The development of ultra-high-strength Al-Zn-Mg-Cu alloys is often constrained by the trade-off between strength and ductility and by low incipient melting temperatures. This study overcomes these limitations by using a modified AA7097 alloy and an AA7097-0.22 wt% micro-sized SiC composite alloyed with Sc and Zr. A multi-step homogenization strategy, designed using differential scanning calorimetry, safely raised the solidus temperature from 467.8°C to 478°C, thereby eliminating incipient melting during solution treatment. Following an 85% hot rolling reduction, a non-recrystallized “pancake” grain structure was thermally stabilized by nanoscale Al3(Sc,Zr) dispersoids, which effectively suppressed static recrystallization. Crucially, the introduction of a 1% pre-stretch accelerated the multi-step aging response through dislocation-assisted heterogeneous nucleation. Under optimized processing conditions, the micro-SiC reinforced composite achieved an outstanding Ultimate Tensile Strength (UTS) of 705 MPa with 9% elongation, outperforming the monolithic base alloy (680 MPa UTS, 6.5% elongation). These findings demonstrate that coupling micro-sized reinforcement pinning with strain-induced precipitation kinetics provides a robust pathway for synthesizing advanced, high-ductility aluminum matrix composites.

This study demonstrates that microalloying with Fe, Ni, and Er establishes a permanent microstructural framework that significantly mitigates high-temperature softening. To establish the optimal thermal processing route for the co-modified alloys, homogenization treatments were evaluated at 490 degrees C for holding times of 4, 6, and 8 h, while the subsequent artificial aging kinetics were closely monitored over varying durations at 180 degrees C. Implementing the optimized heat-treatment route, consisting of a homogenization stage at 490 degrees C for 6 h followed by artificial peak aging (T6) at 180 degrees C for 8 h, successfully promoted the formation of a thermally stable microstructural skeleton. Phase transformations and microstructural evolution were characterized using differential scanning calorimetry (DSC), optical microscopy (OM), and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX). The mechanical behavior was evaluated using Vickers hardness testing and RT- and elevated-temperature compression testing. Mechanical properties evaluations showed that, at RT, the Fe-/Ni-modified alloy attained the highest compressive yield strength of 353 MPa, reflecting a 15.7% enhancement over the reference alloy (305 MPa), attributed to precipitation hardening within the alpha-Al matrix. Conversely, the Fe-/Ni-Er-modified alloy exhibited remarkable ductility, with a fracture strain of 0.78. Most notably, at 250 degrees C, the Fe-/Ni-Er-modified alloy maintained an ultimate compressive strength of 320 MPa, achieving a high strength retention rate of approximately 60.4% compared to its RT performance. This elevated thermal stability is attributed to the formation of a highly interconnected, rigid intermetallic framework comprising thermally stable Al9FeNi (T-phase) and Er-rich phases, which acts as a permanent load-bearing framework that effectively prevents macro-scale thermal softening and structural degradation of the alpha-Al matrix at elevated temperatures.

This study employs 3D molecular dynamics simulations to investigate deformation-induced martensitic transformation (DIMT) in both chemically homogeneous and heterogeneous austenite grains, with particular emphasis on the distinctive role of chemical boundaries. Our findings reveal three fundamental differences between chemical boundaries and conventional interfaces: (i) they do not serve as nucleation sites for martensite formation, (ii) they effectively arrest propagating martensite, yet (iii) they exhibit negligible influence on stacking fault transmission. In the Fe-Ni model system, we demonstrate that DIMT behavior in compositionally graded core-shell austenite grains is predominantly governed by local Ni concentration, where increased Ni content significantly enhances phase stability. These insights demonstrate that precisely engineered chemical heterogeneities offer an effective pathway for controlling DIMT behavior, providing a novel paradigm for designing next-generation steels containing retained austenite with tunable mechanical properties.

In-situ observations of critical damage evolution during uniaxial tensile of Al-Cu-Li alloys were performed by using micro-X-ray computed tomography (X-CT). The effects of microporosity nucleation and growth on microstructural damage failure were explored, and the fracture mechanism was eventually revealed. The digital volume correlation (DVC) technique is used to analyze the strain concentration effect during fracture. As for the multi-porosity (high porosity) microstructure, there is radial linking and merging of microporosities during tensile loading, and the predicted values of the McClintock model are in good agreement with the experimental values. Furthermore, the fracture failure of the alloy is highly correlated with the size and morphology of the microporosities. Microporosities with equivalent diameter D-eq>50 mu m and sphericity S < 0.25 are effective sites for crack initiation, which is the main microscopic mechanism causing fracture failure of the alloy. The linkage between microporosities during tensile loading is a preferential path but not a dominant factor in crack propagation. The DVC results indicate that during tensile-dominated loading, the value of the destructive strain at the largest microporosity (crack initiation strain) is 3-6 times higher than the experimentally observed value.

The synergistic effect of pre-deformation (0-10 %) on the aging precipitation behavior, microstructure evolution and strengthening mechanisms of 2195 Al-Li alloy. Results demonstrate that pre-deformation significantly enhances aging kinetics, reducing the peak-aging time from 30 h (0 % pre-deformation) to 18 h (10 % predeformation). The optimal pre-deformation level of 4 % yielded a superior combination of yield strength (525.01 MPa), ultimate tensile strength (550.57 MPa), and elongation (10.01 %). Compared to the non-deformed alloy, the pre-deformed (4 %) alloy exhibited a significant increase in dislocation density from 1.45 x 1014 m-2 to 5.12 x 1014 m-2. This enhanced dislocation density promoted the nucleation of considerably finer T1 precipitates, reducing their average diameter from 136.54 nm to 65.59 nm, while simultaneously suppressing the formation of the 0 ' phase. Pre-deformation effectively lowered the activation energy required for T1 precipitation from 159.78 kJ/mol to 153.40 kJ/mol, which led to an acceleration in nucleation kinetics. Quantitative strengthening mechanisms analysis indicated precipitation strengthening (234.8 MPa) as the dominant contributor in pre-deformed alloys. The study provides a ageing precipitation kinetics framework for optimizing pre-deformation parameters to achieve synergistic strength-ductility improvements in Al-Li alloys.

To improve the metallurgical quality of the melt prior to the holding furnaces and reduce the subsequent refining burden, it is essential to intensify early-stage melt purification. To overcome the limitations of conventional purification technologies, including complex equipment and high costs, an efficient purification method for aluminum alloy (6111) based on porous injection-flux synergy is proposed. Through systematic optimization of key process parameters, the intrinsic coupling mechanism for hydrogen degassing and inclusion removal is clarified. Porous injection generates fine bubbles that reduce hydrogen partial pressure and enlarging the gas-liquid interfacial area, thereby accelerating hydrogen mass transfer. Simultaneously, flux reactions form microbubbles and lower interfacial energy, promoting spontaneous inclusion adsorption, while bubble-induced turbulence enhances flux dispersion and inclusion collision probability. Under optimal conditions (400 L/h gas flow, 0.7 wt pct flux, 15 minutes treatment) for a 10 kg melt, hydrogen content decreased by 75.4 pct to 0.15 mL/100gAl, and the inclusion area fraction was reduced to 0.68 pct. Resultant as-cast properties improved to 70 HV hardness, 143.23 MPa tensile strength, and 10.1 pct elongation. Compared with conventional rotary degassing or single flux treatment, the proposed strategy enables simultaneous degassing and inclusion removal via thermodynamic–kinetic coupling, offering a basis for integrated melt purification design.

The interfacial heat transfer coefficient (IHTC), or contact thermal resistance, characterizes the heat transfer characteristics between two contacting objects. During the casting process, the cooling of the molten metal in the mold cavity relies mostly on the heat transfer between the metal and the mold. Therefore, the IHTC between the mold and the casting is crucial for the accurate prediction of temperature distribution in a casting component. In this study, a new methodology has been developed to obtain the full sets of IHTC in complex castings like wheel hubs. Using limited experimental data and finite element simulation results, such artificial algorithms as XGBoost, SVR, and Transformer have been applied to establish the correlation between output temperature distribution and input IHTC. It has been found that the XGBoost model performed best, which was then used as the objective function in a non-dominated sorting genetic algorithm (NSGA II) optimization. Therefore, accurate simulations have been performed by applying specific IHTC to different boundaries, enabling successful validation by experimental data from thermocouple measurements.

This study used X-ray microtomography to conduct in-situ observations of hydrogen micropore nucleation and growth during the directional solidification of an Al-Cu-Li alloy in a vacuum temperature gradient furnace. The kinetics of hydrogen microporosity evolution were traced and elucidated, and the micropore migration mechanism during directional solidification was revealed. The observed evolution of hydrogen microporosity can be divided into two basic stages: the first stage was characterized by micropore nucleation manifested as a sharp increase in the number density of micropores, with an average micropore nucleation temperature of (607 ± 9.6) °C and the maximum formation rate of 1.6 micropores/s; the second stage (560–595 °C) was dominated by micropore growth, as indicated by a significant increase in equivalent diameter at the maximum growth rate of 4.05 μm/s. The micropore growth kinetics were effectively described by an exponential function based on these observations. Notably, the Marangoni flow field induced by the differences in surface tension around the hydrogen micropores in the mushy zone caused them to migrate towards the cooler side of the temperature gradient, in contrast to the commonly observed migration of micropores towards the warmer side of directionally cooled metals; this atypical phenomenon was caused by the different effects of temperature and alloy component concentrations (Cu and Li elements) on surface tension. The cryophilic migration behavior observed in this study was primarily influenced by the Cu concentration, i.e., the Mukai-Lin-Laplace effect.

Traditionally, it is believed that more nanometer precipitates would produce higher mechanical properties in heat treatable Al alloys. In this study, it has been found that the reduction of coherent & ouml;' nano precipitates in Al-Li and formation of heterogeneous amorphous-crystalline interfaces upon two step aging actually break the strength-plasticity trade-off in high-Li content Al-Li alloys by using In-situ small-angle neutron scattering (SANS). By suppressing & ouml;' over-precipitation while inducing dynamic dissolution-reprecipitation cycles, excessive brittle & ouml;' (Al3Li) precipitates have been dissolved by an effective short-term two-step aging protocol (120 degrees C/4 h + 175 degrees C/20 min). SANS quantification of the temperature-dependent & ouml;' precipitation kinetics clearly demonstrates a dissolution-dominated regime at 175 degrees C that destabilizes classical coarsening models. Crucially, transient amorphization triggered by Li segregation forms heterogeneous amorphous-crystalline interfaces, which enhances plasticity and strain hardening by more effectively impeding dislocation shearing. These findings establish a new microstructure-tailoring strategy where controlled & ouml;' dissolution and meta-stable amorphization synergistically bypass strength-ductility compromises in Al-Li alloys.

Gas porosity defects and secondary dendrite arm spacing (SDAS) are the key microstructure influencing the mechanical properties of Al alloys and their predictions are critical for the safety and reliability of automotive casting components. Existing works mainly utilize experimental methods or numerical simulations to characterize the microstructure, which cost highly and offer limited physical insights. In this study, we generated a comprehensive porosity dataset (472 samples) via 3D cellular automata (CA) simulations and curated an SDAS dataset (310 samples) derived from published literature. Seven artificial intelligence (AI) algorithms have been systematically evaluated, and the eXtreme Gradient Boosting (XGBoost) was identified as the most robust model for microstructure prediction. To validate the AI models, X-ray computed tomography (X-CT) and metallographic experiments were conducted, and the results indicated an accuracy exceeding 90%. Beyond prediction accuracy, we employed SHapley Additive exPlanations (SHAP) analysis to elucidate the impact of alloy elements and processing parameters on the microstructure features, bridging the gap between "black-box" AI and physical insights behind. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

The influence of micropore characteristics on stress-limited crack propagations during tensile tests of Al-Si alloys is still qualitative rather than quantitative. In this study, in-situ X-ray computed tomography (XCT) has been employed to obtain the micropore damage evolution quantitatively in different regions of the uniaxial tension samples. By developing a novel micropore-tracking algorithm (MPTA), the characteristics of individual micropores can be quantified in nucleation, growth, and coalescence stages. The results reveal pronounced heterogeneity in micropore evolution. Prior to fracture, the ratio of maximum to minimum micropore growth rates in the spoke region is 15, while the average growth rate in the rim region (44.91) is substantially higher than that in the spoke region (13.01). Compared to classical micropore growth models, the Huang model shows better agreement with experimental observations (MRE = 0.83%, MaxRE = 3.74%) than the R-T model (MRE = 1.11%, MaxRE = 4.32%). The integration of digital volume correlation (DVC), three-dimensional fracture surface and SEM fractography further reveals region-dependent fracture mechanisms. In the spoke region, cracks initiate from edge micropores and propagate along micropore aggregation zones, accelerating fracture, whereas in the rim region, local strain induces oriented micropore coalescence bands that trigger fracture. Therefore, the findings highlight the influence of individual micropore heterogeneity and regional differences on fracture behavior, providing critical experimental evidence and guidance for improving micropore models and enhancing fracture prediction accuracy.

A coupled three-dimensional cellular automata (CA) model has been used to predict the hydrogen porosity in an Al-Si alloy as a function of thermal boundary conditions. By quantifying the porosity distribution from simulations, a porosity defect database was established, representing a cooling rate ranging from 0.25 to 50 degrees C/s at an initial hydrogen content of 3.0 & times;10-3 mL/g. Based on the database, four machine learning algorithms including support vector machine (SVM), random forest (RF), K-nearest neighbors (KNN), and gradient boosting machine (GBM) were trained and compared for each porosity characteristic to identify the optimal model. For the prediction of porosity percentage, the determination coefficient (R2) and the root mean square error (RMSE) on the test set reached 0.95 and 0.042, respectively. The predicted porosity distribution agreed well with experiments, indicating that the model can be used to map the porosity size in large casting components.

Selective Laser Melting (SLM) has great potential for fabricating high performance and complex parts but its application in Mg alloys is rather limited due to the trade-off between corrosion resistance and the strength-ductility properties. In this work, the properties of SLM-fabricated AZ91D alloy have been investigated as a function of heat treatment conditions and the evolution of microstructure has been quantified. It has been found that the size, distribution, and morphology of the β-Mg17Al12 phase are the core factors determining the comprehensive performance of the alloy. At T4 heat treatment, nearly complete dissolution of the β-phase has been achieved, while the formation of a coarse discontinuous β-phase network along grain boundaries has been observed after T5 heat treatment. Dispersed precipitation of fine needle-like β-phase within the matrix are observed after T6 heat treatment, resulting in optimal strength-ductility balance of the alloy. The strengthening mechanism was dominated by dislocation strengthening, and supplemented by Orowan strengthening, reaching an ultimate tensile strength of 308 MPa. Micro-galvanic corrosion between the β-phase and the a-Mg matrix has been observed, whereas the uniform distribution of precipitates improves corrosion resistance. Therefore, the mechanism of tailoring both strength-ductility together with corrosion resistance by controlling β phase size and distribution has been found for SLM-fabricated AZ91D alloy, providing further process optimization strategy for additively manufactured Mg alloys.

Prompted by the lightweighting strategy for new energy vehicles, integrated die-casting Mg alloy technology has emerged as a research hotspot due to its combined weight reduction potential and emission reduction benefits. This work focuses on three critical dimensions within the Mg alloy integrated die-casting technology system: material alloy design, forming defect mechanisms, and the influence of process on performance. It establishes a comprehensive material-process-performance analytical framework. This approach aims to overcome the fragmented nature of current theoretical research, providing foundational support for building a scientific theoretical framework for magnesium alloy integrated die-casting. Ultimately, it facilitates the continuous advancement of this technology towards higher precision and greater reliability

Microporosity is one of the most typical defects in Al-Li alloys fabricated by Wire Arc Additive Manufacturing (WAAM), and it leads to cracks under tensile loading. However, no studies have been focusing on the complex coupling phenomenon of microporosity evolution and internal stress/strain re-distribution under tensile loading and thus critical damage mechanism (delamination or transgranular propagation) in such new materials as WAAM Al-Li alloys is still un-known. To clarify this, X-ray Computed Tomography (XCT) is used to track the entire crack initiation and propagation process as a result of microporosity characteristics, including its growth, aggregation, and strain re-distribution in WAAM Al-Li alloys under tensile loading. It has been found that with increasing strain, the aggregation of large-sized micropores as a result of strain concentrations has been observed. Cracks initiate from the large-sized micropores and expand rapidly along the clusters of microporosity instead of non-weldable chain of the inter-layer region and the elongated micropores or longitudinal clusters of microporosity are responsible for the intergranular propagation of cracks instead of the transgranular small-sized porosity path. The analysis of stress redistribution and nearest neighboring of large-sized micropores during the tensile test identifies the correlation between the fracture path of WAAM components and large-sized porosity aggregation zone. Therefore, critical damage characteristics of WAAM Al-Li alloys have been found and their mechanical properties can be improved by minimizing the clustering of microporosity with a size greater than 50 lm. (c) 2025 The Author(s). Published by Elsevier Ltd on behalf of Chinese Society of Aeronautics and Astronautics. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Automotive wheels are critical components for vehicles' safety and durability because their fatigue failure under cyclic loads is unusually catastrophic. Fatigue cracks typically initiate from such defects as gas and shrinkage pores formed during solidification in low-pressure die casting process of wheels. However, it is still largely unknown which micropore characteristic determines the degradation of mechanical properties in aluminum automotive wheels. In this study, X-ray computed tomography (XCT), finite element analysis (FEA), and digital image correlation (DIC) were employed to investigate the effects of micropore size, morphology and distribution on the mechanical properties at different wheel locations. It has been discovered that, using multiple machine learning methods, the ratio of the projected area of micropores to their shortest distance from the free surface (PA/SD) exhibits the strongest correlation with the stress concentration factor (Kt) around the micropores, achieving a correlation coefficient of 0.90 and demonstrating a linear relationship. DIC and three-dimensional fracture analysis confirmed that regions with high PA/SD values are the primary cause of strain concentration, leading to crack initiation. Therefore, methods of effectively eliminating large micropores near the edges can significantly enhance the mechanical properties of automotive wheels.

In material design, preventing crack propagation is crucial for improving structural reliability and extending service life. Here, we report a new phenomenon where the soft n-Li phase in Mg alloys coexists with the hard a-Mg phase, and very hard Al2RE precipitates form at the interface between the n-Li and a-Mg phases, exhibiting a multiphase heterogeneous microstructure. By using X-ray tomography, we have observed the arresting of cracks at the n-Li/a-Mg interface and cracking is only allowed along the very hard Al2RE precipitates, increasing the strength and ductility of the three-phase alloy significantly. From atomistic molecular dynamic simulation, three-phase alloys enhance strain hardening through {112} dislocation slip mechanisms, which create barriers to crack propagation. In-situ observation and crystal plasticity finite element coupled with phase field (CPFE-PF) have shown that most cracks are arrested by the interconnected n-Li phase network, and cracks have to propagate along the tortuous paths, limiting their mobility. Therefore, this finding lays the foundation for high ductility and durability design of Mg alloy by arresting the initial cracks in their diversifying soft/hard neighboring cells.

The new generation of cast Al-Cu-Li alloys offers a benefit in both high strength and stiffness, while the ductility of these alloys is generally poor, restricting their application in aerospace industries. In this work, the cast Al-CuLi alloy micro-alloyed by Ti, Zr, and Sc was prepared by argon-shielded metal mold casting. The as-cast alloy possesses the complete equiaxed grains which exhibit good resistance to coarsening during solution annealing treatment. The microstructure including secondary phase, grain size, and precipitates were characterized by SEM, EBSD, and TEM, respectively. We find that the using of rare earth element Sc combined with its dragged effect on precipitation kinetics at 120 degrees C can optimize the strength-ductility balance of the cast Al-Cu-Li alloy. The alloy yields evident heterogeneous nucleation of " delta '+theta' " precipitates with delta ' phase wetting outside theta ' layer around Sc-clusters when aged at 120 degrees C for 100 h. Those fine precipitates result in an improved work-hardening capability compared to the coarse " T1+delta '+S' " precipitates forming at 160 degrees C aging process. Applying those principles to the new cast Al-Cu-Li alloy, a combination of mechanical properties with tensile strength at 482 MPa and elongation at 6.0 % has been achieved.

In this study, a finite element-based fatigue prediction method that incorporates mesh size, casting defects, and secondary dendrite arm spacing (SDAS) is proposed. First, the grid convergence index (GCI) theory is employed to assess the mesh independence of fatigue life simulations for wheel radial fatigue, leading to the determination of an optimal mesh size of 5 mm. The aluminum alloy wheel casting process, including the assessment of casting defects and cooling rate distribution, is then simulated using a finite element model. An algorithm for transferring data from the process simulation model to the structural simulation model is developed. As a result, a radial fatigue model that accounts for the effects of porosity and SDAS in the wheel is established. The integrated fatigue model is used to predict the influence of mesh size, casting defects, and SDAS on wheel fatigue performance, enabling accurate prediction of radial fatigue life as a function of casting conditions. This work lays the foundation for process optimization aimed at improving the service life of aluminum wheel castings.

Ring artifacts are common artifacts in X-ray Computed Tomography (XCT) scans and have a significant impact on subsequent feature/phase extractions due to the small grayscale gradients in XCT volume data of bulk materials. This paper proposes the Haar Dual Domain Network for correcting ring artifacts. By utilizing the Haar wavelet decomposition on images containing ring artifacts in both the image and projection domains, the ring artifacts are preliminarily separated, facilitating their removal by neural networks while preserving microstructure features such as low-contrast phase boundaries. By constructing a feature fusion network, the information from both 2D slices and 3D projection volume data has been fully integrated to eliminate ring artifacts while preserving the edges of every feature. The effectiveness of the Haar wavelet transform and fusion network has been validated by ablation experiments, proving the application of HDD-Net to large volume of XCT data.