A novel Al-5Ti-0.25C-4Sr master alloy was synthesized sustainably from Al/Ti machining chips to overcome Si poisoning in A356 alloys. The master alloy exhibited synergistic alpha-Al grain refinement and eutectic Si modification in A356 alloy. The optimal addition (1.2 wt%) effectively reduced the average alpha-Al grain size and eutectic Si were reduced by 46.5% and 69.3%, leading to a 53.1% enhancement in ultimate tensile strength (150 MPa) compared to the unmodified alloy. Microstructural analysis revealed that the refinement stems from heterogeneous nucleation on TiAl3, TiC, and Ti2Al20Sr particles. The modification was attributed to Sr-induced twinning, which was further elucidated by first-principles calculations showing strong Sr adsorption on the Si (100) surface. This work provides a cost-effective and eco-friendly strategy for high-performance Al-Si alloy production.

Magnesium rare earth (Mg-RE) alloys generally exhibit insufficient strength and ductility because of their coarse grains, which restricts their engineering applications. Grain refinement can be effectively achieved by adding Al. This study investigates the effect of Al addition on grain refinement and the mechanical properties of a Mg-6Gd-3Y alloy. Mg-6Gd-3Y alloys containing different Al contents (0, 0.5, 1.0, 1.5, 2.0, and 3.0 wt.

The electronic and thermal transport properties of Al2Cu and Al-Fe-Si intermetallic compounds were investigated through first-principles calculations based on density functional theory. The electronic structures, including the energy bands and density of states (DOS), were analyzed, which revealed metallic characteristics for Al2Cu, Al2Fe3Si4, Al8Fe2Si and Al5FeSi, while Al2Fe3Si3 exhibits semiconducting behavior. Phonon spectra and phonon DOS were calculated to evaluate lattice dynamics, confirming the dynamic stability of all compounds and identifying the dominant vibrational contributions of Fe and Si atoms. The electrical conductivities were calculated using Boltztrap2 code, and the electronic thermal conductivities were derived from the Wiedemann-Franz law. Lattice thermal conductivities were determined by the ShengBTE code, with Al2Fe3Si3 exhibiting the highest lattice thermal conductivity among the investigated compounds. The comprehensive analysis provides valuable insights for optimizing the composition of aluminum alloys for enhanced thermal properties, thus supporting the development of advanced aluminum-based materials for various industrial applications.

L12-TiAl3 is a common phase in aluminum alloys, known for its reliable (010) bonding with Al, yet the intrinsic origin of this interfacial strength remains elusive. Here, first-principles calculations are employed to investigate the L12-TiAl3/Al (010) interface, aiming to elucidate the essential mechanism of interfacial strengthening. The results reveal that (Al + Ti)-terminated slabs yield positive interface energies of 4.83-4.34 J/m2 (top), 4.25-3.76 J/m2 (bridge), and 3.52-3.03 J/m2 (hollow), while Al-terminated slabs give negative values of-6.76 to-6.27 J/ m2 (top),-6.57 to-6.07 J/m2 (bridge), and-6.29 to-5.79 J/m2 (hollow). Notably, the top site configuration of the Al-terminated slab yields the most negative interface energy, indicating spontaneous interfacial bonding. This negative interface energy is identified as the fundamental origin of the high interfacial strength of the L12-TiAl3/Al (010) heterogeneous interface, a conclusion further corroborated by calculations of the work of adhesion. Subsequent electronic structure analysis reveals that (Al + Ti)-terminated interfaces exhibit stronger antibonding characteristics compared to the Al-terminated counterparts, accounting for their relatively lower interface strength. Moreover, significant electronic rearrangement is observed at the Al-terminated interfaces, enhancing the covalent bond character while reducing the metallic bond contribution. This chemical bonding transition imparts the interface with superior bulk-like mechanical strength.

Commercially applied 1060 current collector battery aluminum foil was selected as the base material for the addition of rare-earth element Ce. Melting, degassing, filtration, hot rolling, and cold rolling processes were conducted on the Ce-added aluminum foil. The influence of Ce addition on the 1060 current collector battery aluminum foil was analyzed. Results indicate that AlCeSi intermetallic phases are generated in the 1060 current collector battery aluminum foil and act as heterogeneous nucleation sites, therefore refining the grains. In the cold rolling deformation process, the Ce-containing secondary phase particles at the grain boundary produces a strong Zener pinning effect, increases the dislocation density, and inhibits the recrystallization. Consequently, the mechanical properties of the aluminum foil are enhanced through the synergistic actions of grain refinement strengthening and dislocation strengthening. Ce addition also reduces the impurity element solubility in the matrix, modifies lattice distortion scattering, and therefore enhances electrical conductivity. Adding the rare-earth element Ce can refine grains and promotes the positive shift of corrosion potential, thereby improving the corrosion resistance.

Tailoring the morphology and distribution of intermetallic compounds dictates the mechanical performance of magnesium alloys. However, the synergistic and competitive roles of multi-rare-earth additions remain elusive. Here, we investigate the co-addition of Y and La in the AZ91 alloy, revealing a synergistic toughening mechanism that shifts the fracture mode from brittle cleavage to ductile failure. Specifically, La addition refines the coarse Al2Y phase, thereby delaying micro-void initiation. Concurrently, Y triggers a distinct morphological transition in the Al11La3 phase, converting it from an intrinsic high-aspect-ratio needle to a coarsened rod structure. By coupling transmission electron microscopy with first-principles calculations, we trace the atomic-scale origin of this transition to dual-site occupancy mechanism. During the growth of the Al11La3 phase, Y occupation at Al sites on the lateral (0 1 0) facets induces severe localized lattice expansion, which destabilizes the facet and creates more Al atom adsorption sites, thereby leading to irregular lateral coarsening. Conversely, along the [0 0 1] growth axis, Y possesses a stronger adsorption energy and a concentration advantage, allowing it to preferentially occupy La sites during the growth process. This triggers lattice contraction of Al11RE3 and a strong solute drag effect, kinetically suppressing longitudinal elongation. Ultimately, this work provides fundamental insights into the strength-toughness synergy in Mg-Al-RE systems and highlights a promising pathway for tailoring intermetallic anisotropy via atomic-scale solute-lattice coupling.

To overcome the restriction that the solid-state recycled processes can only be performed for the single brand of aluminium alloy chips, the feasibility of solid-state recycling of ADC12 and 6005A aluminium chips at varying ratios was investigated. The chips were first mixed by ball milling and then hot compacted before hot extrusion. The results revealed that ball milling can effectively mix and refine the chips, the chips gradually refined as the milling speed increased, in contrast, the milling time and the ratio of mixed chips had little effect on the morphology and average size of the chips. Microscopic examination showed that the recycled alloy with a mixing ratio of 9:1 between ADC12 and 6005A alloy achieved the best bonding quality, with the oxide layer and Fe-rich phases crushed and dispersed in the Al matrix, which improved the strength of the recycled alloy through the dispersion strengthening mechanism. The tensile test results also showed that the recycled alloy with the ratio of 9: 1 between ADC12 and 6005A alloy has prominent mechanical properties, with the ultimate tensile strength, yield strength, and elongation of 271 and 151 MPa, and 12 % respectively. The investigation in this work provides a novel and effective method for the recycling of aluminium alloy chips and contributes to the sustainable resource utilization of the aluminium industry.

A novel mechanical stirring method integrating homogeneous A356 internally cooled blocks is developed for A356 semi-solid slurry fabrication. A thermal-flow-phase change multiphysics model is established to investigate the effects of stirring rate and cooling block to melt mass ratio on the evolution of multiphysics fields. The optimal parameters (10% cooling block to melt mass ratio, 2000 r/min) yield the most uniform temperature and solid phase fraction distribution, which is confirmed by both metallographic characterisation and quantitative temperature validation.

To gain a deeper understanding of how diverse microstructures influence the thermal conductivity of Al-Si alloys, the mechanism governing thermal conductivity variations in ADC12 alloy was elucidated through directional solidification and subsequent heat treatment processes. The contributions of grain boundaries, second phases, and solid-solution atoms to thermal conductivity were qualitatively evaluated. Results show that directional solidification substantially eliminates transverse grain boundaries, and the thermal conductivity reaches 189.59 W·m−1·K−1. After 24 h solid solution treatment, the average grain size decreases from 57.10 µm (as-cast) to 21.65 µm and the aspect ratio of eutectic Si reduces from 8.94 to 4.52. However, the extensive solid solution of Cu in the α-Al matrix induces severe lattice distortion, significantly reducing the thermal conductivity to 135.40 W·m−1·K−1. The achievement of high thermal conductivity is attributed to the substantial elimination of grain boundaries, which serves as a critical mechanism for thermal conductivity enhancement of ADC12 alloy. These findings provide novel strategies and theoretical insights for achieving excellent thermal conductivity in aluminum alloys by customizing their microstructures.

In this study, plasma arc additive manufacturing (PAAM) was employed to fabricate Inconel 718 deposition specimens, and their microstructure and corrosion properties were investigated in the as-deposited and various heat-treated states. The as-printed (ASP) condition exhibited a typical dendritic structure with pronounced intergranular Laves phase segregation, strong < 100 > texture, and coarse grains. After high-temperature homogenization, the Laves phase was effectively eliminated in the homogenized (HOM) specimens, accompanied by significant recrystallization. The < 100 > texture intensity decreased from 34.81 to 19.32, the average grain size was refined from 207.2 to 103.18 μm, and the microhardness decreased from 267.6 to 211.5 HV0.2. In contrast, the homogenization + solution-aging (HSA) specimens exhibited needle-like δ phase precipitation along grain boundaries, with < 100 > texture intensity increasing to 30.71 and grain size coarsening to 183.67 μm. The precipitation of γ″/γ′ strengthening phases led to a substantial increase in microhardness to 447.9 HV0.2. Electrochemical tests in 3.5 wt.

The electromagnetic stirring method has become one of the important methods for producing semi-solid slurries. Researchers typically use numerical models based on constant thermophysical parameters to predict the desired metrics. However, due to the fact that thermophysical parameters vary with temperature, this model leads to deviations in simulation results. Consequently, in this study, a three-dimensional model based on dynamic thermophysical parameters was constructed to simulate the electromagnetic field-velocity field-temperature field during the electromagnetic stirring of semi-solid aluminum alloy melt. Furthermore, the results were compared with those a constant-parameter model. The simulation model was verified through experiments such as magnetic induction strength measurement, temperature measurement, and metallurgical morphology analysis. The results reveal that the fluctuation trend of velocity at monitoring points obtained from the dynamic thermophysical parameters model exhibits better consistency with the actual situation during three-phase alternating-current electromagnetic stirring. Meanwhile, the temperature distribution trend predicted by the dynamic parameter model aligns more closely with the measured data. In addition, at the monitoring points, the simulated curve based on the dynamic thermophysical parameter model demonstrates superior agreement with the experimental measured values.

Low-cost (TiAl3+TiC)/Al composites have emerged as promising materials for applications requiring both wear resistance and lightweight properties, such as printer guides and granular material conveying pipelines. This study successfully synthesized in-situ (TiAl3+TiC)/Al composites via an integrated processing approach combining conventional casting with subsequent hot extrusion. Microstructural analysis demonstrates that the synergistic grain refinement effect of TiAl3 and TiC reduces the average grain size of the as-cast composite to 136.5 mu m. Mechanical testing reveals that the as-cast (TiAl3+TiC)/Al composite already surpasses extruded pure Al in strength. Hot extrusion induced dramatic grain refinement (4.3 mu m) through dynamic recrystallization and Zener pinning effect of TiC, while simultaneously transforming casting pores into uniformly dispersed microvoids and fragmenting plate-like TiAl3 into granular morphologies. Remarkably, the extruded composite exhibited a 42.23 % enhancement in ultimate tensile strength (retaining 23 % elongation) compared to the as-cast state. The simultaneous strengthening-toughening originates from four coupled mechanisms via grain refinement, thermal expansion mismatch, load transfer, and Orowan strengthening. Fracture analysis confirmed superior damage tolerance in the extruded composites, where TiAl3 fragmentation mitigated crack propagation and deformation enabled uniform void coalescence. These findings provide a generic pathway for designing high-performance aluminum matrix composites through controlled in-situ phase morphology and defect management.

In this study, an Al-15%Mg2Si-5%TiB2 composite was prepared using A356-5wt.%TiB2 alloy and pure Mg. The composite was then subjected to semi-solid isothermal heat treatment via a strain-induced melt activation (SIMA) process. The influence of holding temperature on the microstructure, mechanical properties, and tribological behavior of the composite was systematically investigated, and the results indicate that the optimal semi-solid microstructure was achieved when the composite was held at 625 degrees C for 1 hour. Compared to the sample treated at 610 degrees C, the composite exhibited significant improvements in hardness (20.02%), yield strength (2.87%), ultimate tensile strength (9.79%), elongation (66.99%), and wear resistance (26.25%).

Amorphous carbon (APC)/A6061 laminated composites were synthesized via the hydrothermal carbon adsorption on plates (HTCAP) followed by vacuum hot-press sintering (VHPS). The effects of hydrothermal temperature on the microstructural evolution, mechanical properties, and tribological properties of the composites were systematically investigated. The results reveal that the amorphous carbon, which was formed from glucose, was coated on the surface of the A6061 plate by electrostatic adsorption and then uniformly dispersed within the layers of the APC/A6061 laminated composites. With the progressive elevation of the hydrothermal temperature, the morphology of APC underwent a remarkable transformation from a flocculent state to an agglomerated and cross-linked spherical state. The flocculent APC was well bonded with the Al layer through the diffusion of Al. When the hydrothermal temperature was 150 degrees C, the APC/A6061 laminated composites exhibited the optimal tensile properties (ultimate tensile strength of 155 MPa and yield strength of 118.4 MPa) and tribological properties (average COF of 0.33 and wear rate of 0.69 x 10-5 mm3/Nm). The improvement in the tensile properties of the laminated composites can be primarily ascribed to the enhanced interfacial bonding and the grain refinement of matrix alloy. The predominant wear mechanism of the APC/A6061 laminated composites was adhesive wear. The formation of a homogeneous APC lubricating film on the wear surface and the increased hardness contributed to the enhancement of wear resistance.

The six well-known TiAl3 morphologies, from Type A to F, have been extensively documented. This study reveals three newly identified morphologies in Al-Ti-C alloys-nearly equidimensional blocky, symbiotic blocky-platy, and platy structures-through microstructural analysis under varying solidification conditions. Additionally, first-principles calculations are employed to explore the mechanisms behind their morphological formation. Under natural cooling, TiAl3 with the tetragonal structure forms a four-fold symmetric dendritic morphology with pronounced secondary branching. Cooling in a 500 degrees C preheated mold for 10 min results in a symbiotic blocky-platy morphology, except for discrete blocky and platy morphology, while extending mold cooling to 30 min leads to purely blocky and platy forms, completely devoid of dendritic features. Across all morphologies, lattice thermal conductivity remains independent of preferred growth. Additionally, the (001) surface consistently serves as the dominant exposed facet because of the lowest surface energy. Notably, the newly discovered blocky morphology is nearly equidimensional, distinct from previously reported plate-like blocks with perfect facets. While dendritic and platy morphologies may appear similar (needle-like) in 2D, they differ significantly in 3D, with platy forms typically lacking dendritic substructures. Platy morphology arises from dendritic arm coarsening and fusion. Furthermore, twinning not only drives the formation of interpenetrating crystals but also participates in blocky morphology development. TiAl3 with the cubic structure has the highest thermal conductivity along [111], but its (110) plane has the lowest surface energy and highest interface roughness. Similar contradictions exist in the orthorhombic structure.

In the present investigation two smart prediction tools, namely the multiple regression analysis and general regression neural network models were developed to predict average grain size and shape factor of the semi‐solid AZ91D magnesium alloy microstructure prepared by mechanical stirring. The process parameters (stirring temperature, stirring rate, stirring time) were considered as input variables to establish predictive models. The models were developed using the multiple regression analysis was employed to determine the significance of process parameters on microstructure. In the general regression neural network models, the k‐fold cross validation method is used to optimize the smoothing factor. The neural network models were trained, validated and tested. The results show the general regression neural network models achieve higher prediction accuracy for predicted error within 5 % compared with regression models within 10 %, which suggests that the model is more reliable. Finally, the accuracy of models was demonstrated based on experimental verification, asserting that they can provide a foundation for developing a comprehensive prediction system to optimize the structural and processing of semi‐solid magnesium alloys.

Different microarc oxidation (MAO) composite coatings were prepared on 6063 aluminum alloy by incorporating TiO2 particles and/or polytetrafluoroethylene (PTFE) emulsions. The microstructure, wear properties and corrosion behavior of the obtained coatings were comparatively investigated via multiple methods in this work. The results showed that the TiO2 and PTFE particles sealed the micropores and cracks due to the electrophoretic effect, which decreased the coefficient of friction (CoF) and improved the corrosion resistance compared with those of the pure MAO coating. Moreover, for the MAO/TiO2/PTFE coating formed by simultaneously introducing TiO2 and PTFE into the base electrolyte, a TiO2/PTFE outer layer was produced by cross-linking and chemical bonding reactions during the MAO process. The PTFE particles in the electrolyte were activated and self-charged by the synergy of the thermal field and the microarc discharge effect, which promoted the formation of the TiO2/PTFE outer layer. The CoF of the MAO/TiO2/PTFE coating significantly decreased to 0.28, and the corrosion current density was approximately three orders of magnitude lower than that of the pure MAO coating, indicating excellent wear and corrosion resistance.

Lightweight aluminum alloy conductor materials（Al-Mg-Si alloys） require not only high electrical conductivity to reduce electrical loss, but also high strength to withstand extreme weather conditions. To improve electrical conductivity and mechanical properties of Al-Mg-Si alloy simultaneously, the rare earth La was introduced to modify the Al-Mg-Si alloy. The effect of La addition on the microstructure, tensile properties and electrical conductivity of cast Al-Mg-Si alloy was investigated systematically. Results indicate that the appropriate La content is helpful to improve the strength and electrical conductivity of Al-Mg-Si alloys. When the addition of La is 0.2wt.%, the α-Al grains are refined apparently, Mg and Si solute atoms in the Al matrix are reduced by the formation of Mg 2 Si phase; the distribution of Al 11 La 3 phases is uniform, and the morphology of AlFeSi phase transforms from continuous state to discontinuous state. The Al-Mg-Si-0.2La alloy exhibits the optimal tensile properties and electrical conductivity, with an ultimate tensile strength of 170 MPa, a yield strength of 88 MPa, an elongation of 18.9%, and an electrical conductivity of 44.0% IACS. These values represent improvements of 9.0%, 15.8%, 70.3%, and 17.3%, respectively, compared to the Al-Mg-Si alloy without La addition. However, excessive La deteriorates the properties of Al-Mg-Si-xLa alloys.

Download This Paper Open PDF in Browser Add Paper to My Library Share: Permalink Using these links will ensure access to this page indefinitely Copy URL Copy DOI