.

During two stage cold rolling, texture and formability at various reduction distribution coefficients (n) were investigated for ferritic stainless steel for elucidating the evolution of recrystallization texture and leveraging the advantages of this process. The shear band-induced crystallite occurred during cold rolling, and a model of crystallite-assisted gamma-fiber texture development was presented during annealing. High cold rolling reduction promoted the crystallite formation and their transformation into more stable {111}< 112> components, and the {111}< 112> recrystallized nuclei growth, while low cold rolling reduction retarded the phenomenon that the surrounding matrix of deformed grain occurring preferential nucleation was consumed through priority developed. -fiber recrystallized grain, and promoted the {111}< 110> recrystallized nuclei growth during final annealing. Hence, after final annealing, as n decreased (first and second stage cold rolling reductions increased and decreased, respectively), the gamma-fiber textures weakened and the fluctuation of intensity along gamma-fiber reduced, and the intensity of {110}< 001> component displayed a gradual increase followed by reduce. Moreover, as n decreased, the distribution for oriented grain clusters after annealing exhibited gradual uniformity followed by unevenness on account of low degree of microstructure fragmentation and high recovery tendency at lower cold rolling reduction and high nucleation and growth tendency of grains with similar orientations at higher cold rolling reduction. As n decreased, therefore, the ridging resistance and anisotropy of r-value displayed a step-by-step rise followed by a step-by-step reduce, and the difference in r-value was small. The n of 0.405 contributed to realizing optimal matching of r-value and its anisotropy and ridging resistance.