Additive manufacturing (AM) technology has emerged as a viable solution for manufacturing complex- shaped WC−Co cemented carbide products, thereby expanding their applications in industries such as resource mining, equipment manufacturing, and electronic information. This review provides a comprehensive summary of the progress of AM technology in WC−Co cemented carbides. The fundamental principles and classification of AM techniques are introduced, followed by a categorization and evaluation of the AM techniques for WC−Co cemented carbides. These techniques are classified as either direct AM technology (DAM) or indirect AM technology (IDAM), depending on their inclusion of post-processes like de-binding and sintering. Through an analysis of microstructure features, the most suitable AM route for WC−Co cemented carbide products with controllable microstructure is identified as the indirect AM technology, such as binder jet printing (BJP), which integrates AM with conventional powder metallurgy.

The water-quenched (WQ) 2195 Al−Li alloy was subjected to stretching at different temperatures, from room temperature (RT) to −196 °C (CT), to investigate the effect of cryogenic deformation on the aging precipitation behaviors and mechanical properties. The precipitation kinetics of the T1 phase and the microstructures in peak aging state were investigated through the differential scanning calorimetric (DSC) tests and electron microscopy observation. The results show that −196 ℃ deformation produces a high dislocation density, which promotes the precipitation of the T1 phase and refines its sizes significantly. In addition, the grain boundary precipitates (GBPs) of −196 °C-stretched samples are suppressed considerably due to the high dislocation density in the grain interiors, which increases the ductility. In comparison, the strength remains nearly constant. Thus, it is indicated that cryogenic forming has the potential to provide the shape and property control for the manufacture of critical components of aluminum alloys.

The age-hardening response, mechanical, and corrosion-resistant properties of AA7085 alloys with and without the addition of 0.3 wt.% scandium (Sc) were compared. Using advanced techniques such as aberration-corrected transmission electron microscopy and first-principles calculations, the underlying micromechanisms of Sc microalloying were revealed. Results show that the increase in strength of the AA7085-Sc alloy is mainly attributed to the decreased Al grain size and increased number density of both Al₃Sc@Al₃(Sc,Zr) core−shell nanoparticles and Sc-containing η_p and GP−η_p nanoprecipitates. Strong strain fields and evident electron transfer from Zr to the neighboring matrix Al atoms exist at the Al₃Sc@Al₃(Sc,Zr)/Al interface. The Sc doping in GP−η_p and η_p suppresses the GP−η_p → η_p transformation. Modified corrosion resistance of the AA7085-Sc alloy compared with AA7085 alloy is associated with the fine grain boundary precipitates of η phases and narrow precipitation free zone. The reasons of property changes of AA7085 alloy after Sc microalloying are explored based on the multiscale microstructural characterization.

The evolution of the S' precipitate in Al−Cu−Mg alloy was investigated using transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF−STEM), molecular dynamics (MD) simulations, and other analytical techniques. The precipitation behavior during different aging stages of the supersaturated solid solution formed after rapid cold punching was focused, which induces rapid dissolution of precipitates. The findings reveal that the precipitation sequence is significantly influenced by aging temperature. At higher aging temperatures, which mitigate lattice distortion in the matrix, the precipitation sequence follows the conventional path. Conversely, at lower aging temperatures, where lattice distortion persists, the sequence deviates, suppressing the formation of Guinier−Preston−Bagaryatsky (GPB) zones. MD simulations confirm that the variations in solute atom diffusion rates at different aging temperatures lead to the differences in the S' phase precipitation sequence.

The dissimilar 2B06 and 7B04 Al alloy joints were prepared by refill friction stir spot welding (RFSSW), and the microstructural evolution and corrosion behavior of the joints were investigated. Based on microstructural analysis, the welded joints exhibit distinct microstructural zones, including the stir zone (SZ), thermomechanically affected zone (TMAZ), and heat-affected zone (HAZ). The grain size of each zone is in the order of HAZ > TMAZ > SZ. Notably, the TMAZ and HAZ contain significantly larger secondary-phase particles compared to the SZ, with particle size in the HAZ increasing at higher rotational speeds. Electrochemical tests indicate that corrosion susceptibility follows the sequence of HAZ > TMAZ > SZ > BM, with greater sensitivity observed at increased rotational speeds. Post-corrosion mechanical performance degradation primarily arises from crevice corrosion at joint overlaps, but not from the changes in the microstructure.

The dependence of shrinkage porosities on microstructure characteristics of Mg−12Al alloy was investigated. The distribution, morphology, size, and number density of shrinkage porosities were analyzed under different cooling rates. The relationship between shrinkage porosities and microstructure characteristics was discussed in terms of temperature conditions, feeding channel characteristics, and feeding capacity. Further, the feeding behavior of the residual liquid phase in the solid skeleton was quantified by introducing permeability. Results show a strong correlation between the solid microstructure skeleton and shrinkage porosity characteristics. An increase in permeability corresponds to a declining number density of shrinkage porosities. This study aims to provide a more complete understanding how to reduce shrinkage porosities by controlling microstructure characteristics.

The effects of artificial aging (T6) on the creep resistance with tensile stresses in the range of 50−80 MPa at 175 °C were investigated for an extruded Mg−1.22Al−0.31Ca−0.44Mn (wt.%) alloy. The Guinier-Preston (G.P.) zones primarily precipitate in the sample aged at 200 °C for 1 h (T6-200°C/1h), while the Al₂Ca phases mainly precipitate in the sample aged at 275 °C for 8 h (T6-275°C/8h). The T6-200°C/1h sample exhibits excellent creep resistance, with a steady-state creep rate one order of magnitude lower than that of the T6-275°C/8h sample. The abnormally high stress exponent (~8.2) observed in the T6-200°C/1h sample is associated with the power-law breakdown mechanism. TEM analysis illuminates that the creep mechanism for the T6-200°C/1h sample is cross-slip between basal and prismatic dislocations, while the T6-275°C/8h sample exhibits a mixed mechanism of dislocation cross-slip and climb. Compared with the Al₂Ca phase, the dense G.P. zones effectively impede dislocation climb and glide during the creep process, demonstrating superior creep resistance of the T6-200°C/1h sample.

A new method was proposed for preparing AZ31/1060 composite plates with a corrugated interface, which involved cold-pressing a corrugated surface on the Al plate and then hot-pressing the assembled Mg/Al plate. The results show that cold-pressing produces intense plastic deformation near the corrugated surface of the Al plate, which promotes dynamic recrystallization of the Al substrate near the interface during the subsequent hot-pressing. In addition, the initial corrugation on the surface of the Al plate also changes the local stress state near the interface during hot pressing, which has a large effect on the texture components of the substrates near the corrugated interface. The construction of the corrugated interface can greatly enhance the shear strength by 2−4 times due to the increased contact area and the strong “mechanical gearing” effect. Moreover, the mechanical properties are largely depended on the orientation relationship between corrugated direction and loading direction.

In order to overcome the embrittlement of metastable titanium alloys caused by the precipitation of ω_iso phase during aging, regulation of isothermal ω precipitation was investigated in Ti−15Mo alloy. The results show that the sample is brittle when direct aging (A) is applied at 350 °C for 1 h after solution treatment (ST). If pre-deformation (D) is performed on the ST sample to induce {332} twins and secondary α′′ phase, subsequent aging at 350 °C (STDA350) improves the strength to 931 MPa with a good ductility of about 20% maintained. However, when aging is performed at 400 °C or 450 °C (STDA400/450), the strength can be further improved, but the ductility is dramatically reduced. Atomic-scale characterizations show that the partial collapse of ω phase in the STDA350 sample effectively eliminates aging-induced embrittlement, but complete collapse leads to poor ductility in the STDA400/450 sample.

The effect mechanism of electroshock treatment (EST) on microstructure evolution and mechanical property variations of Ti−8Al−1Mo−1V alloy was investigated. The results show that EST results in the phase transformation from the acicular secondary α_s to β phase. While the EST time is 0.12 s, the acicular martensitic phase (α_M) precipitates. The results of electron backscattered diffraction (EBSD) reveals that the average grain size decreases from 3.95 to 2.53 μm after EST, indicating that the grains are refined, and the significant recrystallization behavior and martensitic transformation occur. The orientation distribution reveals a more uniform distribution of texture, which is caused by the variation of crystal orientation after the phase transformation. The compression fracture behavior of materials indicates that EST significantly enhances the yield strength while reduces the fracture strain. The improvement of yield strength is mainly attributed to the precipitation of martensitic phase. All results indicate that EST is an effective approach for manipulating the microstructure and optimizing the texture distribution of titanium alloys.

Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates. The evolution and mechanisms affecting the interfacial bonding strength in titanium/stainless steel laminated composites were investigated. Results indicate that the hardened layer reduces the interfacial bonding strength from over 261 MPa to less than 204 MPa. During the cold roll-bonding process, the hardened layer fractures, leading to the formation of multi-scale cracks that are difficult for the stainless steel to fill. This not only hinders the development of an interlocking interface but also leads to the presence of numerous microcracks and hardened blocks along the nearly straight interface, consequently weakening the interfacial bonding strength. In metals with high work hardening rates, the conventional approach of enhancing interface interlocking and improving interfacial bonding strength by using a surface-hardened layer becomes less effective.

The microstructural evolution of Cu−19Ni−6Cr−7Mn alloy during aging treatment was investigated. After aging for 120 min at 500 °C, the alloy exhibited excellent mechanical properties, including a tensile strength of 978 MPa and an elastic modulus of 145.8 GPa. After aging for 240 min at 500 °C, the elastic modulus of the alloy reached 149.5 GPa, which was among the highest values reported for Cu alloys. It was worth mentioning that the tensile strength increased rapidly from 740 to 934 MPa after aging for 5 min at 500 °C, which was close to the maximum tensile strength (978 MPa). Analysis of the underlying strengthening mechanisms and phase transformation behavior revealed that the Cu−19Ni−6Cr−7Mn alloy underwent spinodal decomposition and DO₂₂ ordering during the first 5 min of aging at 500 °C, and L1₂ ordered phases and bcc-Cr precipitates appeared. Therefore, the enhanced mechanical properties of the Cu−19Ni−6Cr−7Mn alloy can be attributed to the stress field generated by spinodal decomposition and the presence of nanoscale ordered phase and Cr precipitates.

Machine learning-assisted methods for rapid and accurate prediction of temperature field, mushy zone, and grain size were proposed for the heating−cooling combined mold (HCCM) horizontal continuous casting of C70250 alloy plates. First, finite element simulations of casting processes were carried out with various parameters to build a dataset. Subsequently, different machine learning algorithms were employed to achieve high precision in predicting temperature fields, mushy zone locations, mushy zone inclination angle, and billet grain size. Finally, the process parameters were quickly optimized using a strategy consisting of random generation, prediction, and screening, allowing the mushy zone to be controlled to the desired target. The optimized parameters are 1234 °C for heating mold temperature, 47 mm/min for casting speed, and 10 L/min for cooling water flow rate. The optimized mushy zone is located in the middle of the second heat insulation section and has an inclination angle of roughly 7°.

The composition−property relationship of 18 quaternary high entropy diborides (HEBs) consisting of boron and IVB, VB and VIB transition metals (TM) was investigated using first-principles calculations. A valence electron concentration−relative electronegativity (VEC−REN) composite descriptor was developed to effectively predict the mechanical properties of HEBs. The results demonstrate that with a fixed VEC, the rise of the REN makes HEBs harder but more brittle when the electronegativity of doped TM atoms is lower than that of boron atoms. However, HEBs become softer and more ductile as REN increases if the doped TM atoms have higher electronegativity than boron atoms. The VEC−REN composite descriptor can accurately classify and predict the mechanical properties of HEBs with different components, which provides important theoretical guidance for the rapid design and development of novel high-entropy ceramic materials.

Low-density superalloys often exhibit low yield strength in the intermediate temperature range (300−650 °C). To enhance yield performance in this range, the CALPHAD method was used to design a new Co-based superalloy. The Co−30Ni−10Al−3V−6Ti−2Ta alloy, designed based on γʹ phase dissolution temperature and phase fraction, was synthesized via arc melting and heat treatment. Phase transition temperatures, microstructure evolution, and high-temperature mechanical properties were characterized by differential scanning calorimetry, scanning electron microscopy, dual-beam TEM, and compression tests. Results show that the alloy has low density (8.15 g/cm³) and high γʹ dissolution temperature (1234 °C), along with unique yield strength retention from room temperature to 650 °C. The yield strength anomaly (YSA) is attributed to high stacking fault energy and activation of the Kear−Wilsdorf locking mechanism, contributing to superior high-temperature stability of the alloy. The yield strength of this alloy outperforms other low-density Co-based superalloys in the temperature range of 23−650 °C.

Some active metal oxides (Al₂O₃, TiO₂, and Cr₂O₃) were selected as dopants to the Al₂O₃-based ceramic shells for investment casting of K417G superalloy. The effects of dopant types and contents (0, 2, 5, and 8 wt.%) on the wettability and interfacial reaction between the alloy and shell were investigated by a sessile-drop experiment. The results show that increasing the Al₂O₃ doping contents (0−8 wt.%) reduces the porosity (21.74%−10.08%) and roughness (3.22−1.34 μm) of the shell surface. The increase in Cr₂O₃ dopant content (2−8 wt.%) further exacerbates the interfacial reaction, leading to an increase in the thickness of the reaction layer (2.6−3.1 μm) and a decrease in the wetting angle (93.9°−91.0°). The addition of Al₂O₃ and TiO₂ dopants leads to the formation of Al₂TiO₅ composite oxides in the reaction products, which effectively inhibits the interfacial reaction. The increase in TiO₂ dopant contents (0−8 wt.%) further promotes the formation of Al₂TiO₅, which decreases the thickness of the interfacial reaction layer (3.9−1.2 μm) and increases the wetting angle (95.0°−103.8°). The introduced dopants enhance the packing density of the shell surface, while simultaneously suppress the diffusion of active metal elements from the alloy matrix to the interface.

The Sn−2Al filler metal was utilized to bond W90 tungsten heavy alloys by the ultrasonic-assisted coating technology in atmospheric environment at 250 °C. The effects of ultrasonic power and ultrasonic time on microstructure and interfacial strength of Sn−2Al/W90 interface were investigated. The ultrasound improved the wettability of Sn−2Al filler metal on W90 surface. As the ultrasonic power increased and ultrasonic time increased, the size of Al phase in seam decreased. The maximum value of Sn−2Al/W90 interfacial strength reached 30.1 MPa. Based on the acoustic pressure simulation and bubble dynamics, the intensity of cavitation effect was proportional to ultrasonic power. The generated high temperature and high pressure by cavitation effect reached 83799.6 K and 1.26×10¹⁴ Pa, respectively.

The flotation separation of argentite from sphalerite using ammonium dibutyl dithiophosphate (ADD) was studied. Molecular simulation (MS) calculation shows that ADD is chemisorbed on argentite and sphalerite surface in the form of S—P bond. The ADD adsorption on argentite and sphalerite surface in Ag⁺ system was revealed by ICP, Zeta potential and XPS analyses. It is shown that the dissolved Ag⁺ from argentite surface can be absorbed on sphalerite surface in the form of silver hydroxide, and AgOH hydrophilic colloid prevents the adsorption of ADD on sphalerite surface. The ADD adsorption on argentite and sphalerite surface in the pulp containing silver and zinc ions was revealed by adsorption capacity and surface wettability analyses. It is shown that the combined Zn(OH)₂ and AgOH hydrophilic colloid leads to greater ADD adsorption capacity on argentite surface and stronger surface hydrophobicity than sphalerite. Flotation tests demonstrate that ADD enables efficient separation of argentite from sphalerite in the pulp containing silver and zinc ions.

A series of leaching and electrochemical experiments were conducted to elucidate the critical role of hydrogen sulfide (H₂S) in copper-driven reduction of chalcopyrite. Results demonstrate that in the absence of H₂S, metallic copper converts chalcopyrite into bornite (Cu₅FeS₄). However, the introduction of H₂S promotes the formation of chalcocite (Cu₂S) by altering the oxidation pathway of copper. Electrochemical analysis demonstrates that the presence of H₂S significantly reduces the corrosion potential of copper from 0.251 to −0.223 V (vs SHE), reaching the threshold necessary for the formation of Cu₂S. Nevertheless, excessive H₂S triggers sulfate reduction via the reaction of 8Cu+H₂SO₄+3H₂S=4Cu₂S+4H₂O (ΔG=−519.429 kJ/mol at 50 °C), leading to inefficient copper utilization.

The differences in the competitive reactions of hydrogarnet and quicklime when reacting with titanium- containing and silicon-containing minerals during the Bayer digestion process were investigated. Thermodynamic analysis, artificial mineral experiments, and an evaluation of the digestion effect of natural diasporic bauxite were conducted. The results indicate that hydrogarnet shows a preferential reaction with anatase, and this preference becomes more pronounced as the silicon saturation coefficient increases. In contrast, quicklime participates in non-selective reactions with both anatase and desilication products (DSP). The preference of hydrogarnet for anatase significantly enhances the utilization efficiency of CaO in the high-temperature Bayer digestion process.

To synergistically recover alumina and alkali from red mud (RM), the structural stability and conversion mechanism of hydroandradite (HA) from hydrogarnet (HG) were investigated via the First-principles, XRF, XRD, PSD and SEM methods, and a novel hydrothermal process based on the conversion principle was finally proposed. The crystal structure simulation shows that the HA with varied silicon saturation coefficients is more stable than HG, and the HA with a high iron substitution coefficient is more difficult to be converted from HG. The (110) plane of Fe₂O₃ is easier to combine with HG to form HA, and the binding energy is 81.93 kJ/mol. The effects of raw material ratio, solution concentration and hydrothermal parameters on the conversion from HG to HA were revealed, and the optimal conditions for the alumina recovery were obtained. The recovery efficiencies of alumina and Na₂O from the RM are 63.06% and 97.34%, respectively, and the Na₂O content in the treated RM is only 0.13%.

The molten CaCl₂−CaMoO₄ system was investigated, and the electrodeposition of protective Mo coatings on Ni plates was demonstrated. The results confirm the high solubility of solid CaMoO₄ and the electrochemical reactivity of MoO₄^2– ions in molten CaCl₂. The eutectic temperature and composition of the system are identified as 1021 K and 4.74 wt.% CaMoO₄, respectively. Under constant-current electrolysis conditions of −10 mA/cm² at 1123 K, uniform and dense Mo coatings are obtained on Ni plates with up to 90.31% efficiency. Increasing the current density raises the overpotential, leading to refined grains and decreased roughness. The Mo-coated Ni plate exhibits a significant improvement in hardness and corrosion resistance. Microhardness increases from HV 46.00 to HV 215.10 after coating, and the corrosion rate in a 20 wt.% NaCl solution at room temperature decreases to 0.1% that of the bare plate. These findings enhance our understanding of the molten CaCl₂–CaMoO₄ system and emphasize the potential of innovative Mo coating technologies.