The impact of Fe content on the microstructures and mechanical properties of an ultra-high strength aluminum alloy, namely, Al−10.50Zn−2.35Mg−1.25Cu−0.12Cr−0.1Mn−0.1Zr−0.1Ti, was investigated. It is found that the increase of Fe content leads to a notable rise in the volume fraction of microscale secondary phases, including (Cu,Fe,Mn,Cr)Al₇, σ phase (composed of Al, Zn, Mg, and Cu elements), and Al₃(Zr,Ti). The formation of these secondary phases results in the depletion of certain phase-forming elements, thereby significantly reducing the quantity of strengthening phases. Fe imposes minimal impact on tensile strength, but it can significantly alter the elongation (δ). For instance, the average elongation of the alloy with 0.18 wt.% Fe (δ=4.5%) is less than half that of the alloy with Fe less than 0.1 wt.% (δ=9.9%−10.9%). The reduction in elongation is attributed to the combined effects of the formation of coarse secondary phases and the diminished quantity of strengthening phases around these coarse phases.

The corrosion resistance and mechanical properties of peak-aged AlZnMgCu alloys containing Si and Er elements were investigated with hardness test, tensile test, intergranular corrosion test, exfoliation corrosion test and transmission electron microscopy. The results indicate that peak-aged AlZnMgCuSiEr alloy is strengthened by co-precipitation of η′ phases and nano-sized GPB-II zones. The yield strength of the AlZnMgCu alloy is increased by 38.5 MPa and the elongation is increased by 4.5%. At the same time, the corrosion resistance of the AlZnMgCuSiEr alloy is enhanced due to the synergistic effect of Er and Si. The maximum intergranular corrosion (IGC) depth decreases from 264.2 to 9.9 μm. The fundamental reason is that the co-addition of Si and Er regulates the evolution of precipitated phases in grains and at grain boundaries.

1060/7050 Al/Al laminated metal composites (LMCs) with heterogeneous lamellar structures were prepared by accumulative roll bonding (ARB), cold rolling and subsequent annealing treatment. The strengthening mechanism was investigated by microstructural characterization, mechanical property tests and in-situ fracture morphology observations. The results show that microstructural differences between the constituent layers are present in the Al/Al LMCs after various numbers of ARB cycles. Compared with rolled 2560-layered Al/Al LMCs with 37.5% and 50.0% rolling reductions, those with 62.5% rolling reductions allow for more effective improvements in the mechanical properties after annealing treatment due to their relatively high mechanical incompatibility across the interface. During tensile deformation, with the increased magnitude of incompatibility in the 2560-layered Al/Al LMC with a heterogeneous lamellar structure, the densities of the geometrically necessary dislocations (GNDs) increase to accommodate the relatively large strain gradient, resulting in considerable back stress strengthening and improved mechanical properties.

The microstructure and texture evolutions during extrusion and rolling processes of the 2195 Al−Li alloy were investigated. The EBSD technique was employed to reveal the microscopic evolution mechanisms of different texture components. The findings reveal that the texture evolution is governed by two mechanisms: an overall orientation transformation induced by plastic strain and a localized transformation occurring at the shearing bands within grains. During the rolling process, the extrusion texture components of Ex  and Cu  evolve into S , and the Bs  rotates into the orientations near R-Bs and S. With increasing deformation, the S, Bs, and R-Bs orientations further rotate around the TD axis and disperse into new orientations, forming recrystallized grains. The shearing bands with different initial orientations exhibit similar orientation evolution patterns, all of which evolve from the initial orientation to a series of recrystallization orientations.

To obtain lightweight multicomponent magnesium alloys with high tensile strength, ductility, and stiffness, two extruded Mg_92−5xAl_1.5+3xZn₃Cu_3.5+xCe_x (x=0.5 and 1, labeled as C0.5 and C1) alloys were designed. The results reveal that the ultimate tensile strength, yield strength (YS), and fracture strain of the C0.5 alloy are simultaneously improved compared to those of the C1 alloy, with values of 346 MPa, 312 MPa, and 11.7%, respectively. This enhancement is primarily attributed to the refinement of numerous secondary phases (micron scale Al₃CuCe, micron scale MgZnCu, and nanoscale MgZnCu phases). The calculation of YS shows that the Orowan strengthening and coefficient of thermal expansion mismatch strengthening are the main strengthening mechanisms, and the contribution values of both to the YS are 28 and 70 MPa for C0.5 alloy. In addition, the C0.5 alloy has a greater plasticity than the C1 alloy because the ác+añ slip system is initiated.

A method of pre-regulating the lamellar long-period stacking ordered (LPSO) phase was introduced to enhance the hot plasticity of rare earth magnesium alloys. Additionally, low-temperature extrusion was used to achieve a comprehensive improvement of alloy performance with small deformation, providing a new approach for the preparation of high-performance large components. The strengthening−toughening mechanism under low-temperature extrusion with an extrusion ratio of 3.6꞉1 was investigated by comparing the microstructure and performance of pre-regulated Mg−Gd−Y−Zn−Zr alloy at three different extrusion temperatures (420, 450, and 480 °C). Results show that the alloy extruded at 420 °C exhibits a yield strength of 341 MPa, tensile strength of 419 MPa, and elongation of 7.2%. The increase in strength is mainly caused by the strong texture and internal dislocation pinning of the undynamic recrystallization (un-DRX) zone, and a lower volume fraction of β dynamic precipitation phase is beneficial to improving the ductility of the alloy.

The effect of extrusion temperature on the dynamic recrystallization behavior and mechanical properties of the flame-retardant Mg−6Al−3Ca−1Zn−1Sn−Mn (wt.%) alloy was investigated. The observed dynamic recrystallization mechanisms in the alloy include continuous dynamic recrystallization (CDRX) and particle simulated nucleation (PSN) during hot extrusion. A significant increase in yield strength, from 218 to 358 MPa, representing a 140 MPa increase, is achieved by decreasing the extrusion temperature. The strengthening mechanisms were analyzed quantitatively, with the enhanced strength primarily attributed to grain boundary and dislocation strengthening. The plasticity mechanism was analyzed qualitatively, and the increase in the volume fraction of unDRXed grains caused by the decrease in extrusion temperature leads to an increase in the number of  tensile twins during the tensile deformation, resulting in a reduction in plasticity.

With the aim of improving the fatigue properties of Mg alloy welded joints under cyclic loading, the effects of laser bionic treatment and ultrasonic impact bionic treatment on the fatigue crack growth (FCG) behavior of AZ31B Mg alloy TIG-welded joints were studied and compared. The results show that bionic treatment refines the grains on the joint surface and improves the microhardness. In the crack stable growth stage, both bionic samples exhibit a lower FCG rate and a higher FCG resistance. The two bionic treatment methods reduce the probability of crack initiation and partially promote crack deflection, providing a new approach for improving the FCG behavior of welded joints.

The microstructure and creep behavior of C/Y₂O₃ synergistically micro-alloyed high-Al and low-Al TiAl alloys prepared by induction skull melting (ISM) technology were investigated by advanced electron microscopy. Microstructure analysis shows that Y₂O₃ particles are dispersed in both alloys; element C is dissolved in low-Al alloys as solid solution, while it exists as Ti₂AlC particles within lamellae in high-Al alloys. Additionally, high-density nanotwins are generated in high-Al alloys. Creep data show that C/Y₂O₃ micro-alloying significantly enhances creep resistance of TiAl alloys. This benefits from the dispersion strengthening of Y₂O₃ particles, precipitation hardening of dynamically precipitated Ti₃AlC particles and lamellar stabilization caused by dissolved C atoms or Ti₂AlC particles. This strategy causes a more significant improvement on creep resistance of high-Al TiAl alloys, which is attributed to extra twin strengthening effect. At 775−850 °C, these alloys fracture in mixed ductile−brittle mode, but the fracture characteristics change with the increase of temperature.

Compressive mechanical behavior and microstructure evolution of Ti−5.7Al−2.9Nb−1.8Fe−1.6Mo− 1.5V−1Zr alloy under extreme conditions were systematically investigated. The results show that strain rate and temperature have a significant influence on the mechanical behavior and microstructure. The alloy exhibits a positive strain rate sensitivity and negative temperature sensitivity under all temperature and strain rate conditions. The hot- rolled alloy is composed of a bimodal structure including an equiaxed primary α_p phase and a transformed β phase. After compression deformation, the bimodal deformed structural features highly rely on the temperature and strain rate. At low temperature and room temperature, the volume fraction and size of α_p phase decrease with increasing temperature and strain rate. At high temperature, the volume fraction of the α phase is inversely correlated with temperature. A modified Johnson−Cook constitutive model is established, and the predicted results coincide well with the experimental results.

A unique discontinuous lamellar microstructure of titanium alloys consisting of lamellar colonies at prior β-Ti grain boundaries and internal interwoven α-laths is prepared by a TiH₂-based powder metallurgy method. The α-variants get various crystallographic orientations and become discontinuous during vacuum annealing at 700 °C. Remarkably, nanoscale phase δ-TiH compound layers are generated between α-laths and β-strips, so that dislocations are piled up at the α/δ/β interfaces during tensile deformation. This leads to dislocation slips being confined to individual α-laths, with different <a> slips and particularly pyramidal <c+a> slips being activated. The efficiency of wavy slip is promoted and the work hardening rate is enhanced. Finally, the combined effect of dispersed micro-shear bands and lath distortions is considered contributive for alleviating the stress concentration at grain boundaries, resulting in a high-promising synergy of enhanced ultimate tensile strength of 1080 MPa and good elongation to fracture of 13.6%.

To assess the high-temperature creep properties of titanium matrix composites for aircraft skin, the TA15 alloy, TiB/TA15 and TiB/(TA15−Si) composites with network structure were fabricated using low-energy milling and vacuum hot pressing sintering techniques. The results show that introducing TiB and Si can reduce the steady-state creep rate by an order of magnitude at 600 °C compared to the alloy. However, the beneficial effect of Si can be maintained at 700 °C while the positive effect of TiB gradually diminishes due to the pores near TiB and interface debonding. The creep deformation mechanism of the as-sintered TiB/(TA15−Si) composite is primarily governed by dislocation climbing. The high creep resistance at 600 °C can be mainly attributed to the absence of grain boundary α phases, load transfer by TiB whisker, and the hindrance of dislocation movement by silicides. The low steady-state creep rate at 700 °C is mainly resulted from the elimination of grain boundary α phases as well as increased dynamic precipitation of silicides and α₂.

Laser specific energy significantly impacts the quality of composite coatings. Ti−Al/WC coatings were prepared on the TC21 alloy through laser cladding with specific energy ranging from 66.7 to 133.3 J/mm². The results indicate that the composite coatings primarily comprised Ti₂AlC, α₂-Ti₃Al, γ-TiAl, TiC, and W phases. A gradual increase in the relative intensity of the diffraction peaks of Ti₂AlC, α₂-Ti₃Al, and TiC appeared with the increase of specific energy. When the specific energy was 116.7 J/mm², the Ti−Al/WC coated alloy achieved a maximum micro- hardness of HV_0.2 766.3, which represented an increase of 1.96 times compared with TC21 alloy, and the minimum wear rate decreased dramatically. Much improvement in tribological properties was attained through the fine-grained strengthening of the (α₂+γ) matrix and the dispersion strengthening of self-lubricating Ti₂AlC and intertwining TiC. This study provides valuable insights for the development of high-performance Ti−Al composite coatings.

This study devoted to optimize the laser powder bed fusion (LPBF) parameters for the preparation of Zr−2.5Nb alloys, and was focused on power of incident laser beam and its scanning speed. The microstructure, mechanical and corrosion properties of samples prepared at different laser powers were investigated. The results show that high quality samples were obtained with the relative density over 99%, ultimate tensile strength of 980 MPa, and the elongation at fracture of 14.18%. At a scanning speed of 1400 mm/s, with increasing laser power from 120 to 180 W, two transformation processes: α' martensite coarsening and transition from an acicular into a zigzag structure (β→α'/α→α+β) occurred. Densification and α' martensite transition improved ductility and corrosion resistance at optimal value of the laser power while lower or higher laser power resulted in decreasing the ductility and corrosion resistance because of unfused particles and pores. Increasing β-Zr amount and size decreased the tensile strength due to the dislocation movement. Passive films, which were spontaneously formed at different laser powers, possessed an optimum corrosion resistance at the laser power of 160 W.

To explain the precipitation mechanism of χ phase in Co-based superalloys, the microstructural evolution of Co−Ti−Mo superalloys subjected to aging was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the needle-like χ phase is mainly composed of D0₁₉-Co₃(Ti,Mo), which is transformed from L1₂-γ′ phase, and a specific orientation relationship exists between them. χ phase is nucleated through the shearing of γ′ phase due to the influence of stacking fault. The crystal orientation relationship between L1₂ and D0₁₉ can be confirmed as {111}_L12//{0001}_D019, and . The growth of D0₁₉-χ phase depends on the diffusions of Ti and Mo, and consumes a large number of elements. This progress leads to the appearance of γ′ precipitation depletion zone (PDZ) around D0₁₉-χ phase. The addition of Ni improves the stability of L1₂-γ′ phase and the mechanical properties of Co-based superalloys.

Insufficient metallurgical compatibility between Zr and Ni can lead to the formation of brittle welds and introduce thermal stress-related challenges during the electron beam welding process. Through the implementation of beam deflection and vibration, a transformation was achieved in the primary Ni₅Zr dendrite structure, transitioning from a mass into a layered configuration, consequently resulting in the formation of an ultrafine-grained eutectic−dendrite complex structure. It is revealed that the enhanced strength−ductility synergy of this structure significantly contributes to the high tensile strength and improved plasticity observed in the welded joints. As a result, the welding cracks are effectively mitigated, and notable advancements are achieved in the mechanical properties of Zr/Ni joints, elevating the tensile strength of the joints from 36.4 to 189 MPa. This research not only highlights the potential of this technique in enhancing the strength and ductility of Zr/Ni welded joints but also serves as a valuable reference for future investigations involving welding applications of dissimilar metals.

The novel core−shell SiC@CoCrFeNiMn high-entropy alloy (HEA) matrix composites (SiC@HEA) were successfully prepared via mechanical ball milling and vacuum hot-pressing sintering (VHPS). After sintering, the microstructure was composed of FCC solid solution, Cr₂₃C₆ carbide phases, and Mn₂SiO₄ oxy-silicon phase. The relative density, hardness, tensile strength, and elongation of SiC@HEA composites with 1.0 wt.% SiC were 98.5%,  HV 358.0, 712.3 MPa, and 36.2%, respectively. The core−shell structure had a significant deflecting effect on the cracks. This effect allowed the composites to effectively maintain the excellent plasticity of the matrix. As a result, the core−shell SiC@HEA composites obtained superior strength and plasticity with multiple mechanisms.

To modify the stable thermodynamics and poor kinetics of magnesium hydride (MgH₂) for solid-state hydrogen storage, MIL-100(Fe) was in situ fabricated on the surfaces of TiO₂ nano-sheets (NS) by a self-assembly method, and the prepared TiO₂ NS@MIL-100(Fe) presents an excellent catalytic effect on MgH₂. The MgH₂+ 7wt.%TiO₂ NS@MIL-100(Fe) composite can release hydrogen at 200 °C, achieving a decrease of 150 °C compared to pure MgH₂. Besides, the activation energy of dehydrogenation is decreased to 70.62 kJ/mol and 4 wt.% H₂ can be desorbed within 20 min at a low temperature of 235 °C. Under conditions of 100 °C and 3 MPa, MgH₂+7wt.%TiO₂ NS@MIL-100(Fe) absorbs 5 wt.% of H₂ in 10 min. Surprisingly, 6.62 wt.% reversible capacity is maintained after 50 cycles. The modification mechanism is confirmed that the presence of oxygen vacancies and the synergistic effect of multivalent titanium in TiO₂ NS@MIL-100(Fe) greatly enhance the kinetic and thermodynamic properties of MgH₂.

A method combining finite difference method (FDM) and k-means clustering algorithm which can determine the threshold of rock bridge generation is proposed. Jointed slope models with different joint coalescence coefficients  (k) are constructed based on FDM. The rock bridge area was divided through k-means algorithm and the optimal number of clusters was determined by sum of squared errors (SSE) and elbow method. The influence of maximum principal stress and stress change rate as clustering indexes on the clustering results of rock bridges was compared by using Euclidean distance. The results show that using stress change rate as clustering index is more effective. When the joint coalescence coefficient is less than 0.6, there is no significant stress concentration in the middle area of adjacent joints, that is, no generation of rock bridge. In addition, the range of rock bridge is affected by the coalescence coefficient (k), the relative position of joints and the parameters of weak interlayer.

The ion coordination affinities of the commonly found metal ions were evaluated using DFT calculations. The results indicate that the lowest unoccupied molecular orbital (LUMO) energy of metal ions correlates positively with their binding energies with O(S) ligands, and some metal ions with various valence states also present different affinities. Besides, due to the steric hindrance effects, the mono- and hexa-coordinated metal ions may exhibit different affinities, and the majority of the studied hexa-coordinated metal ions exhibit oxophilicity. These affinity differences perfectly illustrate the activation flotation practice in which the oxyphilic ions are applied to activating oxide minerals, while thiophilic ions are applied to activating sulfide minerals.

An approach for coal-based direct reduction of vanadium−titanium magnetite (VTM) raw ore was proposed. Under the optimal reduction conditions with reduction temperature of 1140 °C, reduction time of 3 h, C-to-Fe molar ratio of 1.2比1, and pre-oxidation temperature of 900 °C, the iron metallization degree is 97.8%. Ultimately, magnetic separation yields an iron concentrate with an Fe content of 76.78 wt.% and efficiency of 93.41%, while the magnetic separation slag has a Ti grade and recovery of 9.36 wt.% and 87.07%, respectively, with a titanium loss of 12.93%. This new strategy eliminates the beneficiation process of VTM raw ore, effectively reduces the Ti content in the iron concentrate, and improves the comprehensive utilization of valuable metals.

Secondary aluminum dross (SAD), a by-product of aluminum extraction from primary aluminum dross, contains metallic aluminum particles coated with dense oxidized films, complicating the recovery of metallic aluminum using traditional methods. Ball-milling was employed to break and alter the structure of these oxidized films. The results indicated that the films became thinner and stripped away, exposing the aluminum surface. Based on the in-situ observation of the structure evolution of milled SAD particles with temperature, the metallic aluminum liquid was efficiently recovered from SAD at 680 °C via supergravity-enhanced separation, where the recovery ratio and mass fraction of Al in the separated aluminum phase were up to 95.72% and 99.10 wt.%, respectively. Moreover, the tailings can be harmlessly utilized in refractory, cement and ceramic fields with subsequent treatment, such as denitrification, dechlorination, and fluoride fixation.

The erosion process and kinetics of PbTe particles in a selenium melt were investigated. The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical reaction at low temperatures (573, 583, and 593 K), but the limiting step is controlled by boundary layer diffusion at high temperatures (603 and 613 K). The Se- and Te-atom diffusion in the product layer becomes unbalanced as the product layer thickens, with Kirkendall voids generating in the product layer accelerating PbTe particle erosion. After the PbTe impurities in the selenium melt evolve into PbSe and Te, Te is evenly distributed in the selenium melt owing to the solubility of Se and Te. This study serves to clarify the evolution behavior of PbTe impurities in the selenium melt and the reason that Te often occurs in Se.

A sustainable approach for recovering battery grade FePO₄ and Li₂CO₃ from Al/F-bearing spent LiFePO₄/C powder was proposed, including acid leaching, fluorinated coordination precipitation, homogeneous precipitation, and high-temperature precipitation. Under the optimal conditions, the leaching efficiencies of Li, Fe, P, Al, and F were 97.6%, 97.1%, 97.1%, 72.5%, and 63.3%, respectively. The effects of different parameters on the removal of Al/F impurities were systematically evaluated, indicating about 99.4% Al and 96.4% F in the leachate were precipitated in the form of Na₃Li₃Al₂F₁₂, and their residual concentrations were only 0.0124 and 0.328 g/L, respectively, which could be directly used to prepare battery grade FePO₄ (99.68% in purity). Lithium in the Al/F-bearing residue could be extracted through CaCO₃−CaSO₄ roasting followed by acid leaching, ultimately obtaining 99.87% purity of Li₂CO₃. The recovery rates of Li and Fe were 96.88% and 92.85%, respectively. An economic evaluation demonstrated that the process was profitable.