The binder jetting additive manufacturing (BJAM) process involves multiple parameters such as layer thickness, reference voltage, powder spreading speed, drying speed, and roller speed etc. Traditional experimental parameter optimization faces severe challenges. Recent generative AI (Gen AI) advancements offer trans-formative potential for manufacturing. This study proposes a novel stacking NeuroSVK model integrated with a Large Language Model (LLM) to optimize printing parameters and simultaneously predict the relative density and dimensional variation of the printed Ti-6Al-4 V green bodies. A printing dataset of 43 experimental sets was evaluated using K-fold cross-validation for comprehensive model training and validation. Predictive accuracy was assessed via Mean Squared Error (MSE) and the coefficient of determination (RPorter et al. (2023)2). The LLM was fine-tuned with 100 prompts to help evaluate the reasonableness of model-optimized parameters and to develop a question-answering agent. Results show the model's recommendations are very close to the experi-mental optimum with R2 of 0.94, and the agent evaluates the reasonableness of the recommended parameters. Importantly, the density distribution of green bodies printed using the model's parameters is more stable than with experimentally optimized parameters. Finally, the TC4 engine piston printed using the model-optimized parameters was sintered at 1400 degrees C for 2 h, and a relative density >= 97% was reached. The microstructure consisted of alpha-phase with an average grain size of 28.09 +/- 14.23 mu m and beta-phase at grain boundaries, with a microhardness of 362 HV, tensile strength of 1015 +/- 23 MPa, elongation of 10.2 +/- 0.6%, carbon content of 0.14 wt%, oxygen content of 0.28 wt%, and dimensional shrinkage of 15.75%, 14.55%, and 18.34% in the X, Y, and Z directions, respectively.

This paper reports the first systematic study on the optimization of key process parameters for binder jet additive manufacturing of M2 high-speed steel and their influence on the properties of green bodies and sintered parts. Through systematical optimization of the curing time, ultrasonic vibration time, screen size, layer thickness, and reference voltage, the relative density, dimensional accuracy, and compressive strength of the green bodies were significantly improved. Based on the powder packing theory, the coarse-to-fine volume ratio of bimodal powder was optimized to 8: 1, thereby achieving a high packing density of 4.378 g/cm3. During the sintering process, the effects of temperature and holding time on microstructure evolution and mechanical properties were systematically investigated. The results demonstrated that after sintering at 1290 degrees C for 60 min, the samples achieved a relative density exceeding 95.7%, with compressive strength reaching 2762 MPa, the compressive strain measuring 26%, the hardness registering 628 HV, and the surface roughness (Rz) as low as 0.067 mm. Microstructural analysis revealed that the sintered microstructure consisted primarily of an alpha-Fe matrix, irregular MC carbides, and fishbone-like or network-structured M6C carbides. Increasing sintering temperature and time induces three key changes: First, grain-boundary M6C carbides coarsen and become inhomogeneous; second, grains undergo significant growth; third, secondary phases (e.g., retained austenite) persist, whose stability is governed by liquid-phase behavior and carbide reprecipitation. This study provides critical theoretical and technological insights for the high-precision and high-performance fabrication of M2 high-speed steel via binder jetting additive manufacturing.

In this study, the Sb- and Bi-alloyed Sn-Cu systems were investigated. By integrating sublattice modeling, Rietveld refinement, EBSD technique, and nanoindentation tests, the regulatory mechanisms of alloying on the crystal structure, texture evolution, and mechanical behavior of intermetallic compounds (IMCs) were systematically explored. Phase evolution at various temperatures was calculated based on the CALPHAD method. In the Sn-Cu system, the η'-Cu6Sn5, η-Cu6Sn5, and Cu3Sn phases exhibit distinct crystal structures and atomic site occupancy characteristics. At elevated temperatures, the vacancies in η-Cu6Sn5 provide essential pathways for atomic diffusion. The addition of Sb and Bi increased the liquid phase volume fraction during the sintering process, effectively enhancing the microstructural uniformity. The Sb- and Bi-alloyed intermetallic compounds were fabricated via powder metallurgy (PM). Subsequently, the influence of alloying on crystallographic orientation was characterized and analyzed through Rietveld refinement and EBSD techniques. In the Sn-39.1Cu alloy, the η'-Cu6Sn5 grains exhibit a preferred orientation predominantly along the (010) and (001) directions. Following the addition of Sb, the crystallographic orientation of η'-Cu6Sn5 tends to become randomized, which significantly mitigates/weakens the micro-anisotropy of the material. The η-Cu6Sn5 phase exhibits orientation-dependent variations at different locations. Nanoindentation characterization reveals disparities in the mechanical properties of the alloy; specifically, the pop-in phenomenon observed in η'-Cu6Sn5 is attributed to dislocation nucleation and pile-up. Furthermore, Bi-alloying reduces the steady-state creep rate, effectively enhancing the creep resistance of the material, which contributes positively to the long-term service reliability of solder joints.

Binder jetting 3D printing (BJ3DP) offers significant advantages in fabricating complex metal components, yet the relative density and dimensional accuracy of green parts depend heavily on process parameters. This study investigates the effects of layer thickness, white ink concentration, roller traverse speed, and roller rotation speed on the relative density and three-dimensional deviations of GH2132 superalloy green parts. Orthogonal experiments and range analysis yield a preliminary optimum (50 µm, 50%, 45 p/ms, 60 p/ms), achieving 56.19% density. Five machine learning models are compared, with ANN selected as the surrogate (average R 2 = 0.9164). SHAP interpretation on the independent test set reveals nonlinear segmented characteristics of white ink concentration, identifying its optimal range as 30%–50%. Feature contributions to density rank as layer thickness > white ink concentration > roller rotation speed > roller traverse speed. Bayesian optimization with normalized Euclidean distance mapping yields the recommended window (50 µm, 40%, 40 p/ms, 70 p/ms), predicting 57.89% density. Validation experiments show that the measured relative density is 58.3%, with X‑, Y‑, and Z‑axis deviations of 0.36, 0.24, and 0.06 mm, respectively, all within 2% relative to the nominal dimensions, confirming the effectiveness and engineering applicability of the proposed optimization framework.

Zinc alloys are increasingly recognized in medical applications for their biocompatibility and degradation rates, yet their mechanical limitations and complex strengthening processes impede broader application. In this study, Zn-1Mg alloy with moderate mechanical strength and biodegradability as a potential bone implant was firstly prepared using semisolid powder molding. The effects of forming temperatures (370, 390, 400 degrees C) and holding time (20 min, 30 min) on the microstructures, mechanical and corrosion properties of Zn-1Mg were studied. The results show that the optimal microstructure, featuring a fine alpha-Zn matrix and a spiral eutectic of Mg2Zn11-MgZn2, was achieved at 390 degrees C-20 min with 25 % of compaction ratio. At this preparation condition, the prepared alloy has a relative density of 93.6 %, microhardness of 98.2HV, elastic modulus of 85.7 GPa, compressive strength of 249.5 MPa, elongation of 70 %, and the electrochemical corrosion rate of 0.12 mm/year. Higher forming temperature enhances the atomic diffusion between Zn powder and Mg powder, therefore, the liquid eutectic Zn-Mg alloys forms during semi-solid isothermal. The increasing liquid flows and fills in the pores during forming, and it solidifies with spiral eutectic of Mg2Zn11-MgZn2 because of the fast cooling. Initially, the appropriate liquid enhances densification and properties. However, extended holding times and higher compaction ratios decrease these properties due to excess liquid and porosity. The fractures of the powder and eutectic structures make microstructures finer. This study validates that semisolid powder molding is a promising technique to produce medical biodegradable zinc alloys.

This study presents the results of printing parameters optimization of Binder Jetting 3D printed 2024Al alloy assisted by machine learning (ML). The effects of layer thickness and resolution on the printed 2024Al green parts including relative density, dimensional change and compressive strength were analyzed. The green parts printed with the optimized printing parameters were sintered, and their sintering behavior was analyzed. The results show the effect of layer thickness on the relative density and compressive strength of the green body is greater than that of resolution. However, the influence of resolution on the dimensional accuracy is higher than that of layer thickness. Based on the experimental results, the optimized printing parameters can be determined to be a layer thickness of 0.06 mm, a resolution of 1000*800, and a binder saturation range of 30%-70%, the relative density is 58.4%. For the few shot dataset, ANN is the optimized model to predict the printing process with the highest value of R2 above 0.92, and the calculated results agree well with the experimental results. The relative density of green part sintered in N2 atmosphere increases from 58.4% to 90%, and the optimized sintering temperature for 2024Al is 600 degrees C. The microstructure of sintered part is composed of alpha-Al, Al2Cu and a few of AlN, and the microhardness above 100 HV. AlN is more likely to form on the surface of the advancing liquid during pore filling, which is helpful for the densification.

The Mannich base corrosion inhibitor could efficiently inhibit the uniform corrosion of 13Cr stainless steel in the conditions of high-temperature acidizing and fracturing in deep carbonate reservoirs, but it only has a limited ability to inhibit the pitting corrosion. To further enhance the pitting corrosion inhibition effect, thiourea was compounded with Mannich base, and the inhibition effect and release mechanism were systematically studied. The inhibition ability of the mixed inhibitor was evaluated by weight loss, electrochemical experiments, and 3D microscopy. The adsorption tendency of the thiourea-compounded Mannich base inhibitor on the surface of 13Cr stainless steel was studied by density functional theory analysis and molecular dynamics simulation. X-ray photoelectron spectroscopy (XPS) was used to detect and analyze the adsorption and distribution of the inhibitors. When the addition amount of thiourea was 4 g/L, the corrosion inhibition efficiency of 1% Mannich base inhibitor reached the highest. In hydrochloric acid solutions with concentrations of 10%, 15%, and 20%, the inhibition efficiencies were 99.96%, 99.65%, and 99.28% respectively, and the pitting depths were the shallowest. Results of electrochemical studies indicated that the Mannich base corrosion inhibitor can simultaneously inhibit the cathode and anode reactions, and it was a mixed-type corrosion inhibitor mainly controlling the anode process. Based on the theoretical analysis of molecular frontier orbitals and the outcomes of molecular dynamics simulations, the Mannich base inhibitor molecules were spontaneously adsorbed on the surface of 13Cr stainless steel, with a tendency towards parallel adsorption.

Currently, Selective Laser Melted (SLM) titanium alloys can meet the demands of personalized medical devices, but their poor surface roughness results in suboptimal surface biocompatibility. A low cost, high-efficiency 3D printing method, binder jetting additive manufacturing (BJAM), effectively address this issue. Furthermore, the application of bioactive coating on the BJAM-ed titanium alloy implants can enhance their surface bioinertness. This study synthesized Mn-MOFs via a solvothermal method, and then investigated the effects of synthesis temperature on the morphology, structure, and cyto-toxicity of Mn-BTC. Finally, the Mn-BTC with the best biocompatibility were coated on the BJAM-ed TC4 implant. The results indicate that Mn3+ was gradually reduced to Mn2+ by the thermodynamic driving forces, prompting a morphological transition of Mn-BTC from asymmetric polyhedrons to uniform spheres. This valence-morphology synergy significantly reduces the cytotoxicity of Mn-BTC synthesized at 170 degrees C. Subsequently, the 170 degrees C-synthesized Mn-BTC was coated on the BJAM-TC4 titanium alloy implants via micro-arc oxidation (MAO) to fabricate a Mn-BTC/MAO-TC4 coating. This coating not only effectively improves the RGR (increase by 12.1 %) compared to BJAM-TC4 but also significantly promotes BMSC adhesion performance. This study unveils the structure-activity relationship between temperature and morphology in Mn-BTC, providing a novel strategy for the surface functionalization of BJAM titanium alloy implants.

Objective Titanium matrix composites have attracted considerable attention because of their high modulus of elasticity, high specific strength, high wear resistance, and excellent high- temperature durability. Most studies on titanium matrix composites (TMCs) focus primarily on the in- situ formed TiC reinforced composites. However, few studies have focused on the direct addition of TiC-reinforced- reinforced titanium matrices. The manners in which the size, morphology, and distribution of TiC evolve during the SLM process and how they affect the microstructure and mechanical properties remain unclear. In this study, TiC/TC4 composites with directly added nanoscale TiC particles are successfully prepared by selective laser melting (SLM), and the microstructure evolution under different volume energy densities is investigated. Further, the TiC evolution during SLM and its influence on the microstructure and microhardness are analyzed. Thus, the findings of this study can provide the support for SLM preparation of titanium composites. Methods Herein, nanoscale TiC (diameter of 50-150 nm) and TC4 are selected as the reinforced phase and matrix, respectively. The composite powder with TiC uniformly embedded on the surface of the TC4 powder is obtained by low- energy ball milling. Subsequently, the TiC/TC4 composites are prepared via SLM with different volume energy densities (29-97 J/mm3). 3 ). The forming quality and microstructures at different volume energy densities are observed using optical microscopy (OM) and scanning electron microscopy (SEM) equipped energy disperse spectroscope (EDS). The grain size and crystal orientation are investigated using electron backscattering diffractometer (EBSD), and the phase compositions are measured using X-ray- ray diffraction (XRD). Finally, the microhardness is measured using a digital microhardness tester. Results and Discussions The optimized volume energy densities for the SLM formed TiC/TC4 composites are in the range of 50 - 70 J/mm3, 3 , with a relative density of 99.7% (Fig. 3). Owing to the enrichment of TiC in the melt pool boundary zone, the microstructure of the composites exhibits a special double- sized grain distribution in the cross section (Fig. 6). Owing to the rapid cooling characteristics of the SLM process, TiC cannot be sufficiently dissolved. Therefore, the SEM and EBSD results reveal three types of reinforcement: undissolved TiC, eutectic TiC, and precipitated TiC. Undissolved TiC is distributed primarily at the boundaries of coarse beta equiaxed grains, eutectic TiC is distributed primarily in the boundaries of irregular eutectic beta grains, and precipitated TiC is distributed primarily in the grains. With an increase in volume energy density, the chain- like eutectic TiC gradually transforms to rod- like eutectic TiC (Figs. 7 and 8), the size of precipitated TiC inside the grain gradually increases, and the sizes of longitudinal and transverse alpha'-Ti- Ti gradually increase. Conclusions The optimal volume energy density for the formation of TiC/TC4 composites by SLM is 50 - 70 /mm3, 3 , and the relative density is 99.7% within this parameter range. TiC is enriched in the melt- pool boundary region under a strong temperature gradient and Marangoni convection. The microstructure of the composite has a special double- size grain distribution in the cross section, consisting of primary beta equiaxed grains and irregular eutectic regions growing on the periphery. In the longitudinal section, the molten pool is a fish scale, and some chain structures exist in the molten pool that grow from the direction of heat flow to the horizontal direction. With an increase in volume energy density, the size of primary beta equiaxed grains decreases, outer- ring irregular eutectic region expands, and morphology of fish scales becomes sharp. The microhardness initially decreases and then increases, essentially reaching 385-392 HV in the optimal molding process window. TiC in the composites is composed primarily of undissolved TiC (distributed near the primary beta grain boundaries), eutectic TiC (distributed in the eutectic beta grain boundaries in a chain or rod- like network), and precipitated TiC (distributed in the grain in a granular manner). With an increase in volume energy density, the difference in TiC size and quantity inside and outside the molten pool increases, chain distribution of eutectic TiC changes to rod, and the size of TiC in the grains increases. Further, no obvious orientation relationship between eutectic TiC and beta- Ti is observed; however, a distinct orientation relationship between eutectic and in- grain TiC and alpha'-Ti- Ti exists: {11-20} alpha'-Ti parallel to{110}TiC.- Ti parallel to{110}TiC.

Objective Selective laser melting (SLM) can be used to prepare functionally gradient materials (FGMs) for local customization of performance. In this study, CuSn10/AlSi10Mg functional gradient materials were prepared by SLM, and the effect of the material composition ratio on the microstructure of the CuSn10/AlSi10Mg transition layer was investigated. The phase and quantity of the transition layer were calculated using CALPHAD, the microstructural evolution of the interface region of the gradient materials was discussed based on electron backscattering diffraction (EBSD) results, and the formation mechanism of cracks in the interface region was revealed. The results show that the microstructure of the CuSn10/AlSi10Mg transition layer consists of a matrix of Al4Cu9 and Al2Cu with columnar and fine equiaxed grains. In the transition layer zone (from the copper alloy side to the aluminum alloy side), with an increase in the AlSi10Mg content, the matrix content does not change significantly, whereas the content of Al/Cu intermetallic compounds changes sharply. The Al4Cu9 phase first precipitates and its content gradually decreases, whereas the Al2Cu phase precipitates later and its content gradually increases, and a large amount of Al/Cu intermetallic compounds are generated around the cracks. The main reason for the formation of severe cracks in the transition zone is that the directly generated Al4Cu9 phase is prone to large volume changes (4.4 degrees o ), leading to stress concentration and initial microcracks. The large volume change (4.3 degrees o ) caused by the transformation of the Al2Cu phase and Cu enriched in the matrix into the Al4Cu9 phase (indirectly generated) further exacerbates the stress concentration and ultimately leads to macrocracking. Avoiding the direct and indirect generation of Al4Cu9 is the primary means of solving the problem of cracking. The microhardness of the transition layer is higher than that of the matrix on both sides. The highest hardness is observed at the crack (804 HV), similar to that of Al4Cu9. Methods In this study, CuSn10/AlSi10Mg gradient functional materials are prepared by SLM through two gradient paths (19 and 16 layers of different compositional gradients are designed for samples 1 and 2, respectively). The microstructures of the different transition regions are observed by optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). To reveal the microstructural evolution, the phase compositions of the transition regions are measured using X- ray diffraction (XRD) and EBSD. Finally, the microhardness is measured using a microhardness tester to understand the changes in mechanical properties. Results and Discussions Sample 1 (19- layer transition composition) prepared using SLM forms more cracks, generates transverse cracks, and causes macroscopic cracking throughout the sample. Sample 2 (16- layer transition composition) forms slight cracks, and the transverse cracks disappears. Although both transition compositions have cracks, the 19- layer transition is significantly more severe than the 16- layer transition. More importantly, nearly all the cracks are generated in the Al- rich transition region (Fig. 2). During the printing process, the distribution of Al along the deposition direction gradually increases from zero at the beginning to a uniform distribution at the end, which is consistent with the spot scanning results. However, both Cu and Sn are uniformly distributed throughout the transition region, which further confirms that the CuSn10 alloy is continuously remelted and is then diffused to the upper layer during the printing process, resulting in the enrichment of Cu in the region of the Al alloy (Fig. 4). In the transition region, the phases mainly consist of the matrix phase alpha-Cu/alpha-Al and Al/Cu intermetallic compounds, and the intermetallic compounds are mainly Al4Cu9 and Al2Cu. From the Cu alloy side to the Al alloy side, the content of the matrix does not change significantly with the addition of the Al alloy. In addition, Al4Cu9 first precipitates and then gradually decreases, and it is dominant at 40 degrees o AlSi10Mg. With a continuous increase in the Al alloy content, the Al2Cu phase precipitates later and gradually increases, exceeding the Al4Cu9 phase at 50 degrees o AlSi10Mg content (Figs. 5-7). Conclusions The microstructure of the SLMed CuSn10/AlSi10Mg gradient material is composed of columnar and fine equiaxed grains that grow in the direction of the center of the molten pool, and the equiaxed grains close to the boundary of the molten pool have a random grain orientation. In the transition region, the phases mainly consist of alpha-Cu/alpha-Al matrix and Al/Cu intermetallic compounds, and the intermetallic compounds are mainly Al4Cu9 and Al2Cu. From the Cu10Sn side to the AlSi10Mg side, with the addition of the Al alloy, the content of the matrix does not change significantly, but Al4Cu9 first precipitates and gradually decreases, and it dominates at 40 degrees o AlSi10Mg. With a continuous increase in the aluminum alloy, the Al2Cu phase precipitates later and gradually increases, exceeding the content of the Al4Cu9 phase at 50 degrees o AlSi10Mg. A large amount of the Al4Cu9 phase is generated around the microcracks in the transition region. However, a large amount of the Al2Cu phase is generated around the macrocracks, and nearly all cracks mainly occur in the Al- rich transition region. The volume change of the generated Al4Cu9 is the highest (4.4 degrees o ), and the reaction between Al2Cu and the Cu matrix forming the Al4Cu9 phase exhibits the second- highest volume change (4.3 degrees o ), whereas the volume change forming the Al2Cu phase is only 0.3 degrees o. The Al4Cu9 phase nucleates in both Al- and Cu- rich solid solutions, whereas the Al2Cu phase can only nucleate in the Al- rich region. Therefore, the reason for crack formation is that the direct generation of the Al4Cu9 phase in the transition region is prone to forming a stress concentration that generates the initial microcracking. The indirectly formed Al4Cu9 (the reaction between Al2Cu and excess Cu in the matrix) causes a large volume change and further aggravates the stress concentration, resulting in severe macrocracks. Avoiding the generation of the Al4Cu9 phase (including direct and indirect formations) is the primary means of solving the cracking problems. The microhardness of the transition layer region is affected by the intermetallic compound content. From the Cu alloy side to the Al alloy side, the microhardness first increases and then decreases, and it is higher in the transition region than that of the substrate. This trend is consistent with the number of intermetallic compounds. The highest microhardness (804 HV) is observed at the cracks, which is very close to that of This further verifies that enriched intermetallic are the main reason for crack formation.

Mg alloys with advantages of biocompatibility and biodegradability are considered as a new type of medical material with great potential. Compared with casting and additive manufacturing, Semi-solid powder forming (SPF) is a promising new technique to prepare medical Mg alloys due to the characteristics of fine microstructures, a short process cycle and good comprehensive properties. In this study, the micromechanism of Mg-6Zn mixed powder materials under a semi-solid isothermal and deformation station was analyzed and discussed based on the results of SEM, EDS, XRD, synchrotron radiation X-ray computed tomography (SRXCT) and kinetic analysis. The results show all the Zn powders melt and Mg powder dissolves into the liquid Zn to form a Zn-Mg liquid wrapping around the Mg powders the semi-solid isothermal state. The powder particle boundary blurred and transgranular liquation cracking (TLC) occurs under the loading force, making the powders being broken into fragments which spheroidize and coarsen afterward. Simultaneously, the dynamic model of Mg-6Zn mixed powders was deduced and established, which agrees well with the experimental results and can predict the actual liquid fraction during SPF. The pores reconstructed by SRXCT has a low connectivity, near-spherical morphology and flat surface, combined with encapsulated microstructure with finer grains and fewer secondary phases, which are beneficial to slow down the degradation rate. Finally, the micromechanism of SPF was concluded as atomic diffusion, liquid flowing and filling, transgranular liquation cracking (TLC) of particles as well as coarsening and spheroidizing of its fragments, which provides theoretical guidance for optimizing the forming process.

Soaking time and loading rate are the two important process parameters for semi-solid powder forming, which are next only to powder temperature. However, there have been few investigations on the influence of soaking time and loading rate on the semi-solid compression of porous material, which is an effective method for studying the deformation characteristics of semi-solid materials and is widely used to optimize the semi-solid forming processes. Therefore, the microstructures, grain size and shape factor, liquid fraction, relative densities and stress–strain curves of Al-4Cu-Mg alloy with a porosity of 30

Magnesium alloys are used as bone implants because of their good biocompatibility and degradability. However, due to the rapid and uneven degradation, its clinical application is limited. To improve the corrosion resistance of medical magnesium alloys, a novel technique of semisolid powder molding was used to prepare Mg-6Zn alloy, and then microarc oxidation (MAO) was firstly applied to modify the surface. In this study, the effects of different current densities (4, 6, 8 A/dm2) and microarc oxidation time (8, 14, 20 min) on the phase composition, thickness, density, microstructure, roughness, and corrosion resistance of MAO film were systematically studied, and then the optimized parameters were obtained. Finally, the optimized coating's biocompatibility (cytotoxicity, cell adhesion, hemolysis, osteogenic differentiation) was evaluated. The results show that the MAO film mainly comprises α-Mg, MgO, and Mg2SiO4. The film’s roughness, microhardness, and thickness increase with the current density and oxidation time. The lowest electrochemical corrosion rate of the coating is (2.3 ± 0.5 × 10–4 mm/year under the parameter of 6 A/dm2-20 min, which decreases by about 3 orders of magnitude compared with naked Mg-6Zn (0.32 ± 0.06 mm/year). The optimized microarc oxidation parameter is 6 A/dm2-20 min, with a thickness of 18 ± 1.45 μm, and microhardness of 339.6 ± 9.09 HV (increases by 165.3

Semi-solid powder rolling (SSPR) is widely used to produce alloy strips with fine grains and excellent performances in the automotive, aerospace and shipbuilding industries. During SSPR, powder temperature, as a very important parameter, greatly affects strips’ microstructures and mechanical properties, which have been investigated by many researchers, but its effect on the forming process and mechanism has rarely been studied. Therefore, based on online experimental detection and transient simulation, the microstructures, strip temperatures, relative densities and rolling forces at different conditions were, respectively, measured, calculated, compared and analyzed in order to study the deformation process and mechanism during SSPR. The result shows that with the increase in powder temperature, the strip temperature and relative density increase, while the rolling force decreases. The grains of the strips are refined after SSPR, and fine and dense microstructures are obtained at 600 °C, which is the optimum powder temperature. In the main deformation sections (II and III), when the contact normal force exists and reaches a maximum, the relative density and rolling force increase rapidly. At these sections, the strips rolled at 600 °C are mainly in a porous solid state, and powder crushing dominates the strip deformation. Therefore, SSPR at 600 °C and below can be considered porous or powder hot rolling, integrating powder crushing, solidification, deformation, densification and grain coarsening. Moreover, as the simulated values are basically consistent with experimental values, the thermomechanical coupling model based on the Fourier equation and its parameters are confirmed to be reasonable.

Semisolid powder molding was used to prepare the medical Mg-6Zn alloy; in order to further improve its degradation adaptability, 0.5 and 1 wt % Mn were added. Then, the effect of the forming temperature (540, 560, 580, and 600 °C) on the in vitro degradation behavior of the prepared Mg-6Zn-xMn (x = 0.5, 1 wt %) was analyzed, and the optimized alloy was obtained. Finally, the biocompatibility and in vivo degradation performance of the optimized and Mn-free alloys were evaluated. Importantly, single-photon emission tomographic imaging (SPECT/CT) was first applied to monitor the in vivo degradation process. The results show that the corrosion mechanism of the Mn-free alloy is microgalvanic corrosion control with corrosive pitting. After adding Mn, the in vitro degradation rate decreases by half (0.17 ± 0.01 mm/year) as the forming temperature increases to 600 °C, and Mg-6Zn-1Mn prepared at 600 °C is the optimized alloy. Mn addition improves the corrosion product film protection and discontinuous secondary phases, and thus, the corrosion mechanism is changed to corrosive pitting control. Additionally, semisolid powder molding is an easy method to prepare alloys with low average pore interconnectivity (<10%), which is helpful for slowing down the degradation rate. The Mn-containing alloy has better biocompatibility, with a cytotoxicity of grade 0-1, due to its lower degradation rate. The in vivo corrosion rate of the Mn-free alloy is 0.19 mm/year after 28 days of implantation, which was precisely detected by SPECT/CT in real-time. The long-term in vivo degradation adaptability of Mn-free and Mn-containing alloys was not correctly presented, which may be due to the unreasonable bone defect model causing implant displacement. However, both of these alloys cause no obvious inflammation and show good healing. In summary, semisolid powder molding is a potentially promising technique to prepare medical Mg alloys, and nuclear imaging is an effective in vivo degradation evaluation method.

Under the background of multiple challenges such as regional energy, environment, climate and economy, ASEAN "10+5" should explore new paths of energy cooperation. High-quality energy cooperation has its profound history, theory and realistic logic, which is reflected in the starting point, process and result of cooperation. Examining the present situation, predicament and foundation of bilateral and multilateral energy cooperation in ASEAN "10+5" region, it is found that although regional energy cooperation has made great progress, it faces difficulties such as fragmented cooperation, overlapping mechanism, poor environment, unstable relationship, concentrated content and structural imbalance. China should base itself on solving practical problems and cooperating for high-quality development, and explore a series of improvement and innovation strategies on the concept, relationship, goal, mode, environment, content, scope, structure, subject and benefit of regional energy cooperation, so as to enhance the stability,rationality, effectiveness, sustainability and toughness of energy cooperation.

数字化、智能化时代的到来,使得智能制造课组成为目前高校材料成型及控制工程专业建设和革新的方向之一.针对专业建设中存在的一些问题,该文主要探讨了新工科背景下材料成型及控制工程专业智能制造课组建设的相关思路,在分析了材料成型及控制工程专业智能制造课组建设必要性的基础上,提出了建设的策略,包括确立新的教学目标、创新专业课程教育体系、强化师资力量建设、搭建特色实践平台、建立课程考核评价及改进机制.

With advantages of powder metallurgy and semi-solid forming, Semi-solid powder rolling (SPR) as a novel technology was proposed and has been widely used to produce high-performance strips currently. As SPR is an extremely complex process and influenced by many factors, consequently it is necessary to be researched by the simulation method to study the forming process and various influence laws, in order to save experimental time and cost. Therefore, in this work, a two-dimensional model was built based on the Shima-porous yield criterion by using Marc software, considering the effect of temperature and relative-density on thermal conductivity, heat capacity, elastic modulus and Poisson's ratio. The semi-solid rolling process of Al–Cu–Mg alloy powder was simulated by the model, and the relative-density and rolling-force of strips were calculated and proven by experiments, which are basically consistent with the measured values. Based on this model, the influence of main parameters on SPR strips was analyzed. The results show that the rolling temperature of strips increases with the roller temperature increasing, and changes little with the variation of the compression ratio, rotational velocity and friction factor. The rolling-force reduces with the increase in roller temperature and the decrease in compression ratio, rotational velocity and friction factor. The relative-density rises as the four parameters increase. According to the results, it is suggested that a moderate roller temperature, a relatively large compression ratio and a small rotational velocity are recommended during the actual rolling, which provides a theoretical guidance for semi-solid powder forming experiments.

Semi-solid powder forming (SPF) has been widely used to prepare metal matrix composites, during which powder breakage plays an important role in grain refinement and densification process. However, it is not easy to directly observe because of the complicated SPF process, resulting in few investigations. Therefore, based on semisolid compression of AA2024 porous materials, powder breakage behavior and mechanism were studied by introducing the continuity, capillary force, and Newtonian fluid and Roscoe–Einstein model in this work. The results indicate that when the continuity CSS≈1, the powders are not crushed, the liquid solidified as short-rod shapes distributing within a powder is regarded as small holes, and its influence is ignored. When CSS = 0.384–0.608, the powders break up along grain boundaries partially occupied by liquid, with their solid-bonding being torn open, resulting in transgranular ruptures. Its breakage resistance is the combined force acted by the solid-bonding and liquid. When CSS < 0.384, the solid grains are wrapped by liquid with few deformation resistances, regarded as a Newtonian fluid. The breakage resistance of semi-solid powders was calculated by the deduced mathematical equation, and it further confirmed the above results. The breakage coefficient representing the broken degree was calculated and then proved to be consistent with experimental results.

Transarterial radioembolization (TARE) with 90Y-labeled glass and resin microspheres is one of the primary treatment strategies for advanced-stage primary and metastatic hepatocellular carcinoma (HCC). However, difficulties of real-time monitoring post administration and embolic hypoxia influence treatment prognosis. In this study, we developed a new biodegradable polymer microsphere that can simultaneously load 177Lu and MgO nanoparticle, and evaluated the TARE therapeutic efficacy and biosafety of 177Lu-PDA-CS-MgO microspheres for HCC treatment.Chitosan microspheres were synthesized through emulsification crosslink reaction and then conducted surface modification with polydopamine (PDA). The 177Lu and nano MgO were conjugated to microspheres using active chemical groups of PDA. The characteristics of radionuclide loading efficiency, biodegradability, blood compatibility, and anti-tumor effectwere evaluated both in vitro and in vivo. SPECT/CT imaging was performed to monitor bio-distribution and bio-stability of 177Lu-PDA-CS-MgO after TARE treatment. The survival duration of each rat was monitored. HE analysis, TUNEL analysis, immunohistochemical analysis, and western blot analysis were conducted to explore the anti-tumor effect and mechanism of composited microspheres. Body weight, liver function, blood routine examination were monitored at different time points to evaluate the bio-safety of microspheres.The composite 177Lu-PDA-CS-MgO microsphere indicated satisfactory degradability, biocompatibility, radionuclide loading efficiency and radiochemical stability in vitro. Cellular evaluation showed that 177Lu-PDA-CS-MgO had significant anti-tumor effect and blocked tumor cell cycles in S phase. Surgical TARE treatment with 177Lu-PDA-CS-MgO significantly prolonged the medial survival time from 49 d to 105 d, and effectively inhibited primary tumor growth and small metastases spreading. Moreover, these microspheres indicated ideal in vivo stability and allowed real-time SPECT/CT monitoring for up to 8 weeks. Immunostaining and immunoblotting results also confirmed that 177Lu-PDA-CS-MgO had potential in suppressing tumor invasion and angiogenesis, and improved embolic hypoxia in HCC tissues. Further evaluations of body weight, blood test, and pathological analysis indicated good biosafety of 177Lu-PDA-CS-MgO microspheres in vivo.Our study demonstrated that 177Lu-PDA-CS-MgO microsphere hold great potential as interventional brachytherapy candidate for HCC therapy. Polymer composite microspheres loading 177Lu radionuclide and MgO nanoparticles for interventional radioembolization therapy and real-time SPECT imaging of hepatic cancer.