Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusi...Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed slightly.The dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)increased.With the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical<2111>-<1123>rare-earth(RE)textures.The alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening contributions.These results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.展开更多
This paper focuses on the space charge and breakdown characteristics of polypropylene(PP)-based insulation interface in extrusion moulded joint(EMJ)for high-voltage direct current(HVDC)submarine cables.The double-laye...This paper focuses on the space charge and breakdown characteristics of polypropylene(PP)-based insulation interface in extrusion moulded joint(EMJ)for high-voltage direct current(HVDC)submarine cables.The double-layered flat samples and cylindrical samples are prepared to imitate the interface in the PP-insulated EMJ.The DC conductivity,space charge,and breakdown strength are tested.The results demonstrate that in the EMJ manufacturing process,the lower wielding temperature leads to microdefects at the insulation interface.As shallow traps,the microdefects exacerbate hetero charge accumulation,thereby intensifying the electric field distortion and increasing the conductivity.Meanwhile,the interfacial microdefects lead to a reduction in the insulation breakdown strength.At 90°C,the normal and tangential breakdown strengths decrease by a maximum of 20.6%and 54.5%,respectively.Notably,the space charges and microdefects lead to a rapid decline in the breakdown strength after hetero polarity pre-stressing.Especially for the tangential breakdown strength,the maximum decrease rate reaches 22.9%.Therefore,the interfacial microdefects caused by the drop in the welding temperature are the primary factors leading to a serious decrease in the electrical properties of EMJ insulation,making the EMJ insulation weaker than PP cable insulation.展开更多
The Mg-Y-Zn magnesium alloy system is known for the presence of Long-Period Stacking Ordered(LPSO)phases that improves strength and ductility with minimal amounts of alloying elements.Even better improvements are asso...The Mg-Y-Zn magnesium alloy system is known for the presence of Long-Period Stacking Ordered(LPSO)phases that improves strength and ductility with minimal amounts of alloying elements.Even better improvements are associated with the specific microstructure known as the Mille-Feuille(MF)structure that can occur in this alloy as well after proper heat treatment.This study systematically compares the traditional ingot metallurgy method with the Bridgman method(slow cooling),coupled with diverse heat treatments and extrusion process.Microscopic analyses reveal variations in the presence of LPSO phases,MF structure,and especially grain size,leading to divergent mechanical and corrosion properties.The Bridgman approach surprisingly stands out,ensuring superior mechanical properties due to kink and texture strengthening.展开更多
Traditional manufacturing processes for lightweight curved profiles are often associated with lengthy procedures,high costs,low efficiency,and high energy consumption.In order to solve this problem,a new staggered ext...Traditional manufacturing processes for lightweight curved profiles are often associated with lengthy procedures,high costs,low efficiency,and high energy consumption.In order to solve this problem,a new staggered extrusion(SE)process was used to form the curved profile of AZ31 magnesium alloy in this paper.The study investigates the mapping relationship between the curvature,microstructure,and mechanical properties of the formed profiles by using different eccentricities of the die.Scanning electron microscopy(SEM)and electron backscatter diffraction techniques are employed to examine the effects of different eccentricity values(e)on grain morphology,recrystallization mechanisms,texture,and Schmid factors of the products.The results demonstrate that the staggered extrusion method promotes the deep refinement of grain size in the extruded products,with an average grain size of only 15%of the original billet,reaching 12.28μm.The tensile strength and elongation of the curved profiles after extrusion under the eccentricity value of 10 mm,20 mm and 30 mm are significantly higher than those of the billet,with the tensile strength is increased to 250,270,235 MPa,and the engineering strain elongation increased to 10.5%,12.1%,15.9%.This indicates that staggered extrusion enables curvature control of the profiles while improving their strength.展开更多
Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with...Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with three infill patterns(rectilinear, grid, and honeycomb) were prepared using bauxite slurry and slurry extrusionbased additive manufacturing technology, and the effects of infill patterns on the properties were evaluated. The hierarchical pores inside the wall are composed of the macropores formed by infills and the micropores among bauxite particles. Different infill patterns result in changes in distribution and shape of pores, thereby affecting the properties of the shell moulds. The honeycomb pattern has more comprehensive advantages compared to the other two infill patterns. The samples prepared with the honeycomb pattern exhibit the highest bending strength(11.62 MPa) and porosity(41.6%), as well as good heat-transfer ability, with an average shrinkage rate within 2.0%. This work provides an attractive feasibility for fabricating shell moulds with hierarchical porous walls.展开更多
This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on t...This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on the extrusion die cavity as well as their effects on the mechanical properties were emphatically investigated.Results showed that dynamic recrystallization refined the grain size and improved the microstructure homogeneity in the three extrusion specimens,but did not produce too large microstructure differences.By comparison,significant texture differences developed owing to the various extrusion die cavities,which here were mainly reflected in the strong or weak texture components for the c-axes//TD and the c-axes//ND.Such texture differences started from the deformation texture instead of the recrystallization texture whose roles only consisted in dispersing the texture component and reducing the texture intensity.The results from the finite element analysis and the visco-plastic self-consistent model indicated that,in order to accommodate the different strain components induced by the extrusion die cavities,slip systems or tension twinning were activated differently,and this was the critical reason causing the above texture differences.One modified Hall-Petch relationship was adopted to analyze the conjoint effects of grain refinement and texture variation on the yield stress.Additionally,the quantitative results about deformation mechanism activation fractions demonstrated that the texture variations influenced the competition relationships between the twinning induced deformation and the slip dominant deformation,and the former generally produced the lower yield stress and the increasing stage of strain hardening rate,while the latter produced the higher yield stress and the continuous decline of strain hardening rate.展开更多
Obtaining high strength in low-RE-alloyed Mg alloys(RE<6 wt%)remains a huge challenge so far.In this work,we fabricated a novel high-strength and low-RE-alloyed Mg-3Yb-0.6Zn-0.4Zr(wt%)alloy using the conventional e...Obtaining high strength in low-RE-alloyed Mg alloys(RE<6 wt%)remains a huge challenge so far.In this work,we fabricated a novel high-strength and low-RE-alloyed Mg-3Yb-0.6Zn-0.4Zr(wt%)alloy using the conventional extrusion at low temperature,which breaks through the stereotypical"fewer RE,lower strength"wisdom.The microstructure of the alloy and mechanical properties were examined with op-tical microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and Instron testing machine.This alloy exhibits a high tensile yield strength of 410 MPa and a favorable elongation of 7.8%,outperforming the majority of traditional high-strength Mg-Gd-Y(-Zn)-Zr extrusion alloys with high RE additions,at least 12 wt%.The high yield strength of the alloy is closely associated with the synergistic effect of submicron recrystallized grains and highly-textural hot-worked grains containing numerous dynamic precipitates and residual dislocations,rather than the widely-considered age-hardening in those heavy RE containing Mg alloys.This work provides an important reference for the development of high-performance extruded Mg alloys with low RE solutes.展开更多
The utilization of lunar regolith for construction on the lunar surface presents a critical challenge in-situ resource utilization.This study proposes a lunar regolith manufacturing method that uses a high-performance...The utilization of lunar regolith for construction on the lunar surface presents a critical challenge in-situ resource utilization.This study proposes a lunar regolith manufacturing method that uses a high-performance resin binder characterized by a high regolith content and strong forming capabilities.A combined resin material with both thermosetting and photosetting properties was developed and mixed with lunar regolith to create a slurry.This slurry can be directly molded or additively extruded into green bodies with specific structures.These green bodies can self-cure under the high temperatures and ultraviolet radiation experienced during the lunar day,reducing energy consumption and fulfilling the requirements of lunar construction.The material-forming processes and effects of various additive types and concentrations,regolith mass ratios,and processing parameters on the properties of the slurry and the formed specimens were thoroughly investigated.The mechanical performance and microstructure of the fabricated samples were analyzed.The lunar regolith mass ratio reached 90 wt%(approximately 79 vol%),with the highest compressive strengths exceeding 60 MPa for cast specimens and 30 MPa for printed samples.This technology shows significant potential for enabling in-situ lunar regolith-based construction in future lunar missions.展开更多
The microstructure and mechanical properties of Mg−4.5Al−2.5Zn−0.3Mn−0.2Ca(wt.%,designated as AZ42)alloys in extruded(at extrusion ratios of 28,20 and 11.5)and peak-aged states were investigated,by using optical micro...The microstructure and mechanical properties of Mg−4.5Al−2.5Zn−0.3Mn−0.2Ca(wt.%,designated as AZ42)alloys in extruded(at extrusion ratios of 28,20 and 11.5)and peak-aged states were investigated,by using optical microscopy,scanning electron microscopy,energy dispersive spectrometry and electron backscatter diffraction.The results show that extrusion produces a typical basal fiber texture and streamlines of second phases.All samples exhibit the lowest Schmid factor of basal slip(SFb)and the superior tensile yield strength(TYS)along extrusion direction(ED).The sample with extrusion ratio of 20 exhibits the largest average grain size,but the smallest SFb which compensates for the disadvantage of grain coarsening and maintains the strength.After being peak-aged at 175℃for 48 h,the sample with the extrusion ratio of 20 shows the optimal TYS along all the directions,compared to the other samples.This hopes to provide useful information for optimizing the deformation parameters of the AZ42 alloys.展开更多
To tackle the common issue of green defects in material extrusion(MEX)additive manufacturing(AM)cemented carbides,warm isostatic pressing(WIP)was introduced to eliminate defects of MEX WC-9Co cemented carbide greens,t...To tackle the common issue of green defects in material extrusion(MEX)additive manufacturing(AM)cemented carbides,warm isostatic pressing(WIP)was introduced to eliminate defects of MEX WC-9Co cemented carbide greens,thereby improving both microstructure uniformity and mechanical properties of sintered bodies.The results indicate that WIP reduces defects in MEX greens,thus decreasing the dimensions and numbers of defects,modifying shapes of pores within sintered bodies,while preserving surface quality and shape characteristics.Compared with WC-9Co prepared via MEX followed by debinding and sintering(DS),the hardness of WC-9Co prepared using MEX-WIP-DS does not change significantly,ranging HV_(30)1494-1508,the transverse rupture strength increases by up to 49.3%,reaching 2998-3514 MPa,and the fracture toughness remains high,ranging 14.8-17.0 MPa·m^(1/2).The mechanical properties surpass comparable cemented carbides fabricated through other AM methods and are comparable to those produced by powder metallurgy.The integration of green WIP into MEX-DS broadens the MEX processing window,and improves the overall mechanical properties of MEX AM WC-Co cemented carbides.展开更多
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 te...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{123}<111>and Cu{112}<111>evolve into S{123}<634>,and the Bs{011}<211>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.展开更多
Mg-1.2Y-1.2Ni(at.%)alloy was extruded at 400℃with an extrusion ratio of 16:1 and different rates from 1 to 6 mm/s.The effect of extrusion rate on microstructure and mechanical properties of the Mg-1.2Y-1.2Ni alloy wa...Mg-1.2Y-1.2Ni(at.%)alloy was extruded at 400℃with an extrusion ratio of 16:1 and different rates from 1 to 6 mm/s.The effect of extrusion rate on microstructure and mechanical properties of the Mg-1.2Y-1.2Ni alloy was systematically investigated.With the increase of extrusion rate,the average recrystallized grain size of Mg-1.2Y-1.2Ni alloy and mean particle diameter of Mg2Ni phase were increased,while the density of geometrically necessary dislocation and the intensity of the basal texture were decreased.When extrusion rate increases from 1 to 6 mm/s,the tensile yield strength(TYS)of asextruded Mg-1.2Y-1.2Ni alloy decreases from 501 to 281 MPa,while the elongation to failure increases from 1.5%to 6.2%.The Mg-1.2Y-1.2Ni alloy extruded at 3 mm/s obtained TYS of 421 MPa,the ultimate tensile strength(UTS)of 440 MPa and elongation to failure of 2.6%,respectively,exhibiting comprehensive mechanical properties with relatively good plasticity and ultrahigh strength.The ultrahigh TYS of 501 and 421 MPa was mainly due to the strengthening from ultrafine recrystallized grains,high volume fraction long period stacking ordered(LPSO)phases and high density dislocations.展开更多
Based on thermodynamic calculations and continuous rheological extrusion(CRE)technology,Al-Ti-V-B master alloys were designed and prepared.The morphology and the distribution of the refined phases in the master alloys...Based on thermodynamic calculations and continuous rheological extrusion(CRE)technology,Al-Ti-V-B master alloys were designed and prepared.The morphology and the distribution of the refined phases in the master alloys were analyzed by XRD,SEM,and TEM.The effects of master alloy addition and holding time on the microstructure and mechanical properties of A356 alloy were investigated.Under the optimum refiner addition of 0.3wt.%and the holding time of 20 min,the average grain size of the refined A356 alloy is 151.8±9.11μm,89.62%lower than that of original A356 alloy.The tensile strength and elongation of as-cast A356refined alloy are 196.11 MPa and 5.75%,respectively.After T6 treatment,the tensile strength and elongation of A356 refined alloy are 290.1 MPa and 3.09%,respectively.The fracture morphology is characterized by a predominance of along-crystal fracture with a small amount of through-crystal fracture,attributed to the refined grains.Finer grains promote crack path deflection and localized plastic deformation,enhancing energy dissipation and reducing the tendency for brittle fracture.This study provides a novel approach to improving the mechanical properties of A356 alloy through grain refinement using CRE Al-Ti-V-B master alloy.展开更多
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 m...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{1012}tensile twins during the tensile deformation,resulting in a reduction in plasticity.展开更多
The effects of trace Ag on the tensile strength and creep resistance of Mg-7.5Gd-1.5Y-0.4Zr(wt.%)extrusion bars were investigated at temperatures of 175-275℃,via tensile tests and creep tests,electron back-scatter di...The effects of trace Ag on the tensile strength and creep resistance of Mg-7.5Gd-1.5Y-0.4Zr(wt.%)extrusion bars were investigated at temperatures of 175-275℃,via tensile tests and creep tests,electron back-scatter diffraction,and transmission electron microscopy.Adding trace Ag improves the tensile strength and creep resistance of Mg-Gd-Y-Zr alloys at elevated temperatures.During the creep process,precipitate-free zones(PFZs)are formed near grain boundaries and perpendicular to the loading direction,while chain-likeβ′-Mg7RE precipitates are distributed in a special direction([1010])in grain interior.After adding Ag element,the creep resistance of the Mg-Gd-Y-Zr-Ag is improved due to the suppression of dislocation movement by the synergistic effect of narrower PFZs,finerβ′-Mg7RE precipitates in the grain interior and more stable β-Mg_(5)RE phase located on the grain boundaries.展开更多
The Mg−Al composite rods of aluminum core-reinforced magnesium alloy were prepared by the extrusion−shear(ES)process,and the microstructure,deformation mechanism,and mechanical properties of the Mg−Al composite rods w...The Mg−Al composite rods of aluminum core-reinforced magnesium alloy were prepared by the extrusion−shear(ES)process,and the microstructure,deformation mechanism,and mechanical properties of the Mg−Al composite rods were investigated at different extrusion temperatures and shear stresses.The experimental results show that the proportion of dynamic recrystallization(DRX)and texture for Al and Mg alloys are controlled by the combination of temperature and shear stress.The texture type of the Al alloys exhibits slight variations at different temperatures.With the increase of temperature,the DRX behavior of Mg alloy shifts from discontinuous DRX(DDRX),continuous DRX(CDRX),and twin-induced DRX(TDRX)dominant to CDRX,the dislocation density in Mg alloy grains decreases significantly,and the average value of Schmid factor(SF)of the basalslip system increases.In particular,partial grains exhibit a distinct dominant slip system at 390℃.The hardness and thickness of the bonding layer,as well as the yield strength and elongation of the Mg alloy,reach their maximum at 360℃as a result of the intricate influence of the combined temperature and shear stress.展开更多
In this study,AZ91D(Mg-9Al-Zn)alloys reinforced with 2 vol%TC4(Ti-6Al-4V)particles fabricated by semi-solid stir casting were extruded at different ratios,resulting in observed grain refinement effects.The research fi...In this study,AZ91D(Mg-9Al-Zn)alloys reinforced with 2 vol%TC4(Ti-6Al-4V)particles fabricated by semi-solid stir casting were extruded at different ratios,resulting in observed grain refinement effects.The research findings demonstrate that both TC4 andβ-Mg_(17)Al_(12) phases contribute to promoting dynamic recrystallization(DRX)nucleation.With increasing extrusion ratio,theβ-phase(Mg_(17)Al_(12))gradually fractures into smaller particles,leading to progressive grain refinement.Furthermore,the transition from〈01-10〉fiber texture to non-basal texture in theα-Mg matrix after hot extrusion is attributed to improved DRX behavior and activation of non-basal slip.As the extrusion ratio increases,the tensile strength and elongation(EL)of TC4_(p)/AZ91D composite improve significantly,reaching optimum comprehensive mechanical properties at an extrusion of 40:1 with a yield strength(YS)of 257 MPa,an ultimate tensile strength(UTS)of 357 MPa,and an EL of 9.7%.This remarkable strengthening effect is primarily attributed toβ-phase reinforcement,grain refinement strengthening,and strain hardening.展开更多
How to reduce peanut allergies has always been a main food safety concern.Plant polyphenol complex peanut sensitizing protein was proposed as a new desensitization strategy.Gallic acid(GA),as a natural plant polypheno...How to reduce peanut allergies has always been a main food safety concern.Plant polyphenol complex peanut sensitizing protein was proposed as a new desensitization strategy.Gallic acid(GA),as a natural plant polyphenol,has anti-inflammatory and immunomodulatory effects.Therefore,the aim of this study was to investigate the effect of GA on peanut protein(PP)sensitization under high moisture extrusion conditions.The contents of free sulfhydryl groups and disulfide bonds in the PP-GA complex were determined,and the structure of the complex was characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)and Fourier transform infrared spectroscopy.The results showed that with increasing GA content,the number of free sulfhydryl groups increased while the number of disulfide bonds decreased.The secondary structure of PP-GA showed that the random coils andβ-turns were transformed toα-helices andβ-sheets.A BALB/c mouse model was also established,wherein Al(OH)3 was used as an adjuvant when the complex was administered via intraperitoneal injection,and the mice showed mild allergic symptoms and a decreased immune organ index.In addition,the serum levels of specific antibodies(immunoglobulin E(IgE),immunoglobulin G1(IgG1),and immunoglobulin G2a(IgG2a)),cytokines(interleukin-5(IL-5),interleukin 13(IL-13),and interferon gamma(IFN-γ))and histamine were reduced.In summary,this study proved that GA can relieve the sensitization of PP induced by high moisture extrusion.展开更多
Silicone material extrusion(MEX)is widely used for processing liquids and pastes.Owing to the uneven linewidth and elastic extrusion deformation caused by material accumulation,products may exhibit geometric errors an...Silicone material extrusion(MEX)is widely used for processing liquids and pastes.Owing to the uneven linewidth and elastic extrusion deformation caused by material accumulation,products may exhibit geometric errors and performance defects,leading to a decline in product quality and affecting its service life.This study proposes a process parameter optimization method that considers the mechanical properties of printed specimens and production costs.To improve the quality of silicone printing samples and reduce production costs,three machine learning models,kernel extreme learning machine(KELM),support vector regression(SVR),and random forest(RF),were developed to predict these three factors.Training data were obtained through a complete factorial experiment.A new dataset is obtained using the Euclidean distance method,which assigns the elimination factor.It is trained with Bayesian optimization algorithms for parameter optimization,the new dataset is input into the improved double Gaussian extreme learning machine,and finally obtains the improved KELM model.The results showed improved prediction accuracy over SVR and RF.Furthermore,a multi-objective optimization framework was proposed by combining genetic algorithm technology with the improved KELM model.The effectiveness and reasonableness of the model algorithm were verified by comparing the optimized results with the experimental results.展开更多
Variable material screw-based material extrusion(S-MEX)3D printing technology provides a novel approach for fabricating composites with continuous material gradients.Nevertheless,achieving precise alignment between th...Variable material screw-based material extrusion(S-MEX)3D printing technology provides a novel approach for fabricating composites with continuous material gradients.Nevertheless,achieving precise alignment between the process parameters and material compositions is challenging because of fluctuations in the melt rheological state caused by material variations.In this study,an invertible extrusion prediction model for 0-40 wt% short carbon fiber reinforced polyether-ether-ketone(SCF/PEEK)in the S-MEX process was established using an invertible neural network(INN)that demonstrated the capabilities of forward flow rate prediction and inverse process optimization with accuracies of 0.852 and 0.877,respectively.Moreover,a strategy for adjusting the screw speeds using process parameters obtained from the INN was developed to maintain a consistent flow rate during the variable material printing process.Benefiting from uniform flow,the linewidth accuracy was improved by 77%,and the surface roughness was reduced by 51%.Adjusting the process parameters by using an INN offers significant potential for flow rate control and the enhancement of the overall performance of variable material 3D printing.展开更多
基金supported by the National Science and Technology Major Project,China(No.2019-VI-0004-0118)the National Natural Science Foundation of China(No.51771152)the National Key R&D Program of China(No.2018YFB1106800)。
文摘Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed slightly.The dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)increased.With the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical<2111>-<1123>rare-earth(RE)textures.The alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening contributions.These results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.
基金National Natural Science Foundation of China under the Grant 52477151 and 52077148Key Science and Technology Programme of Yunnan Province,China under Grant 202202AC080002.
文摘This paper focuses on the space charge and breakdown characteristics of polypropylene(PP)-based insulation interface in extrusion moulded joint(EMJ)for high-voltage direct current(HVDC)submarine cables.The double-layered flat samples and cylindrical samples are prepared to imitate the interface in the PP-insulated EMJ.The DC conductivity,space charge,and breakdown strength are tested.The results demonstrate that in the EMJ manufacturing process,the lower wielding temperature leads to microdefects at the insulation interface.As shallow traps,the microdefects exacerbate hetero charge accumulation,thereby intensifying the electric field distortion and increasing the conductivity.Meanwhile,the interfacial microdefects lead to a reduction in the insulation breakdown strength.At 90°C,the normal and tangential breakdown strengths decrease by a maximum of 20.6%and 54.5%,respectively.Notably,the space charges and microdefects lead to a rapid decline in the breakdown strength after hetero polarity pre-stressing.Especially for the tangential breakdown strength,the maximum decrease rate reaches 22.9%.Therefore,the interfacial microdefects caused by the drop in the welding temperature are the primary factors leading to a serious decrease in the electrical properties of EMJ insulation,making the EMJ insulation weaker than PP cable insulation.
基金supported by Japan Society for the Promotion of Science(KAKENHI Grant-in-Aid for Scientific Research,18H05475,18H05476 and JP20H00312)MRC International Collaborative Research Grant+4 种基金The authors would like to thank the Czech Science Foundation(Project No.22-22248S)specific university research(A1_FCHT_2024_007)for financial supportsupported by the Ministry of Education,Youth,and Sports of the Czech Republic.Project No.CZ.02.01.01/00/22_008/0004591co-funded by the European UnionCzechNanoLab project LM2023051 funded by MEYS CR is gratefully acknowledged for the financial support of the measurements/sample fabrication at LNSM Research Infrastructure。
文摘The Mg-Y-Zn magnesium alloy system is known for the presence of Long-Period Stacking Ordered(LPSO)phases that improves strength and ductility with minimal amounts of alloying elements.Even better improvements are associated with the specific microstructure known as the Mille-Feuille(MF)structure that can occur in this alloy as well after proper heat treatment.This study systematically compares the traditional ingot metallurgy method with the Bridgman method(slow cooling),coupled with diverse heat treatments and extrusion process.Microscopic analyses reveal variations in the presence of LPSO phases,MF structure,and especially grain size,leading to divergent mechanical and corrosion properties.The Bridgman approach surprisingly stands out,ensuring superior mechanical properties due to kink and texture strengthening.
基金Project(JQ2022E004)supported by the Natural Science Foundation of Heilongjiang Province,China。
文摘Traditional manufacturing processes for lightweight curved profiles are often associated with lengthy procedures,high costs,low efficiency,and high energy consumption.In order to solve this problem,a new staggered extrusion(SE)process was used to form the curved profile of AZ31 magnesium alloy in this paper.The study investigates the mapping relationship between the curvature,microstructure,and mechanical properties of the formed profiles by using different eccentricities of the die.Scanning electron microscopy(SEM)and electron backscatter diffraction techniques are employed to examine the effects of different eccentricity values(e)on grain morphology,recrystallization mechanisms,texture,and Schmid factors of the products.The results demonstrate that the staggered extrusion method promotes the deep refinement of grain size in the extruded products,with an average grain size of only 15%of the original billet,reaching 12.28μm.The tensile strength and elongation of the curved profiles after extrusion under the eccentricity value of 10 mm,20 mm and 30 mm are significantly higher than those of the billet,with the tensile strength is increased to 250,270,235 MPa,and the engineering strain elongation increased to 10.5%,12.1%,15.9%.This indicates that staggered extrusion enables curvature control of the profiles while improving their strength.
基金financially supported by the National Natural Science Foundation of China (No. 52062029)the Key Science and Technology Project of Gansu Province (No. 18YF1GA064)the Natural Science Foundation of Gansu Provence (No. 25JRRA094)。
文摘Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with three infill patterns(rectilinear, grid, and honeycomb) were prepared using bauxite slurry and slurry extrusionbased additive manufacturing technology, and the effects of infill patterns on the properties were evaluated. The hierarchical pores inside the wall are composed of the macropores formed by infills and the micropores among bauxite particles. Different infill patterns result in changes in distribution and shape of pores, thereby affecting the properties of the shell moulds. The honeycomb pattern has more comprehensive advantages compared to the other two infill patterns. The samples prepared with the honeycomb pattern exhibit the highest bending strength(11.62 MPa) and porosity(41.6%), as well as good heat-transfer ability, with an average shrinkage rate within 2.0%. This work provides an attractive feasibility for fabricating shell moulds with hierarchical porous walls.
基金supported by National Natural Science Foundation of China(Grant No.52205344,51925401)Postdoctoral Research Foundation of China(Grant No.2023M732398)+1 种基金National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(Grant No.WDZC2023-1)Key Research and Development Program of Shandong Province(Grant No.2023CXPT066).
文摘This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on the extrusion die cavity as well as their effects on the mechanical properties were emphatically investigated.Results showed that dynamic recrystallization refined the grain size and improved the microstructure homogeneity in the three extrusion specimens,but did not produce too large microstructure differences.By comparison,significant texture differences developed owing to the various extrusion die cavities,which here were mainly reflected in the strong or weak texture components for the c-axes//TD and the c-axes//ND.Such texture differences started from the deformation texture instead of the recrystallization texture whose roles only consisted in dispersing the texture component and reducing the texture intensity.The results from the finite element analysis and the visco-plastic self-consistent model indicated that,in order to accommodate the different strain components induced by the extrusion die cavities,slip systems or tension twinning were activated differently,and this was the critical reason causing the above texture differences.One modified Hall-Petch relationship was adopted to analyze the conjoint effects of grain refinement and texture variation on the yield stress.Additionally,the quantitative results about deformation mechanism activation fractions demonstrated that the texture variations influenced the competition relationships between the twinning induced deformation and the slip dominant deformation,and the former generally produced the lower yield stress and the increasing stage of strain hardening rate,while the latter produced the higher yield stress and the continuous decline of strain hardening rate.
基金supported by National Natural Science Foundation of China(52201111,52201137,52275389)Taiyuan University of Science and Technology Scientific Research Initial Funding(20232102)+1 种基金Reward funds for excellent doctor of work in coming to Shanxi(No.20242068)Special fund for Scienceand Technology Innovation Teamsof ShanxiProvince.
文摘Obtaining high strength in low-RE-alloyed Mg alloys(RE<6 wt%)remains a huge challenge so far.In this work,we fabricated a novel high-strength and low-RE-alloyed Mg-3Yb-0.6Zn-0.4Zr(wt%)alloy using the conventional extrusion at low temperature,which breaks through the stereotypical"fewer RE,lower strength"wisdom.The microstructure of the alloy and mechanical properties were examined with op-tical microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and Instron testing machine.This alloy exhibits a high tensile yield strength of 410 MPa and a favorable elongation of 7.8%,outperforming the majority of traditional high-strength Mg-Gd-Y(-Zn)-Zr extrusion alloys with high RE additions,at least 12 wt%.The high yield strength of the alloy is closely associated with the synergistic effect of submicron recrystallized grains and highly-textural hot-worked grains containing numerous dynamic precipitates and residual dislocations,rather than the widely-considered age-hardening in those heavy RE containing Mg alloys.This work provides an important reference for the development of high-performance extruded Mg alloys with low RE solutes.
基金supported by International Partnership Program of the Chinese Academy of Sciences(Grant No.310GJH2024010GC)National Natural Science Foundation of China(Grant No.52005479)the China Building Materials Federation(Grant No.2023JBGS0401)。
文摘The utilization of lunar regolith for construction on the lunar surface presents a critical challenge in-situ resource utilization.This study proposes a lunar regolith manufacturing method that uses a high-performance resin binder characterized by a high regolith content and strong forming capabilities.A combined resin material with both thermosetting and photosetting properties was developed and mixed with lunar regolith to create a slurry.This slurry can be directly molded or additively extruded into green bodies with specific structures.These green bodies can self-cure under the high temperatures and ultraviolet radiation experienced during the lunar day,reducing energy consumption and fulfilling the requirements of lunar construction.The material-forming processes and effects of various additive types and concentrations,regolith mass ratios,and processing parameters on the properties of the slurry and the formed specimens were thoroughly investigated.The mechanical performance and microstructure of the fabricated samples were analyzed.The lunar regolith mass ratio reached 90 wt%(approximately 79 vol%),with the highest compressive strengths exceeding 60 MPa for cast specimens and 30 MPa for printed samples.This technology shows significant potential for enabling in-situ lunar regolith-based construction in future lunar missions.
基金supported by the National Natural Science Foundation of China(No.51904036)the Hunan Provincial Key Research and Development Program,China(No.2023GK2049)+2 种基金Changsha Municipal Natural Science Foundation,China(Nos.kq2402016,kq2402014)the Postgraduate Scientific Research Innovation Project of Hunan Province,China(No.CX20240772)the Sichuan Science and Technology Program,China(No.2024NSFSC0151)。
文摘The microstructure and mechanical properties of Mg−4.5Al−2.5Zn−0.3Mn−0.2Ca(wt.%,designated as AZ42)alloys in extruded(at extrusion ratios of 28,20 and 11.5)and peak-aged states were investigated,by using optical microscopy,scanning electron microscopy,energy dispersive spectrometry and electron backscatter diffraction.The results show that extrusion produces a typical basal fiber texture and streamlines of second phases.All samples exhibit the lowest Schmid factor of basal slip(SFb)and the superior tensile yield strength(TYS)along extrusion direction(ED).The sample with extrusion ratio of 20 exhibits the largest average grain size,but the smallest SFb which compensates for the disadvantage of grain coarsening and maintains the strength.After being peak-aged at 175℃for 48 h,the sample with the extrusion ratio of 20 shows the optimal TYS along all the directions,compared to the other samples.This hopes to provide useful information for optimizing the deformation parameters of the AZ42 alloys.
基金supported by the Key Project of Chinese Academy of Engineering(No.2019-XZ-11)the General Project of Chinese Academy of Engineering(No.2023-XY-18)+1 种基金the Open Fund of National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials of China(No.HKDNM201907)the Independent Project of State Key Laboratory of Powder Metallurgy,China。
文摘To tackle the common issue of green defects in material extrusion(MEX)additive manufacturing(AM)cemented carbides,warm isostatic pressing(WIP)was introduced to eliminate defects of MEX WC-9Co cemented carbide greens,thereby improving both microstructure uniformity and mechanical properties of sintered bodies.The results indicate that WIP reduces defects in MEX greens,thus decreasing the dimensions and numbers of defects,modifying shapes of pores within sintered bodies,while preserving surface quality and shape characteristics.Compared with WC-9Co prepared via MEX followed by debinding and sintering(DS),the hardness of WC-9Co prepared using MEX-WIP-DS does not change significantly,ranging HV_(30)1494-1508,the transverse rupture strength increases by up to 49.3%,reaching 2998-3514 MPa,and the fracture toughness remains high,ranging 14.8-17.0 MPa·m^(1/2).The mechanical properties surpass comparable cemented carbides fabricated through other AM methods and are comparable to those produced by powder metallurgy.The integration of green WIP into MEX-DS broadens the MEX processing window,and improves the overall mechanical properties of MEX AM WC-Co cemented carbides.
基金supported by the National Natural Science Foundation of China(No.52205393)the Natural Science Foundation of Shandong Province,China(No.ZR2022QE263)+1 种基金the Science and Technology Commission of Shanghai Municipality,Shanghai Rising-Star Program,China(No.23YF1413900)the Science and Technology Innovation Plan of Shanghai Science and Technology Commission,China(Nos.21010500800,23010501100).
文摘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{123}<111>and Cu{112}<111>evolve into S{123}<634>,and the Bs{011}<211>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.
基金the financial support from the National Natural Science Foundation of China(No.12164004)the Jiangxi Provincial Natural Science Foundation(Nos.20242BAB25210,20232BCJ25067,20232BAB214004 and 20224BAB204029)+2 种基金the Foundation of Education Department of Jiangxi Provincial(Nos.GJJ2201247 and GJJ211436)the Young and Middle-aged Teachers Education Scientific Research Project of Fujian Province(No.JAT231008)supported by Sinoma Institute of Materials Research(Guang Zhou)Co.,Ltd(SIMR).
文摘Mg-1.2Y-1.2Ni(at.%)alloy was extruded at 400℃with an extrusion ratio of 16:1 and different rates from 1 to 6 mm/s.The effect of extrusion rate on microstructure and mechanical properties of the Mg-1.2Y-1.2Ni alloy was systematically investigated.With the increase of extrusion rate,the average recrystallized grain size of Mg-1.2Y-1.2Ni alloy and mean particle diameter of Mg2Ni phase were increased,while the density of geometrically necessary dislocation and the intensity of the basal texture were decreased.When extrusion rate increases from 1 to 6 mm/s,the tensile yield strength(TYS)of asextruded Mg-1.2Y-1.2Ni alloy decreases from 501 to 281 MPa,while the elongation to failure increases from 1.5%to 6.2%.The Mg-1.2Y-1.2Ni alloy extruded at 3 mm/s obtained TYS of 421 MPa,the ultimate tensile strength(UTS)of 440 MPa and elongation to failure of 2.6%,respectively,exhibiting comprehensive mechanical properties with relatively good plasticity and ultrahigh strength.The ultrahigh TYS of 501 and 421 MPa was mainly due to the strengthening from ultrafine recrystallized grains,high volume fraction long period stacking ordered(LPSO)phases and high density dislocations.
基金supported by the National Key Research and Development Program of China (Grant No.2022YFB3706801)the National Natural Science Foundation of China (Grant Nos.U2341253,52371019,U2241232)+2 种基金the Dalian High-level Talents Innovation Support Program (Grant No.2021RD06)the Applied Basic Research Program of Liaoning Province (Grant No.2022JH2/101300003)the Natural Science Foundation of Liaoning Province (Grant Nos.2022-BS-262,JYTMS20230031)。
文摘Based on thermodynamic calculations and continuous rheological extrusion(CRE)technology,Al-Ti-V-B master alloys were designed and prepared.The morphology and the distribution of the refined phases in the master alloys were analyzed by XRD,SEM,and TEM.The effects of master alloy addition and holding time on the microstructure and mechanical properties of A356 alloy were investigated.Under the optimum refiner addition of 0.3wt.%and the holding time of 20 min,the average grain size of the refined A356 alloy is 151.8±9.11μm,89.62%lower than that of original A356 alloy.The tensile strength and elongation of as-cast A356refined alloy are 196.11 MPa and 5.75%,respectively.After T6 treatment,the tensile strength and elongation of A356 refined alloy are 290.1 MPa and 3.09%,respectively.The fracture morphology is characterized by a predominance of along-crystal fracture with a small amount of through-crystal fracture,attributed to the refined grains.Finer grains promote crack path deflection and localized plastic deformation,enhancing energy dissipation and reducing the tendency for brittle fracture.This study provides a novel approach to improving the mechanical properties of A356 alloy through grain refinement using CRE Al-Ti-V-B master alloy.
基金supported by the National Key Research and Development Program of China(No.2021YFB3701100)the Applied Basic Research Program Project of Liaoning Province,China(No.2023020253-JH2/1016)the Key Research and Development Plan of Shanxi Province,China(No.202102050201005).
文摘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{1012}tensile twins during the tensile deformation,resulting in a reduction in plasticity.
基金supported by the National Key R&D Program of China(No.2021YFB3701100)。
文摘The effects of trace Ag on the tensile strength and creep resistance of Mg-7.5Gd-1.5Y-0.4Zr(wt.%)extrusion bars were investigated at temperatures of 175-275℃,via tensile tests and creep tests,electron back-scatter diffraction,and transmission electron microscopy.Adding trace Ag improves the tensile strength and creep resistance of Mg-Gd-Y-Zr alloys at elevated temperatures.During the creep process,precipitate-free zones(PFZs)are formed near grain boundaries and perpendicular to the loading direction,while chain-likeβ′-Mg7RE precipitates are distributed in a special direction([1010])in grain interior.After adding Ag element,the creep resistance of the Mg-Gd-Y-Zr-Ag is improved due to the suppression of dislocation movement by the synergistic effect of narrower PFZs,finerβ′-Mg7RE precipitates in the grain interior and more stable β-Mg_(5)RE phase located on the grain boundaries.
基金supported by the general project of the National Natural Science Foundation of China(No.52071042)Chongqing Natural Science Foundation Project,China(Nos.CSTB2023NSCQ-MSX0079,cstc2021ycjh-bgzxm0148)Graduate Student Innovation Program of Chongqing University of Technology,China(No.gzlcx20232008).
文摘The Mg−Al composite rods of aluminum core-reinforced magnesium alloy were prepared by the extrusion−shear(ES)process,and the microstructure,deformation mechanism,and mechanical properties of the Mg−Al composite rods were investigated at different extrusion temperatures and shear stresses.The experimental results show that the proportion of dynamic recrystallization(DRX)and texture for Al and Mg alloys are controlled by the combination of temperature and shear stress.The texture type of the Al alloys exhibits slight variations at different temperatures.With the increase of temperature,the DRX behavior of Mg alloy shifts from discontinuous DRX(DDRX),continuous DRX(CDRX),and twin-induced DRX(TDRX)dominant to CDRX,the dislocation density in Mg alloy grains decreases significantly,and the average value of Schmid factor(SF)of the basalslip system increases.In particular,partial grains exhibit a distinct dominant slip system at 390℃.The hardness and thickness of the bonding layer,as well as the yield strength and elongation of the Mg alloy,reach their maximum at 360℃as a result of the intricate influence of the combined temperature and shear stress.
基金the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030006)the Guangdong Provincial Academy of Sciences Fund(2020GDASYL-20200101001)the Natural Science Foundation of Hubei Province,China(2023AFB1033).
文摘In this study,AZ91D(Mg-9Al-Zn)alloys reinforced with 2 vol%TC4(Ti-6Al-4V)particles fabricated by semi-solid stir casting were extruded at different ratios,resulting in observed grain refinement effects.The research findings demonstrate that both TC4 andβ-Mg_(17)Al_(12) phases contribute to promoting dynamic recrystallization(DRX)nucleation.With increasing extrusion ratio,theβ-phase(Mg_(17)Al_(12))gradually fractures into smaller particles,leading to progressive grain refinement.Furthermore,the transition from〈01-10〉fiber texture to non-basal texture in theα-Mg matrix after hot extrusion is attributed to improved DRX behavior and activation of non-basal slip.As the extrusion ratio increases,the tensile strength and elongation(EL)of TC4_(p)/AZ91D composite improve significantly,reaching optimum comprehensive mechanical properties at an extrusion of 40:1 with a yield strength(YS)of 257 MPa,an ultimate tensile strength(UTS)of 357 MPa,and an EL of 9.7%.This remarkable strengthening effect is primarily attributed toβ-phase reinforcement,grain refinement strengthening,and strain hardening.
基金supported by the Natural Science Foundation of China(32072139)Liaoning Province Natural Science Foundation Project(2022-MS-307).
文摘How to reduce peanut allergies has always been a main food safety concern.Plant polyphenol complex peanut sensitizing protein was proposed as a new desensitization strategy.Gallic acid(GA),as a natural plant polyphenol,has anti-inflammatory and immunomodulatory effects.Therefore,the aim of this study was to investigate the effect of GA on peanut protein(PP)sensitization under high moisture extrusion conditions.The contents of free sulfhydryl groups and disulfide bonds in the PP-GA complex were determined,and the structure of the complex was characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)and Fourier transform infrared spectroscopy.The results showed that with increasing GA content,the number of free sulfhydryl groups increased while the number of disulfide bonds decreased.The secondary structure of PP-GA showed that the random coils andβ-turns were transformed toα-helices andβ-sheets.A BALB/c mouse model was also established,wherein Al(OH)3 was used as an adjuvant when the complex was administered via intraperitoneal injection,and the mice showed mild allergic symptoms and a decreased immune organ index.In addition,the serum levels of specific antibodies(immunoglobulin E(IgE),immunoglobulin G1(IgG1),and immunoglobulin G2a(IgG2a)),cytokines(interleukin-5(IL-5),interleukin 13(IL-13),and interferon gamma(IFN-γ))and histamine were reduced.In summary,this study proved that GA can relieve the sensitization of PP induced by high moisture extrusion.
基金supported by the National Key R&D Program of China(No.2022YFA1005204l)。
文摘Silicone material extrusion(MEX)is widely used for processing liquids and pastes.Owing to the uneven linewidth and elastic extrusion deformation caused by material accumulation,products may exhibit geometric errors and performance defects,leading to a decline in product quality and affecting its service life.This study proposes a process parameter optimization method that considers the mechanical properties of printed specimens and production costs.To improve the quality of silicone printing samples and reduce production costs,three machine learning models,kernel extreme learning machine(KELM),support vector regression(SVR),and random forest(RF),were developed to predict these three factors.Training data were obtained through a complete factorial experiment.A new dataset is obtained using the Euclidean distance method,which assigns the elimination factor.It is trained with Bayesian optimization algorithms for parameter optimization,the new dataset is input into the improved double Gaussian extreme learning machine,and finally obtains the improved KELM model.The results showed improved prediction accuracy over SVR and RF.Furthermore,a multi-objective optimization framework was proposed by combining genetic algorithm technology with the improved KELM model.The effectiveness and reasonableness of the model algorithm were verified by comparing the optimized results with the experimental results.
基金supported by National Natural Science Foundation of China(Grant Nos.12202547,62461160259)Shaanxi Province Qingchuangyuan“Scientist and Engineering”Team Construction Project(Grant Nos.2022KXJ-102,2022KXJ-106)+1 种基金Fundamental Research Funds for the Central UniversitiesProgram for Innovation Team of Shaanxi Province(Grant No.2023-CX-TD-17).
文摘Variable material screw-based material extrusion(S-MEX)3D printing technology provides a novel approach for fabricating composites with continuous material gradients.Nevertheless,achieving precise alignment between the process parameters and material compositions is challenging because of fluctuations in the melt rheological state caused by material variations.In this study,an invertible extrusion prediction model for 0-40 wt% short carbon fiber reinforced polyether-ether-ketone(SCF/PEEK)in the S-MEX process was established using an invertible neural network(INN)that demonstrated the capabilities of forward flow rate prediction and inverse process optimization with accuracies of 0.852 and 0.877,respectively.Moreover,a strategy for adjusting the screw speeds using process parameters obtained from the INN was developed to maintain a consistent flow rate during the variable material printing process.Benefiting from uniform flow,the linewidth accuracy was improved by 77%,and the surface roughness was reduced by 51%.Adjusting the process parameters by using an INN offers significant potential for flow rate control and the enhancement of the overall performance of variable material 3D printing.
