Engineering heterogeneous structures has proven an effective strategy to overcome the strength-ductility trade-off. Controlling recrystallization during thermomechanical treatment represents a promising approach for large-scale fabrication of heterogeneous materials. Herein, we report the control of recrystallization and the fabrication of heterogeneous Al-Zn-Mg-Cu-Sc-Zr alloys via strain-induced boundary migration. We demonstrate that in-situ formed primary and secondary Al-3(Sc, Zr) particles induce partial recrystallization and pin dislocations, respectively. These effects collectively facilitate the growth of recrystallized grains during subsequent cold rolling via dynamic strain-induced boundary migration. The established model reveals that dynamic strain-induced boundary migration is suppressed when the ratio of the volume fraction to the size of dispersed particles exceeds 1.1 x 10(6) m(-1). After aging, the recrystallized grains grow further, ultimately forming a heterogeneous structure. Both the heterogeneity and mechanical properties can be tailored by adjusting the cold rolling reduction. Specifically, the aged alloy subjected to 2 % cold rolling strain exhibits similar to 35 % fine grains with the remainder being coarse grains, achieving a yield strength of 700 MPa and an elongation of 9.7 %. This enhanced strength-ductility synergy is attributed to two key factors: (1) the generation of geometrically necessary dislocations in coarse grains during deformation, and (2) the shearable Guinier-Preston II zones induced by secondary Al-3(Sc, Zr) particles. Our work provides a viable route for designing heterogeneous materials by mediating the growth of recrystallized grains.

Coexisting of TiB2 and primary Al3(Sc, Zr) shows high potential to enhance grain refinement. This study investigates the grain refinement and heterogeneous nucleation mechanism of Al-Zn-Mg-Cu-Zr-Sc alloys in the presence of coexisting TiB2 and primary Al3(Sc, Zr). An anomalous evolution of as-cast grain size was observed. The grain size initially decreases to 7.1 mu m after adding 0.1 wt% TiB2, but coarsens to 12.0 mu m at TiB2 addition of 0.5 wt%. Both experimental results and density functional theory calculations reveal TiB2 can act as nucleation substrates for primary Al3(Sc, Zr), which subsequently nucleate Al grains. This two-step nucleation contributes to the formation of fine grains. In contrast, high TiB2 additions can induce Sc/Zr poisoning effects. This study provides a practical approach to achieving refined as-cast grains in Al alloys by leveraging the synergistic effects of mixed grain refiners.

Heterogeneous microstructures present an effective strategy to improve the strength-ductility synergy in metallic materials. However, most studies focus on the effect of heterogeneous grains, while the regulatory methods of heterogeneous precipitates and their influence on the strength-ductility synergy remain less explored. This work reports a method for tailoring heterogeneous precipitates in age-hardenable Al-Zn-Mg-Cu alloys by controlling dynamic precipitation during cold rolling. Our results show that increasing the cold-rolling strain from 20% to 60% induces a transition from uniform to non-uniform dynamic precipitate distributions, with preferential growth first occurring near dislocations and later along low-angle grain boundaries. Quantitative models are established to describe the growth and distribution of dynamic precipitates as a function of cold-rolling strain. After subsequent aging, Al-Zn-Mg-Cu alloys with 40% cold-rolling strain exhibit bimodal precipitates and achieve the highest yield strength (638 MPa) and elongation (9.1%). Based on theoretical analysis and atomistic simulations, we propose a bimodal mechanism to account for the excellent strength-ductility synergy and guide the tailoring of heterogeneous precipitates in age-hardenable Al alloys: precipitates with a size of 32-41 nm act as sustainable dislocation sources to enhance ductility, while fine precipitates serve as effective dislocation barriers to maintain high strength. This work establishes a novel approach to optimizing the strength-ductility balance in Al-Zn-Mg-Cu alloys by engineering heterogeneous precipitates, providing insights for the design of advanced precipitation-strengthened materials.

The rapid rise of antibiotic-resistant bacteria has become a critical concern for human and animal health, highlighting the pressing need for alternative antibacterial approaches. Nonetheless, the poor antimicrobial performance and single-use nature of conventional antibacterial materials severely restrict their commercialization and large-scale utilization. In this study, we successfully developed a silver nanoparticle-anchored oxygen vacancy-rich alumina (Ag NPs/Ov-Al2O3) antimicrobial agent, which synergistically enhances silver atom utilization efficiency while maximizing active site density compared to conventional gamma-Al2O3 and Ag NP-based systems. Experimental and theoretical analyses demonstrated that Ag incorporation induces a substantial increase in oxygen vacancy (Ov) concentration within Al2O3 and optimizes its electronic configuration, thereby facilitating efficient oxygen molecule adsorption and activation. Remarkably, this structural modulation enables sustained reactive oxygen species (ROS) generation even under dark conditions-a breakthrough addressing the limitations of light-dependent antimicrobial agents. Density functional theory (DFT) calculations further elucidated that Ag NPs, coupled with enriched Ov sites, synergistically amplify interfacial interactions with bacterial membranes, leading to membrane disruption and intracellular damage. This antibacterial strategy based on Ag NPs/Ov-Al2O3 offers a highly efficient and environmentally friendly solution for indoor air filtration and sterilization, effectively overcoming the limitations associated with low-light environments.

The main component of high-capacity silicon-based electrodes is silicon powder, which necessitates intricate processing to minimize volume growth and powder separation while guaranteeing the ideal Si content. This work uses the an situ high-pressure forming approach to create an MXene/m-Si/MXene composite electrode, where MXene refers to Ti3C2TX, and m-Si denotes two-phase mixed nano-Si particles. The sandwich shape promotes silicon’s volume growth and stops active particles from spreading. The conductive structure of Ti3C2TX MXene increases the efficiency of charge transfer while reducing internal resistance. After 100 cycles, the composite electrode’s original capacity of 1310.9 mAh g−1 at a current density of 0.5 A g−1 is maintained at 781.0 mAh g−1. These findings lay the foundation for further investigations into Si matrix composite electrodes.

Materials with a final heterogeneous structure (HS) possess an excellent combination of strength and ductility. However, fine and homogeneous grains are desired in as-cast ingots to avoid defects. The evolution from an as-cast homogeneous microstructure to a pronounced HS owing to the trace addition of TiB2 particles was studied in Al-Zn-Mg-Cu alloys with traditional thermomechanical treatment. It is revealed that the triple junctions and over 2 μm precipitates co-located with TiB2 enhance the particle-stimulated nucleation of recrystallization. The dislocation density difference between the recrystallized and recovered grains is further enhanced by cold rolling. A pronounced HS with alternating soft and hard domains accompanied by multimodal precipitates is modulated, realizing a synergy of yield strength as 632.4 MPa and elongation as 8.8%. It is confirmed that the HS, rather than precipitates, is the primary source of geometrically necessary dislocations (GNDs), leading to the synergy of strength and ductility. Atomistic simulations on the deformation behavior of HS were used to elucidate the strain partition and role of GNDs on mechanical properties. Our results provide a convenient route to fabricate heterogeneous Al-Zn-Mg-Cu alloy by trace addition of ceramic particles in ingots casting instead of elaborated controlling of deformation processing.

Achieving uniform grain size in ingots is challenging in traditional direct chill (DC) casting. The thermal conditions during solidification often result in smaller grain size at the edge of the ingot compared to the center, leading to grain size inhomogeneity even in centimeter-scale samples. In this study, a low-flow pouring technique with the addition of grain refiner is employed to create similar thermal conditions from the edge to the center of the ingot during solidification, resulting in a homogeneous ingot. The grain size at the center of the prepared ingot consistently matches it at the edge. Finite element analysis confirms that low-flow pouring provides suitable thermal conditions for ensuring homogenous grains. Additionally, based on experimental results, a novel analytical model is proposed to precisely identify all active nucleation substrates. The grain size predicted by the proposed model aligns well with the experimental results, outperforming previous models. Our experimental and analytical results provide valuable guidance for the production of homogeneous ingots on an industrial scale.

A machine learning-based alloy rapid design system (ARDS) was proposed to customize the preparation strategies for the desired properties or predict the alloy properties following the preparation strategies. For achieving this, three regression algorithms: linear regression (LR), support vector regression (SVR), and back propagation neural network (BPNN), were employed separately to train the multi-property prediction model, in which the machine learning (ML) model built using SVR was proved to be the best. Then, inspired by the generative adversarial network (GAN) algorithm, the ARDS was constructed. The predictive reliability of ARDS was examined, and for the accurate prediction of the preparation strategies, the upper limits of ultimate tensile strength (UTS), yield strength (YS), and elongation (EL) are about 790 MPa, 730 MPa, and 28%, respectively. Moreover, an ARDS-designed aluminum alloy with superior mechanical properties (764 MPa for UTS, 732 MPa for YS, and 10.1% for EL) was experimentally fabricated, further verifying the reliability of ARDS.

The interfacial lattice mismatch and local elastic strains of Al/TiB2 heterostructures are quantitatively investigated by aberration-corrected transmission electron microscopy. Both in-plane atomic expansion and out-of-plane compression of Al layers stacked on (0001)TiB2 are uncovered and favor the further extension of deformed Al layers for realizing a successfully heterogeneous nucleation. These lattice strains can persist up to several Al atomic layers from the topmost (0001) surface of TiB2. Based on the compressive and expansive elastic strain relation, we estimate the Poisson's ratio in Al nuclei and find that large mismatch strains lead to abnormal changes in the Poisson's ratio. This study reveals the effect of lattice mismatch on the heterogeneous nucleation of Al on TiB2 and may have important implications in understanding the heterogeneous nucleation of Al.

The development of the aviation industry is accompanied by the continuous research of high-performance aviation aluminum alloys. Stuck in vast untapped composition space and the routine trial-and-error method, efficiently discovering high-strength aluminum alloys remains a significant challenge. To address this issue, we proposed a knowledge-aware design system (KADS) using machine learning (ML) methods to facilitate the rational design of high-strength aviation aluminum alloys. An aviation aluminum alloy database containing 5113 samples was built based on Al–Zn–Mg–Cu, Al–Cu, and Al–Li series aluminum alloys. Notably, guided by the material knowledge, we constructed a feature pool (23 descriptors) to improve the interpretability and accuracy of ML models. Taking key knowledge-aware features as input, we realized the transformation from “element content to property” to “material knowledge to property” in ML modeling, which is the first time proposed in aviation aluminum alloys design. According to the predictive results, we experimentally fabricated a KADS-designed aluminum alloy (KADS-Sc) with superior mechanical strength (812 MPa for ultimate tensile strength and 792 MPa for yield strength). Furthermore, the strengthening mechanisms in KADS-Sc alloy were established quantitatively. The calculations confirmed that the precipitation strengthening (≈ 439 MPa) was most critical in the final strength increment, agreeing with the microstructure analysis.

Hot-forming Quenching (HFQ) can lead to significant changes in microstructure of high-strength aluminum alloys for car body sheet. Furthermore, through effective control, desired performance of the alloys can be achieved. Three designed processes, HFQ + Natural Aging (NA) + Simulate Baking (SB), HFQ + Pre-aging (PA) + SB and HFQ + Peak-aging (T6) were applied in this work, and the evolution of precipitated phases was sys-tematically studied using High Resolution Transmission Electron Microscopy-Selected Area Electron Diffraction (HRTEM-SAED). The results revealed the precipitation nature of eta phase in 7055 aluminum alloys is that GP zone I evolves into GP zone II, on which eta' phases directly nucleate and multiply, resulting in the transformation from eta' phases into eta phases. By comparing the three processes, it is found that HFQ + PA + SB has high-density and finely distributed eta' phases, and grain boundary precipitates are small and discontinuously distributed. By adjusting the pre-aging temperature and time, it can provides a large amount of precipitation nucleation basis for the baking stage and ensure that eta' phase formation with high quantity density. The end product has a tensile strength of 660.1 MPa and a yield strength of 639.4 MPa, which is the most promising sheet material for future car body application.

The influence of polycarbosilane (PCS) content on the macroscopic appearance, microstructures and tensile properties of particles reinforced nickel matrix composites (PRNMCs) fabricated via in-situ polymer-derived particles (PDPs) method was studied. The method to decide suitable addition of polymer was proposed. It is revealed that the suitable content of PCS to obtain an intact PRNMCs is 1.24- 8.31 wt%, which is decided by the density of raw materials, volume elastic aftereffect of green compact and the volume fraction of interparticle gaps in green compact under pressing. The formation and evolution of amorphous SiO2 and lamellar graphite particles in PRNMCs with different PCS contents have been clarified. With increasing PCS content, the content of amorphous SiO2 particles beneficial to improve the strength and ductility of Ni-PCS composites keeps stable. However, the number and size of lamellar graphite particles harmful to tensile properties are acceleratedly increased. These results provide guide to designing high performance PRNMCs by in-situ PDPs method.

For patients with EGFR/HER2 exon20 insertion mutations, platinum-containing double-drug chemotherapy is still the standard treatment method. First-generation TKIs have almost no therapeutic activity against 20 insertions. The efficacy of second-and third-generation TKIs is still controversial. These patients urgently need more effective treatment regimens, and combination with immunotherapy or anti-angiogenic therapy could be a new breakthrough.

Titanium diboride (TiB2) is an effective grain refiner of Al alloys in the industry that facilitates casting processes by forming uniformly refined microstructures. Although our understanding of the underlying refinement mechanisms has advanced, the atomic kinetics of heterogeneous nucleation of Al on TiB2 remains unknown. Here, we report atomic-scale observations of the heterogeneous nucleation and growth kinetics of Al on self-formed TiB2 particles by in situ heating of undercooled Al-5Ti-1B films. We demonstrate that an ordered Al monolayer forms on the Ti-terminated {0001}TiB2 surface; then, the surrounding Al atoms are initiated to form an island-shaped Al nucleus with face-centered cubic {111} stacking without the assistance of a Ti-rich buffer layer. The interfacial lattice mismatch between {111}Al and {0001}TiB2 causes remarkable out-of-plane strain that decreases gradually with Al nucleus layers increasing to 6 atomic layers. The elastic strain energy originating from this interfacial strain increases the free energy of the Al/TiB2 heterostructure, hence impeding the rapid growth of the Al nucleus. We found that TiB2 particles stabilize the Al nuclei rather than activating their free growth into grains when the experimental undercooling ΔT is lower than the onset undercooling ΔTfgin Greer's free growth model. Our findings provide an atomic-scale physical image of the heterogeneous nucleation and growth mechanisms of Al with inoculator participation and elucidate the strain-dependent growth kinetics of Al nuclei.

Strength and ductility of structural materials are mutually exclusive in general due to the strength-ductility trade-off. Using in-situ pyrolysis of polycarbosilane in NiCr powder green compacts, we fabricated NiCr-based composites with micro-sized crystalline Cr3C2 and amorphous SiO2 dual-particles. Tensile tests show that the NiCr-based composites have a combination of high strength and ductility with the yield strength, ultimate tensile strength and ductility as 449 MPa, 838 MPa and 20.5%, respectively. The amorphous SiO2 and crystalline Cr3C2 particles exhibit plastic deformation and transgranular fracture, respectively, under tensile stress. Besides solid solution strengthening, the generation and annihilation behavior of dislocations at amorphous/crystalline interface and the strain hardening of the ceramic particles by hindering the movement of dislocations mutually contributes to the combination of excellent strength and ductility of our composites.

Pressure, analogous with temperature and composition, is other meaningful variant for tuning the structure-activity properties of layered materials. In-situ high-pressure electrical results discover that Vanadium based MXene (V2CTx MXene) conductivity is increased by one order of magnitude from ambient to 10.4 GPa, and then the conductivity is still fixated on meeting growth as pressure releasing. Increased carrier concentration due to denser compactness is the most important factor in improving sample conductivity. Furthermore, abundant of V2CTx samples after preloading different pressures are prepared by the mean of the double-anvil hydraulic press for the first time, and results of increased conductivity were reproduced at ambient conditions. The first-principles calculation of V2C (non-functional group), V2CF, V2CO, and V2COH explains for the lattice expansion by tracing emotion of different function groups upon decompression. Electrochemical results obtain that once forming V2CTx MXene anode rapidly quenched from 2.0 GPa in hydraulic press shows better performance, obviously weakening electric polarization and increasing Li-ion transport rate due to its proper interlaminar densification and improved conductivity. This work opens up a new, simple, and universal approach to develop MXene materials with superior electrical and electrochemical properties, as well as expanding the potential applications for energy storage.

Microstructures and mechanical properties of Ni matrix composites reinforced with amorphous SiO2 particles by in-situ pyrolysis of polycarbosilane (PCS) coated on Ni powders were studied in this paper. The submicron spherical amorphous SiO2 particles instead of traditional SiC uniformly distributing in the composites result from the generated silicon source by PCS pyrolysis combined with oxygen impurity in the preparation. The prepared composites achieve high yield strength, 172 MPa, and ultimate tensile strength, 494 MPa, as well as outstanding ductility, total elongation 28.4 %, which is improved 13.9 %, 50.6 % and 160.6 % compared with those for pure Ni samples, respectively. The effects of solid solution strengthening, grain refinement strengthening, reinforcement particle strengthening and dislocations behavior of at amorphous/ crystalline interface on the combination of high strength and ductility of the composites were discussed.& COPY; 2023 Elsevier B.V. All rights reserved.