The impact of selective laser melting (SLM) and direct aging (DA) heat treatment on the microstructure and mechanical properties of AlSi10Mg alloys was investigated. Microstructural characterization using SEM and EBSD revealed that SLM alloys exhibited a fine-grained cellular structure with α(Al) and Si-enriched phases, whereas cast alloys displayed a coarse eutectic Si morphology. Subsequent DA treatment demonstrated a 9.24% higher yield strength and a 5.56% improvement in ultimate tensile strength of the DA-B AlSi10Mg alloy when compared to the non-heat-treated alloy (NHT-AB), indicating significant improvements due to the DA process. Fracture surface analysis indicated predominantly ductile fracture in SLM alloys, contrasting with mixed ductile−brittle behavior in cast samples. Furthermore, EBSD texture analysis indicated a grain elongation in necked regions of SLM alloys after tensile deformation. The precipitation strengthening significantly contributes to the enhanced strength of the SLM alloys followed by the cell boundary strengthening. These findings highlight the potential of SLM and DA for producing high-performance AlSi10Mg components for aerospace, automotive, and rapid prototyping applications.

Texture and grain structure evolution during annealing and their effects on tensile strength and anisotropy were studied using XRD, DSC, SEM, EBSD and TEM. The results indicate that elevated rolling temperatures reduce       the f(g)_max(Copper)/f(g)_max(Brass) ratio, increase S−Brass fine bands, and promote S-dispersoid precipitation, leading to finer recrystallized grains. Dominant recrystallization textures transform from Goss + P to Goss and then to Goss + Cube with increasing rolling temperature. Annealing at 350 ℃ shows four tensile strength response stages: fast softening I, rapid strengthening II, slow strengthening III, and slow softening IV. The transition from Stages I to II is driven by the formation of strong Goss and P textures, and Stage IV is linked to enhanced Cube texture. Plates with Goss + Cube textures and fine equiaxed grains exhibit the lowest YS/UTS ratio and minimal anisotropy.

A novel method called thermomechanical treatment based on impact hydroforming (TTIHF) was proposed. The pre-deformation was achieved by using impact hydroforming (IHF) loading. The strengthening effect and mechanism of 2195 Al−Li alloy were investigated under various loading pre-deformation conditions. The results showed that the time for the alloy to reach peak aging was shortened under TTIHF. Compared with those of the pre-deformation method of stamping forming, the yield strength and tensile strength of the Al−Li alloy under TTIHF increased by 18.6% and 18.0%, respectively. The deformation caused by IHF loading resulted in a high density of dislocations, which served as nucleation sites for the precipitation of the T₁ phase during aging. After TTIHF, the average diameter and thickness of the T₁ phase in the alloy were smaller than those under other experiment conditions. Moreover, the density and distribution of the T₁ phase were the highest and the most uniform.

The microstructure and mechanical properties of ZK60 extruded alloy by rapid solidification (RS) and as-cast ingot processes were investigated using optical microscope, scanning electron microscope, X-ray diffraction, electron back-scatter diffraction, and mechanical tests. The results show that the RS ZK60 extruded alloy exhibits relatively high tensile yield strength (TYS), compressive yield strength (CYS) and elongation of 300.8 MPa, 303.6 MPa and 18.6%, respectively. The RS ZK60 extruded alloy with an ultra-fine grain size of 1.28 μm not only has a weak texture with a maximum polar density of 3.3 but also addresses the tension−compression asymmetry with a CYS/TYS ratio of approximately 1.0. The calculation of the strengthening mechanism indicates that the improvement in the mechanical properties of the RS ZK60 extruded alloy is primarily attributed to grain refinement.

To investigate the complex relationship between rolling process parameters and mechanical properties of AZ31 magnesium alloy rolled sheets, the Leave-One-Out Cross-Validation (LOOCV) and parameter tuning were applied to optimizing hyper-parameters for the four (BPNN, SVR, RF, and KNN) machine learning models. An interpretable prediction model based on machine learning and SHapley Additive exPlanations (SHAP), as well as an analytical method combining the SHAP model and the Pearson Correlation Coefficient (PCC), were proposed. The results showed that among the four models, the SVR model was able to simultaneously and accurately predict the ultimate tensile strength (UTS) and elongation (EL). According to the combination analysis of PCC and the magnesium alloy rolling forming mechanism, it was found that strain rate and reduction displayed a negative and positive correlation with UTS, respectively, while rolling temperature and reduction illustrated a positive and negative correlation with EL, respectively. Through the SHAP method, which could interpret the output results of the SVR machine learning model, it was deduced that reduction and strain rate played an important role in the SVR model of the outputs of the UTS and EL, respectively. Combining SHAP with PCC, it was found that strain rate and reduction had a greater influence on the UTS than rolling temperature, whereas strain rate and rolling temperature had more influence on the EL compared to reduction.

The elimination of the B2 phase in a β-solidifying high Nb-containing TiAl alloy with β/B2 and γ phases was investigated using different heat treatments, with a focus on understanding the phase transformations and lamellae formation during the process. The phase transformation and lamellae formation during B2 phase elimination differs from that observed in conventional TiAl alloys. During the holding stage of heat treatment, the β/B2 phase is replaced by the α phase through primary phase transformations of β→α and γ→α. Lamellae formation occurs within both α and γ grains during cooling, initiating 30−40 °C below the annealing temperature. This lamellar structure was formed via two main mechanisms: nucleation at grain boundaries followed by growth into the grain, and direct precipitation and growth within the grain. The orientation relationship between the γ phase and its adjacent α phase is (111)_γ//(0001)_α and , with a coherency between the phases characterized by a misfit of approximately 1.7%.

To investigate the evolution of grain orientation and slip modes in magnesium alloys with multiple texture components, an AZ31 gradient-structured magnesium alloy sheet was fabricated using hard plate rolling (HPR). The changes in texture and slip modes under different reductions were examined. The results demonstrate that the AZ31 magnesium alloy sheets display a self-epitaxial gradient structure, with the best mechanical properties observed at rolling temperature of 673 K and reduction of 50%. Significant changes in texture type and strength are observed along the normal direction (ND) of the sheet. The coarse-grain region exhibits a bimodal texture aligned with the rolling direction. These texture variations enhance the stress distribution at the fine grain−coarse grain interface, influencing the grain orientation and the activation of different slip modes, thus improving the mechanical properties of gradient-structured magnesium alloy sheets. This approach offers a new strategy for the fabrication of high-performance magnesium alloy sheets.

The transformation of the dissimilar metals in the welding area into a single metal is an important method for achieving high-quality welded connection in the dissimilar metal laminated composite plate. In this study, a high-performance titanium/steel composite plate (TSCP) with pure titaniumization in the welding area was prepared by cold spraying, hot rolling and heat treatment processes. The results indicate that cold spraying achieves effective pre-composite deposition of titanium particles while inhibiting interfacial oxidation and Fe−Ti alloying reactions, producing a relatively dense pure titanium coating with a low porosity of only 1.2%. Hot rolling eliminates internal defects and promotes strong metallurgical bonding of the composite interface. The heat treatment promotes the recrystallization and reduces the dislocation density within the coating. The interfacial bonding strength of the welding area with pure titaniumization of TSCP is 257 MPa, and the tensile strength of that is 414 MPa, reaching 95.6% of the TSCP’s base material.

Inconel 625 alloy components were fabricated using hot wire laser metal deposition (HW-LMD) through process optimization, achieving a wire deposition rate of 1.72 kg/h. The microstructure and mechanical properties of the HW-LMD Inconel 625 alloys were systematically investigated. The results revealed that the microstructure of the HW-LMD Inconel 625 alloys consisted of columnar dendrites, characterized by an average grain size of 12.5 µm and a strong {100}<001> texture. The main phase identified was γ-Ni, with the precipitation of Laves phase, measuring less than 1 μm, observed in the inter-columnar dendritic regions. The average microhardness of the HW-LMD Inconel 625 alloys was HV_1.0 258. The yield strength and ultimate tensile strength were 493.5 and 837.4 MPa, respectively, with elongation exceeding 50%. Impact absorbing energies at 25 and −78 °C were 223.08 and 200.24 J, respectively. Both the tensile and impact fracture surfaces exhibited dimples, indicating a ductile fracture mechanism during the deformation process.

To achieve high strength in Ni−Co-based wrought superalloys, cold-rolling was introduced into the solution and aging treatments. The alloys were characterized and tested using EBSD, SEM, TEM, and tensile tester to analyze their microstructure and mechanical properties at different temperatures, revealing their strengthening and deformation mechanisms. Results indicated that after solution, cold-rolling, and double aging, the alloy contained high-density dislocations, stacking faults, Lomer−Cottrell locks, and nanotwins. The yield strengths of the alloy at room temperature, 923, and 1023 K were 1855, 1406, and 1086 MPa, respectively, which were significantly higher than those of typical Ni-based wrought superalloys. This enhancement was primarily attributed to the dislocations and nanotwins. Additionally, during the cold-rolling process, plastic deformation mainly occurred through dislocation slip. With the temperature increasing to 923 and 1023 K, the main deformation mechanisms of the alloy transformed to stacking faults and nanotwins, respectively.

The deformation characteristics and activation mechanisms of kink bands in refractory multi-principal element alloys with local chemical fluctuations (LCFs) were systematically studied. These alloys were fabricated using laser-directed energy deposition technology and characterized by room-temperature compression testing, electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and high-angle annular dark-field (HAADF) imaging. The results reveal that kinking is a gradual rotational diffusion process, during which the misorientation difference between the kink and the matrix varies. A low Schmid factor is a prerequisite for kink excitation. The slip system closest to the loading axis is passively activated by the applied external force, leading to the accumulation of geometrically necessary dislocations (GNDs) required for lattice rotation. The widespread LCFs within the matrix reduce the migration rate of edge dislocations, promoting GND accumulation and enhancing the propensity for kink band formation. During deformation, the occurrence of kinking enables continuous lattice rotation to accommodate the exceptionally high strain in the vicinity, when the stress concentration in the primary kink cannot be fully released, double kinks are activated to reduce strain energy.

A fine-grained metastable dual-phase Fe₄₀Mn₂₀Co₂₀Cr₁₅Si₅ high entropy alloy (CS-HEA) with excellent strength and ductility was successfully prepared by friction stir processing (FSP). The microstructural and mechanical properties of the fine-grained CS-HEA were characterized. The results showed that as-cast shrinkage cavities and elemental segregation were eliminated. The average grain size was refined from 121.1 to 5.4 μm. The face-centered cubic phase fraction increased from 23% to 82%. During tensile deformation, dislocation slip dominated at strains ranging from 5% to 17%, followed by transformation induced plasticity (TRIP) from 17% to 26%, and twin induced plasticity (TWIP) from 26% to 37%. The yield strength, ultimate tensile strength, and elongation of the fine-grained CS-HEA were 503 MPa, 1120 MPa, and 37%, respectively. The strength−ductility synergy of fine-grained CS-HEA was attributed to the combined effects of TRIP, TWIP, dislocation strengthening, and fine-grained strengthening.

To address the zero-sample challenge in preparation parameter design for newly developed alloys, a novel machine learning strategy that integrates basic dataset construction with Bayesian optimization, was proposed. The impact of basic sample dataset construction methods, optimization benchmarks and multi-objective utility functions on Bayesian optimization was investigated. It was found that the combination of orthogonal design, linear benchmark, and shifted multiplicative utility function exhibits the best optimization performance. The strategy was then applied to a new Cu−Ni−Co−Si alloy with ultra-low Co content (0.7 wt.% Co), previously designed by our research team. Rapid optimization of six preparation parameters in the two-stage deformation and aging process of the zero-sample alloy was achieved through only 23 experiments. The measured ultimate tensile strength and electrical conductivity of the new alloy were 878 MPa and 44.0%(IACS), respectively, reaching the comprehensive performance level of the Cu−Ni−Co−Si alloy (C70350 alloy) containing 1.0−2.0 wt.% Co.

A Cu−1.9Ni−1.9Co−0.9Si (mass fraction, %) alloy with high strength and electrical conductivity was designed by cluster formula approach. The microstructure evolution of the alloy during thermomechanical treatment was systematically investigated. The strengthening mechanism and electrical conductivity of the alloy were discussed in detail. The optimal thermomechanical treatment process was as follows: solid solution → 80% cold rolling → (450 °C, 4 h) aging → 50% cold rolling → (400 °C, 4 h) aging. The designed alloy achieved excellent comprehensive properties with a microhardness of HV 260, a yield strength of 843 MPa, a tensile strength of 884 MPa, and an electrical conductivity of 42.6%(IACS). Compared to direct aging treatment, the designed alloy subjected to multi-stage thermomechanical treatment had refined grains, high density of dislocations, and accelerated of precipitation of (Ni,Co)₂Si precipitates. High strength was mainly attributed to the combined effect of dislocation strengthening, work hardening and sub-grain strengthening, while good electrical conductivity was maintained through the precipitation of the large number of nanoparticles.

The effect of warm rolling temperature (500−900 °C) on the microstructure and mechanical properties was investigated for a Ni−W−Co−Ta alloy to achieve excellent strength−plasticity synergy. The results showed that the alloy exhibited high-density dislocations and deformation bands when rolled below 750 °C. The nano-Ni₄W phase precipitated when rolled at 700−900 °C, with the higher deformation temperature, the amount and size of precipitates increased. At 900 °C, dissolution of the precipitated Ni₄W and dynamic recrystallization of the matrix occurred. Consequently, the strength and hardness firstly decreased, then increased, and decreased again as the deformation temperature increased. An excellent strength–plasticity synergy was achieved through the combined effects of precipitation strengthening and deformation twins strengthening of Ni₄W: with a tensile strength of 2010 MPa, a yield strength of 1839 MPa, a microhardness of HV 587, and an elongation of 13.2% when the alloy was warm-rolled at 750 °C.

The effects of γ-ray and electron irradiation on the microstructural evolution and mechanical properties of SnPb eutectic solder joints were investigated. Following electron irradiation, the SnO₂ phase induced by γ-ray irradiation transformed into β-Sn, and the dislocation density in the β-Sn crystal decreased. Moreover, numerous point defect clusters formed in the β-Sn crystal, some of which transformed into an amorphous phase, increasing the amorphous layer thickness. Meanwhile, electron irradiation likewise resulted in rotation of the (220) plane of β-Sn nanograins and reduction of SnO₂ in the β-Sn crystal. Additionally, upon exposure to γ-ray and electron irradiation, the average shear strength of the solder balls was initially increased by 10.10%, followed by a decrease of 3.53% and 4.77%, respectively. The plasticity and the dimple count on the fracture surfaces of the solder joint initially decreased but subsequently increased.

To improve the overall magnetic properties of Sm(CoFeCuZr)_z sintered magnets, a dual-alloy sintering process that involves mixing high-iron, low-copper powders with low-iron, high-copper powders was systematically investigated. The results demonstrate that this method significantly improves the Cu-lean phenomenon at the grain boundaries, achieves multiscale uniform microstructures, greatly enhances the pinning field strength, and ultimately produces a high-performance dual-alloy magnet with a maximum energy product ((BH)_max) exceeding 240 kJ/m³ and an intrinsic coercivity (H_cj) exceeding 2400 kA/m. In particular, when 35 wt.% of low-iron, high-copper alloy powder is incorporated, the dual-alloy magnet achieves a remanence of 1.13 T, H_cj of 2691.2 kA/m and (BH)_max of 248 kJ/m³. To evaluate the overall magnetic performance, the sum of H_cj (in kA/m) and (BH)_max (in kJ/m³) is used as a combined parameter, yielding a value of 2939.2. Compared with single-alloy magnets of the same composition, the dual-alloy sintering process yields magnets with a more uniform elemental distribution and superior magnetic properties.

To promote CO₂ redox kinetics on the cathode of hybrid sodium−carbon dioxide (Na−CO₂) batteries, hollow cubic CuS nanoboxes were encapsulated in polypyrrole and polydopamine by in situ polymerization of pyrrole and dopamine monomers, respectively, and coupled with high-temperature heat treatment to obtain nitrogen−carbon encapsulated Cu_xS@NC_PPy and Cu_xS@NC_PDA catalysts. The results show that the encapsulation of nitrogen-doped carbon not only increases the specific surface area and improves the electron affinity but also promotes the synergistic interaction between the CuS-based active species and the defect carbon, thus providing abundant active sites for CO₂ conversion. The electrochemical performances of the carbon-coated modified samples were all improved, especially the hybrid Na−CO₂ battery based on Cu_xS@NC_PPy, which showed a low voltage gap of 0.74 V at 0.1 mA/cm² and a high power density of 3.42 mW/cm².

A three-dimensional (3D) electromagnetic (EM) inversion algorithm based on the nonlinear conjugate gradient (NLCG) method and a two-color plane Gauss−Seidel (GS) multigrid (MG) forward solver is developed to improve inversion efficiency. The results indicate that the computational efficiency of each inversion can be improved by approximately a factor of three by using the proposed MG solver. First, the accuracy of the MG solver is validated through a test on a synthetic model. Next, the numerical performance of the inversion algorithm is evaluated using this model. Finally, the inversion algorithm is applied to a field EM data collected at the Beiya gold polymetallic ore district. A 3D resistivity model is obtained, and the formation process of the metal ore is analyzed.

The leaching mechanism of gallium (Ga) and germanium (Ge) from zinc powder replacement residue (ZPRR) was investigated through ultrasonic-assisted sulfuric acid leaching. Characterization via XRD, SEM, XPS, and FT-IR revealed that ultrasonic treatment promotes the dehydration of H₄SiO₄ colloids, thereby reducing their adsorption capacities for Ga and Ge complexes. Additionally, ultrasound enhances the dissolution of CaS in H₂SO₄, increasing H₂S production, which aids in the reduction of Fe³⁺ and mitigates iron precipitate formation. Process parameters including ultrasonic power (0−450 W), temperature (100−120 °C), and leaching time (30−120 min) were systematically optimized, achieving optimal leaching efficiencies of Ga and Ge at 95.7% and 94.5%, respectively.

The leaching process and kinetic behavior of lepidolite in hydrochloric acid were explored systematically. The influence of leaching conditions on the leaching efficiency of valuable metals in lepidolite was investigated. Under optimized conditions, the leaching efficiencies of Li, K, Rb, Cs and Al are 92.02%, 93.31%, 88.59%, 86.75% and 81.07%, respectively. Kinetics research results show that the leaching process conforms to the shrinking core model that is under the mixed control of chemical reaction and diffusion through the solid product layer. In addition, the contribution of solid product layer diffusion to the leaching gradually expands as the temperature rises, but it is still significantly less than the contribution of chemical reaction. Cost saving in the neutralizing agent and leaching processes makes hydrochloric acid an economical leaching agent for lepidolite. Finally, the Li₂CO₃ product with a purity of 99.89% was synthesized from the hydrochloric acid leachate.

The modified molecular interaction volume model (M-MIVM) was used to calculate the activity values and their deviations from experimental data for Ag−Cu and Ag−Sb binary alloys. Subsequently, theoretical vapor−liquid equilibrium phase diagrams (T−x−y and p−x−y) were plotted via combining M-MIVM and vacuum theory. The vapor−liquid phase equilibrium (VLE) experiments were conducted on the Ag−Cu alloy at 1500−1560 K and 10−15 Pa and Ag−Sb alloys at 950−1350 K and 10 Pa. The results showed that the average relative deviation and average standard deviation of activity were lower than 5% and 0.02, respectively. A comparison of theoretical and experiment results for VLE revealed that the simulated data on the T−x−y diagram were well consistent with experimental values. Therefore, the VLE phase diagrams can serve as a guide in vacuum separation experiments and industrial production for Ag−Cu and Ag−Sb binary alloys.

The electrochemical separation of Mn(II) impurity from molten NaCl−KCl−MgCl₂ was systematically investigated to facilitate the electrolytic production of high-purity magnesium. The reduction of Mn(II) to Mn metal on tungsten electrode was a quasi-reversible process controlled by diffusion. The apparent standard potential and exchange current density of Mn(II)/Mn(0) electrode reaction were determined at temperatures ranging from 973 to 1048 K. Solid Mn metal generated during electrolysis aggregated into irregular clumps and adsorbed some needle-like MgO, imposing a detrimental effect on both the aggregation and the purity of magnesium metal. After electrolysis at −1.5 V in molten NaCl−KCl−MgCl₂−0.62wt.%MnCl₂ for 8 h, the concentration of MnCl₂ impurity decreased to 0.037 wt.%, achieving a removal efficiency of 94.14%. When direct electrolysis was performed in molten NaCl−KCl−MgCl₂−0.62wt.%MnCl₂, the obtained magnesium metal was small blocks with a caviar-like appearance, and the purity was just 98.59%. In contrast, a large globule of magnesium metal was obtained when electrolysis was performed in the purified electrolyte, and its purity was improved to 99.94%. The controlled-potential electrolysis proposed in this work has been verified to be a green and practically effective method to separate the metal ion impurities from molten electrolyte for high purity magnesium extraction.