Wire-arc directed energy deposition(wire-arc DED)enables the fabrication of large-scale metal components with rapid manufacturing ability and diverse material selection,making it a compelling technology in industries ...Wire-arc directed energy deposition(wire-arc DED)enables the fabrication of large-scale metal components with rapid manufacturing ability and diverse material selection,making it a compelling technology in industries and defenses.However,challenges in both macroscale and microscale defects still limit printed component widespread applications.Recent advances in automatic and intelligent technologies have brought a range of quality controllable strategies to the forefront.This review covers these new strategies for the printing component,including path planning,process monitoring,auxiliary processes,and post processing,while discussing the expectation for structure and quality improvement.In addition,the work brings new areas of intelligent wire-arc DED development,including advances in digital twin,visualization,and human-processing interaction to promote its performance.It is anticipated that a focus on intelligent system will be key to smart and high-quality manufacturing for future wire-arc DED.展开更多
In this work,the GW63K(Mg-6.54Gd-3.93Y-0.41Zr,wt.%)alloy wire was utilized as the feedstock material and the thin-walled component was fabricated using wire-arc additive manufacturing technology(WAAM).The microstructu...In this work,the GW63K(Mg-6.54Gd-3.93Y-0.41Zr,wt.%)alloy wire was utilized as the feedstock material and the thin-walled component was fabricated using wire-arc additive manufacturing technology(WAAM).The microstructural evolution during deposition and subsequent heat treatment was explained through multi-scale microstructural characterization techniques,and the impact of heat treatment on the strengthductility synergy of the deposited alloy was systematically compared.The results showed that the microstructure of the deposited sample was mainly composed of fine equiaxedα-Mg grains and Mg_(24)(Gd,Y)_(5) phase.The optimized solution heat treatment(450℃×2 h)had little effect on the grain size,but can effectively reduce the Mg_(24)(Gd,Y)_(5) eutectic phase on the grain boundary,resulting in a significant increase in elongation from 13.7% to 26.6%.After peak-aging treatment,the strength of the GW63K alloy increased to 370 MPa,which was significantly higher than the as-built state(267 MPa).The superior strength in this study is attributed to the refinement strengthening imparted by the fine microstructure inherited in the as-built GW63K alloy,as well as the precipitation strengthening due to the formation of dense β’precipitates with a pronounced plate-like aspect ratio.展开更多
Here we fabricate LA103Z Mg-Li alloy via wire-arc directed energy deposition(WA-DED),and subsequent aging treatment is employed to improve its mechanical property.Results show that a typical dual-phase microstructure ...Here we fabricate LA103Z Mg-Li alloy via wire-arc directed energy deposition(WA-DED),and subsequent aging treatment is employed to improve its mechanical property.Results show that a typical dual-phase microstructure is formed upon WA-DED,consisting of α-Mg,β-Li,AlLi and Li_(2)MgAl,with negligible porosity,and the core-shell Li_(2)MgAl/AlLi composite particles are also generated.After aging treatment,the microstructure is slightly coarsened,together with the precipitation of nano-sized D0_(3)-Mg_(3)Al particles,as well as the dissolution and the mergence of α-Mg phases.Negligible strength and ductility anisotropies are found for the as-deposited alloy.Significant strength increment is achieved via aging treatment,and the ultimate strength increases by~20%(~34 MPa),reaching 200±1 MPa.Both as-deposited and aged alloys show acceptable uniform elongation,with a transgranular fracture mode.Precipitation strengthening enabled by nano-sized D0_(3)-Mg_(3)Al precipitates is primarily responsible for the strength increment mediated by aging treatment.Grain refinement strengthening and solid solution strengthening provide additional contributions to the improved strength.Our work thus offers an applicable additive manufacturing pathway for the efficient and safety-guaranteed fabrication of Mg-Li alloy components with decent mechanical property.展开更多
In wire arc additive manufacturing(WAAM),a trade-off exists among deposition efficiency,microstructure,and mechanical properties.Addressing this challenge,this work proposes an innovative multi-objective optimization ...In wire arc additive manufacturing(WAAM),a trade-off exists among deposition efficiency,microstructure,and mechanical properties.Addressing this challenge,this work proposes an innovative multi-objective optimization framework tailored for WAAM of AZ31 magnesium alloy components,which integrates deposition efficiency and microstructure as coupled objectives and is resolved through the NSGA-Ⅱ algorithm.The proposed framework employs quadratic regression to correlate process parameters with deposition efficiency through geometric morphology mediation,while addressing uncertainties in WAAM by integrating theoretical insights with data-driven stacked ensemble learning for grain size prediction,establishing the hybrid physics-informed data method for WAAM microstructure prediction.The optimized process achieved a deposition rate of 6257 mm3/min,with effective width and average layer height maintained at 10.1 mm and 4.13 mm,respectively.Microstructural optimization produced a fine,uniform,fully equiaxed grain structure with an average grain size of 38μm.These findings underscore the significant industrial potential of intelligent optimization strategies in WAAM for manufacturing lightweight,high-performance components in aerospace and transportation sectors.展开更多
Research on the preparation of over-sized lightweight magnesium rare-earth(Mg-RE)components using the wire-arc directed energy deposition(WA-DED)is progressively gaining attention in the advanced manufacturing fields....Research on the preparation of over-sized lightweight magnesium rare-earth(Mg-RE)components using the wire-arc directed energy deposition(WA-DED)is progressively gaining attention in the advanced manufacturing fields.Herein,to satisfy the demand of ultrahigh load-bearing,the Zn-modified Mg-10Gd-2Y-1Zn-0.5Zr(GWZ1021K)alloy was designed for exploring the influence pattern of Zn element on the microstructure and properties of Mg-10Gd-2Y-0.5Zr(GW102K)with high RE content.Specifically,the Zn element enables finer and more homogeneous grains in the as-built GWZ1021K(18.2μm)than that in the as-built GW102K(23.9μm),owing to more nucleation sites and precipitation of nano-γ"and nano-γ’to impede grain growth during the intrinsic heat treatment.After solution treatment,the eutectic phases and RE-rich regions completely disappear in both GW102K and GWZ1021K,yielding elongations of up to 14.6%and 13.2%,respectively.Notably,the high-temperature solution process allows the growth of nano-γ"and nano-γ’,as well as the segregation of RE/Zn clusters and subsequent atomic rearrangements to form the 14H long period stacking ordered(LPSO)structures.Following peak-aging treatment,although dense nano-β’is precipitated in both GW102K and GWZ1021K,the Zn element facilitates the precipitation of nano-β_(1)to relieve the stress concentration induced by the two adjacent nano-β’.Generally,Zn elemental addition enhances strength with a sacrifice of ductility,which can be ascribed to the prismatic nano-β and basal 14H-LPSO structures work together to hinder the movement of both basal and non-basal dislocations.As a result,the GWZ1021K alloy achieves an ultra-high strength with an ultimate tensile strength of 403 MPa and a yield strength of 278 MPa,which far exceeds the reported average level of the WA-DED Mg-RE alloys.This study thus sheds new light on the fabrication of ultrahigh-strength Mg-RE alloy components by WA-DED process through appropriate composition modification.展开更多
The inherent hysteresis of NiTi alloy samples is one of the key factors limiting their elastocaloric cooling performance.However,reducing hysteresis often leads to a decrease in adiabatic temperature change(ΔT_(ad)),...The inherent hysteresis of NiTi alloy samples is one of the key factors limiting their elastocaloric cooling performance.However,reducing hysteresis often leads to a decrease in adiabatic temperature change(ΔT_(ad)),thereby hindering the application of NiTi alloys in the refrigeration field.Here,NiTi alloys with alternating high-Ni and low-Ni content were fabricated by tailoring heat input during the wire-arc directed energy deposition(DED)process,which modifies the Ni concentration gradient and enables the modulation of the elastocaloric cooling performance of NiTi alloys.The coefficient of performance of material(COP_(mat))of the high-Ni NiTi alloy samples is relatively high,but theirΔT_(ad) during deformation is lower.On the other hand,the low-Ni NiTi alloy samples,while exhibiting higherΔT_(ad),show poorer stability during cycling.Due to the synergistic effect of the microstructures in the high-Ni and low-Ni region,a favorable combination of low cyclic hysteresis and highΔT_(ad) were achieved in the composite NiTi samples.Additionally,the composite NiTi samples also demonstrate excellent cyclic stability,with a degradation rate of only 4%during the cycling process under a 2%strain condition.This study proposes a feasible approach for regulating the elastocaloric effect of NiTi alloys,paving the way for additive manufacturing to prepare elastocaloric cooling materials.展开更多
This study pioneers the integrated fabrication of magnesium corrugated-core sandwich structures using wire-arc directed energy deposition(WA-DED).Two sandwich structures—V-type and X-type—were designed with optimize...This study pioneers the integrated fabrication of magnesium corrugated-core sandwich structures using wire-arc directed energy deposition(WA-DED).Two sandwich structures—V-type and X-type—were designed with optimized deposition paths to achieve comparable grain morphology while enhancing strength.The compression properties and failure modes of the two corrugated-core sandwich structures were examined through quasi-static compression tests.Results showed that the V-type structure exhibited a higher specific compressive strength(93 MPa∙cm^(3)/g)than the X-type structure(72 MPa∙cm^(3)/g).Both finite element analysis and experimental compression tests indicated that failure occurred at the midsection of the corrugated core.This work offers valuable insights for the efficient fabrication of high-strength corrugated-core sandwich structures.展开更多
To expand the application of wire-arc additive manufacturing(WAAM)in aluminum alloy forming com-ponents,it is vitally important to reduce the porosity,refine microstructure,and thereby improve the mechanical propertie...To expand the application of wire-arc additive manufacturing(WAAM)in aluminum alloy forming com-ponents,it is vitally important to reduce the porosity,refine microstructure,and thereby improve the mechanical properties of the components.In this study,the interlayer friction stir processing(FSP)tech-nique was employed to assist the WAAM of 4043 Al-Si alloy,and the related effects on the microstruc-ture evolutions and mechanical properties of the fabricated builds were systematacially investigated.As compared to the conventional WAAM processing of Al-Si alloy,it was found that the introduction of in-terlayer FSP can effectively eliminate the pores,and both theα-Al dendrites and Si-rich eutectic network were severely broken up,leading to a remarkable enhancement in ductility and fatigue performance.The average yield strength(YS)and ultimate tensile strength(UTS)of the Al-based components produced by the combination of WAAM and interlayer FSP methods were 88 and 148 MPa,respectively.Meanwhile,the elongation(EL)of 37.5%and 28.8%can be achieved in the horizontal and vertical directions,respec-tively.Such anisotropy of EL was attributed to the inhomogeneous microstructure in the stir zone(SZ).Notably,the stress concentration can be effectively reduced by the elimination of porosity and Si-rich eu-tectic network fragmentation by the interlayer FSP,and thus the fatigue behavior was improved with the fatigue strength and elongation increased by∼28%and∼108.7%,respectively.It is anticipated that this study will provide a powerful strategy and theoretical guidance for the WAAM fabrication of Al-based alloy components with high ductility and fatigue performance.展开更多
The utilization of wire-arc additive manufacturing(WAAM)technology for the preparation of Al-Zn-Mg-Cu aluminum alloy has made some progress in recent years.However,the challenge still remains to achieve ultra-high str...The utilization of wire-arc additive manufacturing(WAAM)technology for the preparation of Al-Zn-Mg-Cu aluminum alloy has made some progress in recent years.However,the challenge still remains to achieve ultra-high strength(600 MPa)in WAAM.In this study,the crack-free Al-Zn-Mg-Cu-Sc thin-wall component with ultra-high strength was successfully fabricated by the cold metal transfer(CMT)pro-cess using a self-prepared 7B55-Sc filler wire.The microstructures of both as-deposited and T6 heat-treated samples were all composed of fine equiaxed grains with an average size of about 6.0μm.The primary Al_(3)(Sc,Zr)particles acted as heterogeneous nuclei to promote the formation of equiaxed grains and refine the microstructures during the solidification process.A large amount of continuous eutectic structures rich in Al,Zn,Mg,and Cu elements formed along the grain boundaries under the as-deposited condition,and the precipitated second phases within the grains mainly included the equilibriumηphase,metastableηphase and large-sized T phase.After T6 heat treatment,the majority of the second phases originally distributed within grains and along grain boundaries were dissolved into the Al matrix,and a large amount of fine GP zones,ηphase and secondary Al_(3)(Sc,Zr)particles were precipitated within the grains during the aging process.The tensile strength reached a recorded level of 618 MPa in the hori-zontal direction after T6 heat treatment,which was considered a breakthrough for the manufacturing of 600 MPa grade aluminum alloy by WAAM.展开更多
Here,we compare the porosity,microstructure and mechanical property of 4047 Al–Si alloys prepared by wire-arc additive manufacturing(WAAM)and conventional casting.X-ray microscopy reveals that WAAM causes a higher vo...Here,we compare the porosity,microstructure and mechanical property of 4047 Al–Si alloys prepared by wire-arc additive manufacturing(WAAM)and conventional casting.X-ray microscopy reveals that WAAM causes a higher volume fraction of gas pores in comparison with conventional casting.Effective refi nements ofα-Al dendrites,eutectic Si particles and Ferich intermetallic compounds are achieved by WAAM,resulting from its rapid solidifi cation process.Both ultimate tensile strength(UTS,up to 205.6 MPa)and yield stress(YS,up to 98.0 MPa)are improved by WAAM at the expense of elongation after fracture.The mechanical property anisotropy between scanning direction and build direction is minimal for alloys via WAAM.Additional microstructure refi nement and strength enhancement are enabled by increasing the travel speed of welding torch from 300 to 420 mm/min.展开更多
In recent years,wire-arc directed energy deposition(wa DED),which is also commonly known as wire-arc additive manufacturing(WAAM),has emerged as a promising new fabrication technique for magnesium alloys.The major rea...In recent years,wire-arc directed energy deposition(wa DED),which is also commonly known as wire-arc additive manufacturing(WAAM),has emerged as a promising new fabrication technique for magnesium alloys.The major reason for this is the possibility of producing parts with a complex geometry as well as a fine-grained microstructure.While the process has been shown to be applicable for Mg-Al-Zn alloys,there is still a lack of knowledge in terms of the influence of the WAAM process on the age-hardening response.Consequently,this study deals with the aging response of a WAAM AZ91 alloy.In order to fully understand the mechanisms during aging,first,the as-built condition was analyzed by means of high-energy X-ray diffraction(HEXRD)and scanning electron microscopy.These investigations revealed a finegrained,equiaxed microstructure with adjacent areas of alternating Al content.Subsequently,the difference between single-and double-step aging as well as conventional and direct aging was studied on the as-built WAAM AZ91 alloy for the first time.The aging response during the various heat treatments was monitored via in situ HEXRD experiments.Corroborating electron microscopy and hardness studies were conducted.The results showed that the application of a double-step aging heat treatment at 325℃with pre-aging at 250℃slightly improves the mechanical properties when compared to the single-step heat treatment at 325℃.However,the hardness decreases considerably after the pre-aging step.Thus,aging at lower temperatures is preferable within the investigated temperature range of 250-325℃.Moreover,no significant difference between the conventionally aged and directly aged samples was found.Lastly,the specimens showed enhanced precipitation kinetics during aging as compared to cast samples.This could be attributed to a higher amount of nucleation sites and the particular temperature profile of the solution heat treatment.展开更多
Mg-Gd-Y-Zr alloy,as a typical magnesium rare-earth(Mg-RE)alloy,is gaining popularity in the advanced equipment manufacturing fields owing to its noticeable age-hardening properties and high specific strength.However,i...Mg-Gd-Y-Zr alloy,as a typical magnesium rare-earth(Mg-RE)alloy,is gaining popularity in the advanced equipment manufacturing fields owing to its noticeable age-hardening properties and high specific strength.However,it is extremely challenging to prepare wrought components with large dimensions and complex shapes because of the poor room-temperature processability of Mg-Gd-Y-Zr alloy.Herein,we report a wire-arc directed energy deposited(DED)Mg-10.45Gd-2.27Y-0.52Zr(wt.%,GW102K)alloy with high RE content presenting a prominent combination of strength and ductility,realized by tailored nanoprecipitates through an optimized heat treatment procedure.Specifically,the solution-treated sample exhibits excellent ductility with an elongation(EL)of(14.6±0.1)%,while the aging-treated sample at 200°C for 58 h achieves an ultra-high ultimate tensile strength(UTS)of(371±1.5)MPa.Besides,the aging-treated sample at 250°C for 16 h attains a good strength-ductility synergy with a UTS of(316±2.1)MPa and a EL of(8.5±0.1)%.Particularly,the evolution mechanisms of precipitation response induced by various aging parameters and deformation behavior caused by nanoprecipitates type were also systematically revealed.The excellent ductility resulted from coordinating localized strains facilitated by active slip activity.And the ultra-high strength should be ascribed to the dense nano-β'hampering dislocation motion.Additionally,the shearable nano-β1 contributed to the good strength-ductility synergy.This work thus offers insightful understanding into the nanoprecipitates manipulation and performance tailoring for the wire-arc DED preparation of large-sized Mg-Gd-Y-Zr components with complex geometries.展开更多
Submerged friction stir processing(SFSP)with flowing water was employed to alleviate the porosities and coarse-grained structure introduced by wire-arc manufacturing.As a result,uniform and ultrafine grained(UFG)struc...Submerged friction stir processing(SFSP)with flowing water was employed to alleviate the porosities and coarse-grained structure introduced by wire-arc manufacturing.As a result,uniform and ultrafine grained(UFG)structure with average grain size of 0.83μm was achieved with the help of sharply reduced heat input and holding time at elevated temperature.The optimized UFG structure enabled a superior combination of strength and ductility with high ultimate tensile strength and elongation of 273.17 MPa and 15.39%.Specifically,grain refinement strengthening and decentralized θ(Al_(2)Cu)phase in the sample subjected to SFSP made great contributions to the enhanced strength.In addition,the decrease in residual stresses and removal of pores substantially enhance the ductility.High rates of cooling and low temperature cycling,which are facilitated by the water-cooling environment throughout the machining process,are vital in obtaining superior microstructures.This work provides a new method for developing a uniform and UFG structure with excellent mechanical properties.展开更多
Here we propose to employ wire-arc directed energy deposition(WA-DED) to tune the microstructure and the mechanical property of Mg-Al-Si alloys, on the basis of its sub-rapid solidification effect. According to finite...Here we propose to employ wire-arc directed energy deposition(WA-DED) to tune the microstructure and the mechanical property of Mg-Al-Si alloys, on the basis of its sub-rapid solidification effect. According to finite element analysis, WA-DED shows higher cooling rate than conventional casting, reaching 598.3 K/s for Mg-Al-Si alloy, and the lower heat input, the larger cooling rate of WA-DED. Significant microstructure refinement is thus achieved, with reduced grain size and Mg_(2)Si particle diameter. The transition from hypereutectic to fully eutectic microstructure is triggered by reducing the heat input. Compared with the as-cast alloy, WA-DED alloys demonstrate higher ultimate tensile strengths(UTS) at both room-and high-temperature(150℃) properties, increasing by 50.1% and 30.3%, respectively. The superior strength-ductility synergy for Mg-Al-Si alloys results from the microstructure tuning via sub-rapid solidification of WA-DED.展开更多
Recently,the application of wire-arc additive manufacturing(WAAM)for the production of metallic products is gaining traction.WAAM is associated with the direct energy deposition technique and therefore has a higher de...Recently,the application of wire-arc additive manufacturing(WAAM)for the production of metallic products is gaining traction.WAAM is associated with the direct energy deposition technique and therefore has a higher deposition rate(approximately 4 kg/h).For this reason,it is of greater interest than powder-based additive manufacturing techniques.Industrial applications such as marine and offshore structures and pressure vessels for space programs commonly utilize high-strength low-alloy(HSLA)steel.HSLA steel components produced by casting methods exhibit defects due to oxidation.Therefore,cold metal transfer(CMT)-WAAM was adopted in this study to fabricate HSLA steel components.The metallurgical properties were analyzed using microscopic and diffraction techniques.The effects of the evolved microstructures on mechanical properties,such as strength,microhardness,and elongation to fracture,were evaluated.To analyze and test the structure,two regions were selected,namely,top and bottom.Microstructural analyses revealed that both regions were primarily composed of acicular ferrite,polygonal ferrite,and bainitic structures.The bottom region exhibited superior mechanical properties compared with the top region.The improved strength at the bottom region can be ascribed to the formation of a high density of dislocations and finer grains.展开更多
Conventional cast Al-Ce alloys are challenged by the increasing demand for improved mechanical properties.To address this issue,in this study,wire-arc directed energy deposition(WA-DED)is employed for the fabrication ...Conventional cast Al-Ce alloys are challenged by the increasing demand for improved mechanical properties.To address this issue,in this study,wire-arc directed energy deposition(WA-DED)is employed for the fabrication of Al-15Ce-3Mg(wt%)alloy components.We aimed to tune the microstructure and mechanical properties via the inherent sub-rapid-solidification effect of WA-DED.In addition to significant microstructure refinement,a decrease in arc heat input leads to a larger cooling rate,up to 346℃/s,and triggers the transition from hyper-eutectic to near-eutecticα-Al/Al_(11)Ce_(3)microstructures with the suppression of primary Al_(11)Ce_(3)intermetallics.Such microstructural modification improves the mechanical properties,resulting in higher yield and ultimate tensile strengths than those of the as-cast counterpart alloy.The fracture process involves the formation of dim-ples around Al_(11)Ce_(3),cracking of large Al_(11)Ce_(3) particles,and growth,merging,and fracture of pores.The strength increment is mainly contributed by particle-size strengthening mediated by microstructure refinement as well as the targeted formation of near-eutecticα-Al/Al_(11)Ce_(3)microstructures.展开更多
This study investigated the effect of thermal cycles on Cu-modified Ti64 thin-walled components deposited using the wire-arc directed energy deposition(wire-arc DED)process.For the samples before and after experiencin...This study investigated the effect of thermal cycles on Cu-modified Ti64 thin-walled components deposited using the wire-arc directed energy deposition(wire-arc DED)process.For the samples before and after experiencing thermal cycles,it was found that both microstructures consisted of priorβ,grain boundaryα(GBα),and basketweave structures containingα+βlamellae.Thermal cycles realized the refinement ofαlaths,the coarsening of priorβgrains andβlaths,while the size and morphology of continuously distributed GBαremained unchanged.The residualβcontent was increased after thermal cycles.Compared with the heat-treated sample with nanoscale Ti2Cu formed,short residence time in high temperature caused by the rapid cooling rate of thermal cycles restricted Ti2Cu formation.No formation of brittle Ti2Cu means that only grain refinement strengthening and solid-solution strengthening matter.The yield strength increased from 809.9 to 910.85 MPa(12.46%increase).Among them,the main contribution from solid solution strengthening(~51 MPa)was due to the elemental redistribution effect betweenαandβphases caused by thermal cycles through quantitative analysis.The ultimate tensile strength increased from 918.5 to 974.22 MPa(6.1%increase),while fracture elongation increased from 6.78 to 10.66%(57.23%increase).Grain refinement ofαlaths,the promotedα′martensite decomposition,decreased aspect ratio,decreased Schmid factor,and local misorientation change ofαlaths are the main factors in improved ductility.Additionally,although the fracture modes of the samples in the top and middle regions are both brittle-ductile mixed fracture mode,the thermal cycles still contributed to an improvement in tensile ductility.展开更多
Wire-arc additive manufacture(WAAM)has great potential for manufacturing of Al-Cu components.However,inferior mechanical properties of WAAM deposited material restrict its industrial application.Inter-layer cold rolli...Wire-arc additive manufacture(WAAM)has great potential for manufacturing of Al-Cu components.However,inferior mechanical properties of WAAM deposited material restrict its industrial application.Inter-layer cold rolling and thermo-mechanical heat treatment(T8)with pre-stretching deformation between solution and aging treatment were adopted in this study.Their effects on hardness,mechanical properties and microstructure were analyzed and compared to the conventional heat treatment(T6).The results show that cold rolling increases the hardness and strengths,which further increase with T8 treatment.The ultimate tensile strength(UTS)of 513 MPa and yield stress(YS)of 413 MPa can be obtained in the inter-layer cold-rolled sample with T8 treatment,which is much higher than that in the as-deposited samples.The cold-rolled samples show higher elongation than that of as-deposited ones due to significant elimination of porosity in cold rolling;while both the T6 and T8 treatments decrease the elongation.The cold rolling and pre-stretching deformation both contribute to the formation of dense and dispersive precipitatedθ′phases,which inhibits the dislocation movement and enhances the strengths;as a result,T8 treatment shows better strengthening effect than the T6 treatment.The strengthening mechanism was analyzed and it was mainly related to work hardening and precipitation strengthening.展开更多
Wire-arc directed energy deposition(WA-DED)has emerged as a transformative technology for producing large-scale metal components owing to its capacity for cost-effective fabrication and suitable deposition rates.Recen...Wire-arc directed energy deposition(WA-DED)has emerged as a transformative technology for producing large-scale metal components owing to its capacity for cost-effective fabrication and suitable deposition rates.Recently,the focus has shifted to the WA-DED of magnesium alloys,which are promising lightweight structural materials in the aerospace transportation and military industries.This article systematically reviews recent advancements in magnesium alloys fabricated using WA-DED.It discusses aspects such as forming quality,internal defects,microstructural evolution,and mechanical properties.Prevalent internal defects such as pores and cracks in WA-DED magnesium alloys are identified and characterized.Additionally,strategies for enhancing the manufacturing quality are elucidated.Furthermore,this article comprehensively explores the underlying mechanisms of the interplay among process parameters,internal defects,and microstructural heterogeneity.The main objective is to provide insights into and strategies for defect elimination,microstructural homogenization,and property enhancement.Finally,some perspectives are proposed for further progress in the application of WA-DED magnesium alloy components for superior performance.展开更多
基金fully appreciate financial support from NingXia Natural Science Foundation for Outstanding Young Scholar(No.2024AAC04002)CAS“Light of West China”Program,National Natural Science Foundation of China(Key Program,No.12232013)Natural Science Foundation of Ningxia(Key Program,No.2022AAC2003)。
文摘Wire-arc directed energy deposition(wire-arc DED)enables the fabrication of large-scale metal components with rapid manufacturing ability and diverse material selection,making it a compelling technology in industries and defenses.However,challenges in both macroscale and microscale defects still limit printed component widespread applications.Recent advances in automatic and intelligent technologies have brought a range of quality controllable strategies to the forefront.This review covers these new strategies for the printing component,including path planning,process monitoring,auxiliary processes,and post processing,while discussing the expectation for structure and quality improvement.In addition,the work brings new areas of intelligent wire-arc DED development,including advances in digital twin,visualization,and human-processing interaction to promote its performance.It is anticipated that a focus on intelligent system will be key to smart and high-quality manufacturing for future wire-arc DED.
基金Supported by the Industrial Collaborative Innovation Project of Shanghai(Grant No XTCX-KJ-2022-2-11)the National Natural Science Foundation of China(Grant No52073176)。
文摘In this work,the GW63K(Mg-6.54Gd-3.93Y-0.41Zr,wt.%)alloy wire was utilized as the feedstock material and the thin-walled component was fabricated using wire-arc additive manufacturing technology(WAAM).The microstructural evolution during deposition and subsequent heat treatment was explained through multi-scale microstructural characterization techniques,and the impact of heat treatment on the strengthductility synergy of the deposited alloy was systematically compared.The results showed that the microstructure of the deposited sample was mainly composed of fine equiaxedα-Mg grains and Mg_(24)(Gd,Y)_(5) phase.The optimized solution heat treatment(450℃×2 h)had little effect on the grain size,but can effectively reduce the Mg_(24)(Gd,Y)_(5) eutectic phase on the grain boundary,resulting in a significant increase in elongation from 13.7% to 26.6%.After peak-aging treatment,the strength of the GW63K alloy increased to 370 MPa,which was significantly higher than the as-built state(267 MPa).The superior strength in this study is attributed to the refinement strengthening imparted by the fine microstructure inherited in the as-built GW63K alloy,as well as the precipitation strengthening due to the formation of dense β’precipitates with a pronounced plate-like aspect ratio.
基金supported by the National Natural Science Foundation of China(52475320).
文摘Here we fabricate LA103Z Mg-Li alloy via wire-arc directed energy deposition(WA-DED),and subsequent aging treatment is employed to improve its mechanical property.Results show that a typical dual-phase microstructure is formed upon WA-DED,consisting of α-Mg,β-Li,AlLi and Li_(2)MgAl,with negligible porosity,and the core-shell Li_(2)MgAl/AlLi composite particles are also generated.After aging treatment,the microstructure is slightly coarsened,together with the precipitation of nano-sized D0_(3)-Mg_(3)Al particles,as well as the dissolution and the mergence of α-Mg phases.Negligible strength and ductility anisotropies are found for the as-deposited alloy.Significant strength increment is achieved via aging treatment,and the ultimate strength increases by~20%(~34 MPa),reaching 200±1 MPa.Both as-deposited and aged alloys show acceptable uniform elongation,with a transgranular fracture mode.Precipitation strengthening enabled by nano-sized D0_(3)-Mg_(3)Al precipitates is primarily responsible for the strength increment mediated by aging treatment.Grain refinement strengthening and solid solution strengthening provide additional contributions to the improved strength.Our work thus offers an applicable additive manufacturing pathway for the efficient and safety-guaranteed fabrication of Mg-Li alloy components with decent mechanical property.
基金supported by the National Natural Science Foundation of China(Nos.52475317 and 52305331).
文摘In wire arc additive manufacturing(WAAM),a trade-off exists among deposition efficiency,microstructure,and mechanical properties.Addressing this challenge,this work proposes an innovative multi-objective optimization framework tailored for WAAM of AZ31 magnesium alloy components,which integrates deposition efficiency and microstructure as coupled objectives and is resolved through the NSGA-Ⅱ algorithm.The proposed framework employs quadratic regression to correlate process parameters with deposition efficiency through geometric morphology mediation,while addressing uncertainties in WAAM by integrating theoretical insights with data-driven stacked ensemble learning for grain size prediction,establishing the hybrid physics-informed data method for WAAM microstructure prediction.The optimized process achieved a deposition rate of 6257 mm3/min,with effective width and average layer height maintained at 10.1 mm and 4.13 mm,respectively.Microstructural optimization produced a fine,uniform,fully equiaxed grain structure with an average grain size of 38μm.These findings underscore the significant industrial potential of intelligent optimization strategies in WAAM for manufacturing lightweight,high-performance components in aerospace and transportation sectors.
基金National Natural Science Foundation of China(523B2049,52275374,52205414)Xi’an Jiaotong University Basic Research Funds for Freedom of Exploration and InnovationStudent Programs(xzy022023066)The Xiaomi Foundation through Xiaomi Young Scholar Program.
文摘Research on the preparation of over-sized lightweight magnesium rare-earth(Mg-RE)components using the wire-arc directed energy deposition(WA-DED)is progressively gaining attention in the advanced manufacturing fields.Herein,to satisfy the demand of ultrahigh load-bearing,the Zn-modified Mg-10Gd-2Y-1Zn-0.5Zr(GWZ1021K)alloy was designed for exploring the influence pattern of Zn element on the microstructure and properties of Mg-10Gd-2Y-0.5Zr(GW102K)with high RE content.Specifically,the Zn element enables finer and more homogeneous grains in the as-built GWZ1021K(18.2μm)than that in the as-built GW102K(23.9μm),owing to more nucleation sites and precipitation of nano-γ"and nano-γ’to impede grain growth during the intrinsic heat treatment.After solution treatment,the eutectic phases and RE-rich regions completely disappear in both GW102K and GWZ1021K,yielding elongations of up to 14.6%and 13.2%,respectively.Notably,the high-temperature solution process allows the growth of nano-γ"and nano-γ’,as well as the segregation of RE/Zn clusters and subsequent atomic rearrangements to form the 14H long period stacking ordered(LPSO)structures.Following peak-aging treatment,although dense nano-β’is precipitated in both GW102K and GWZ1021K,the Zn element facilitates the precipitation of nano-β_(1)to relieve the stress concentration induced by the two adjacent nano-β’.Generally,Zn elemental addition enhances strength with a sacrifice of ductility,which can be ascribed to the prismatic nano-β and basal 14H-LPSO structures work together to hinder the movement of both basal and non-basal dislocations.As a result,the GWZ1021K alloy achieves an ultra-high strength with an ultimate tensile strength of 403 MPa and a yield strength of 278 MPa,which far exceeds the reported average level of the WA-DED Mg-RE alloys.This study thus sheds new light on the fabrication of ultrahigh-strength Mg-RE alloy components by WA-DED process through appropriate composition modification.
基金financially supported by the National Natural Science Foundation of China(Nos.52275374 and 52205414)the Key Research and Development Projects of Shaanxi Province(No.2023-YBGY-361)+1 种基金the Xi’an Jiaotong University Basic Research Funds for Freedom of Exploration and Innovation-Student Programs(No.xzy022024099)the Taihu Lake Innovation Fund for the School of Future Technology of Xi’an Jiaotong University.
文摘The inherent hysteresis of NiTi alloy samples is one of the key factors limiting their elastocaloric cooling performance.However,reducing hysteresis often leads to a decrease in adiabatic temperature change(ΔT_(ad)),thereby hindering the application of NiTi alloys in the refrigeration field.Here,NiTi alloys with alternating high-Ni and low-Ni content were fabricated by tailoring heat input during the wire-arc directed energy deposition(DED)process,which modifies the Ni concentration gradient and enables the modulation of the elastocaloric cooling performance of NiTi alloys.The coefficient of performance of material(COP_(mat))of the high-Ni NiTi alloy samples is relatively high,but theirΔT_(ad) during deformation is lower.On the other hand,the low-Ni NiTi alloy samples,while exhibiting higherΔT_(ad),show poorer stability during cycling.Due to the synergistic effect of the microstructures in the high-Ni and low-Ni region,a favorable combination of low cyclic hysteresis and highΔT_(ad) were achieved in the composite NiTi samples.Additionally,the composite NiTi samples also demonstrate excellent cyclic stability,with a degradation rate of only 4%during the cycling process under a 2%strain condition.This study proposes a feasible approach for regulating the elastocaloric effect of NiTi alloys,paving the way for additive manufacturing to prepare elastocaloric cooling materials.
基金supported by JCKY Project(Grant No.JCKY2023602B012).
文摘This study pioneers the integrated fabrication of magnesium corrugated-core sandwich structures using wire-arc directed energy deposition(WA-DED).Two sandwich structures—V-type and X-type—were designed with optimized deposition paths to achieve comparable grain morphology while enhancing strength.The compression properties and failure modes of the two corrugated-core sandwich structures were examined through quasi-static compression tests.Results showed that the V-type structure exhibited a higher specific compressive strength(93 MPa∙cm^(3)/g)than the X-type structure(72 MPa∙cm^(3)/g).Both finite element analysis and experimental compression tests indicated that failure occurred at the midsection of the corrugated core.This work offers valuable insights for the efficient fabrication of high-strength corrugated-core sandwich structures.
文摘To expand the application of wire-arc additive manufacturing(WAAM)in aluminum alloy forming com-ponents,it is vitally important to reduce the porosity,refine microstructure,and thereby improve the mechanical properties of the components.In this study,the interlayer friction stir processing(FSP)tech-nique was employed to assist the WAAM of 4043 Al-Si alloy,and the related effects on the microstruc-ture evolutions and mechanical properties of the fabricated builds were systematacially investigated.As compared to the conventional WAAM processing of Al-Si alloy,it was found that the introduction of in-terlayer FSP can effectively eliminate the pores,and both theα-Al dendrites and Si-rich eutectic network were severely broken up,leading to a remarkable enhancement in ductility and fatigue performance.The average yield strength(YS)and ultimate tensile strength(UTS)of the Al-based components produced by the combination of WAAM and interlayer FSP methods were 88 and 148 MPa,respectively.Meanwhile,the elongation(EL)of 37.5%and 28.8%can be achieved in the horizontal and vertical directions,respec-tively.Such anisotropy of EL was attributed to the inhomogeneous microstructure in the stir zone(SZ).Notably,the stress concentration can be effectively reduced by the elimination of porosity and Si-rich eu-tectic network fragmentation by the interlayer FSP,and thus the fatigue behavior was improved with the fatigue strength and elongation increased by∼28%and∼108.7%,respectively.It is anticipated that this study will provide a powerful strategy and theoretical guidance for the WAAM fabrication of Al-based alloy components with high ductility and fatigue performance.
基金financially supported by the China Scholarship Council(No.202208200005)Liaoning Province Excellent Youth Foundation(No.2021-YQ-01)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.Y2021061).
文摘The utilization of wire-arc additive manufacturing(WAAM)technology for the preparation of Al-Zn-Mg-Cu aluminum alloy has made some progress in recent years.However,the challenge still remains to achieve ultra-high strength(600 MPa)in WAAM.In this study,the crack-free Al-Zn-Mg-Cu-Sc thin-wall component with ultra-high strength was successfully fabricated by the cold metal transfer(CMT)pro-cess using a self-prepared 7B55-Sc filler wire.The microstructures of both as-deposited and T6 heat-treated samples were all composed of fine equiaxed grains with an average size of about 6.0μm.The primary Al_(3)(Sc,Zr)particles acted as heterogeneous nuclei to promote the formation of equiaxed grains and refine the microstructures during the solidification process.A large amount of continuous eutectic structures rich in Al,Zn,Mg,and Cu elements formed along the grain boundaries under the as-deposited condition,and the precipitated second phases within the grains mainly included the equilibriumηphase,metastableηphase and large-sized T phase.After T6 heat treatment,the majority of the second phases originally distributed within grains and along grain boundaries were dissolved into the Al matrix,and a large amount of fine GP zones,ηphase and secondary Al_(3)(Sc,Zr)particles were precipitated within the grains during the aging process.The tensile strength reached a recorded level of 618 MPa in the hori-zontal direction after T6 heat treatment,which was considered a breakthrough for the manufacturing of 600 MPa grade aluminum alloy by WAAM.
基金the financial support of the China Postdoctoral Science Foundation(No.2021M690384)the Beijing Institute of Technology Research Fund Program for Young Scholars。
文摘Here,we compare the porosity,microstructure and mechanical property of 4047 Al–Si alloys prepared by wire-arc additive manufacturing(WAAM)and conventional casting.X-ray microscopy reveals that WAAM causes a higher volume fraction of gas pores in comparison with conventional casting.Effective refi nements ofα-Al dendrites,eutectic Si particles and Ferich intermetallic compounds are achieved by WAAM,resulting from its rapid solidifi cation process.Both ultimate tensile strength(UTS,up to 205.6 MPa)and yield stress(YS,up to 98.0 MPa)are improved by WAAM at the expense of elongation after fracture.The mechanical property anisotropy between scanning direction and build direction is minimal for alloys via WAAM.Additional microstructure refi nement and strength enhancement are enabled by increasing the travel speed of welding torch from 300 to 420 mm/min.
基金supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020the financial support of the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(Grant No.771146 TOUGHIT)funded within the AIT’s strategic research portfolio 2022 and by the European Commission within the framework INTERREG V-A Austria–Czech Republic in the project“ReMaP“(Interreg project no.ATCZ229)。
文摘In recent years,wire-arc directed energy deposition(wa DED),which is also commonly known as wire-arc additive manufacturing(WAAM),has emerged as a promising new fabrication technique for magnesium alloys.The major reason for this is the possibility of producing parts with a complex geometry as well as a fine-grained microstructure.While the process has been shown to be applicable for Mg-Al-Zn alloys,there is still a lack of knowledge in terms of the influence of the WAAM process on the age-hardening response.Consequently,this study deals with the aging response of a WAAM AZ91 alloy.In order to fully understand the mechanisms during aging,first,the as-built condition was analyzed by means of high-energy X-ray diffraction(HEXRD)and scanning electron microscopy.These investigations revealed a finegrained,equiaxed microstructure with adjacent areas of alternating Al content.Subsequently,the difference between single-and double-step aging as well as conventional and direct aging was studied on the as-built WAAM AZ91 alloy for the first time.The aging response during the various heat treatments was monitored via in situ HEXRD experiments.Corroborating electron microscopy and hardness studies were conducted.The results showed that the application of a double-step aging heat treatment at 325℃with pre-aging at 250℃slightly improves the mechanical properties when compared to the single-step heat treatment at 325℃.However,the hardness decreases considerably after the pre-aging step.Thus,aging at lower temperatures is preferable within the investigated temperature range of 250-325℃.Moreover,no significant difference between the conventionally aged and directly aged samples was found.Lastly,the specimens showed enhanced precipitation kinetics during aging as compared to cast samples.This could be attributed to a higher amount of nucleation sites and the particular temperature profile of the solution heat treatment.
基金National Natural Science Foundation of China (52275374, 52205414)Xi’an Jiaotong University Basic Research Funds for Freedom of Exploration and Innovation-Student Programs (xzy022023066)+3 种基金Key Research and Development Projects of Shaanxi Province (2023-YBGY-361)Young Elite Scientists Sponsorship Program by CAST (2021QNRC001)State Key Laboratory for Mechanical Behavior of Materials (20212311)Xiaomi Foundation through Xiaomi Young Scholar Program
文摘Mg-Gd-Y-Zr alloy,as a typical magnesium rare-earth(Mg-RE)alloy,is gaining popularity in the advanced equipment manufacturing fields owing to its noticeable age-hardening properties and high specific strength.However,it is extremely challenging to prepare wrought components with large dimensions and complex shapes because of the poor room-temperature processability of Mg-Gd-Y-Zr alloy.Herein,we report a wire-arc directed energy deposited(DED)Mg-10.45Gd-2.27Y-0.52Zr(wt.%,GW102K)alloy with high RE content presenting a prominent combination of strength and ductility,realized by tailored nanoprecipitates through an optimized heat treatment procedure.Specifically,the solution-treated sample exhibits excellent ductility with an elongation(EL)of(14.6±0.1)%,while the aging-treated sample at 200°C for 58 h achieves an ultra-high ultimate tensile strength(UTS)of(371±1.5)MPa.Besides,the aging-treated sample at 250°C for 16 h attains a good strength-ductility synergy with a UTS of(316±2.1)MPa and a EL of(8.5±0.1)%.Particularly,the evolution mechanisms of precipitation response induced by various aging parameters and deformation behavior caused by nanoprecipitates type were also systematically revealed.The excellent ductility resulted from coordinating localized strains facilitated by active slip activity.And the ultra-high strength should be ascribed to the dense nano-β'hampering dislocation motion.Additionally,the shearable nano-β1 contributed to the good strength-ductility synergy.This work thus offers insightful understanding into the nanoprecipitates manipulation and performance tailoring for the wire-arc DED preparation of large-sized Mg-Gd-Y-Zr components with complex geometries.
文摘Submerged friction stir processing(SFSP)with flowing water was employed to alleviate the porosities and coarse-grained structure introduced by wire-arc manufacturing.As a result,uniform and ultrafine grained(UFG)structure with average grain size of 0.83μm was achieved with the help of sharply reduced heat input and holding time at elevated temperature.The optimized UFG structure enabled a superior combination of strength and ductility with high ultimate tensile strength and elongation of 273.17 MPa and 15.39%.Specifically,grain refinement strengthening and decentralized θ(Al_(2)Cu)phase in the sample subjected to SFSP made great contributions to the enhanced strength.In addition,the decrease in residual stresses and removal of pores substantially enhance the ductility.High rates of cooling and low temperature cycling,which are facilitated by the water-cooling environment throughout the machining process,are vital in obtaining superior microstructures.This work provides a new method for developing a uniform and UFG structure with excellent mechanical properties.
基金National Natural Science Foundation of China (52105319)。
文摘Here we propose to employ wire-arc directed energy deposition(WA-DED) to tune the microstructure and the mechanical property of Mg-Al-Si alloys, on the basis of its sub-rapid solidification effect. According to finite element analysis, WA-DED shows higher cooling rate than conventional casting, reaching 598.3 K/s for Mg-Al-Si alloy, and the lower heat input, the larger cooling rate of WA-DED. Significant microstructure refinement is thus achieved, with reduced grain size and Mg_(2)Si particle diameter. The transition from hypereutectic to fully eutectic microstructure is triggered by reducing the heat input. Compared with the as-cast alloy, WA-DED alloys demonstrate higher ultimate tensile strengths(UTS) at both room-and high-temperature(150℃) properties, increasing by 50.1% and 30.3%, respectively. The superior strength-ductility synergy for Mg-Al-Si alloys results from the microstructure tuning via sub-rapid solidification of WA-DED.
文摘Recently,the application of wire-arc additive manufacturing(WAAM)for the production of metallic products is gaining traction.WAAM is associated with the direct energy deposition technique and therefore has a higher deposition rate(approximately 4 kg/h).For this reason,it is of greater interest than powder-based additive manufacturing techniques.Industrial applications such as marine and offshore structures and pressure vessels for space programs commonly utilize high-strength low-alloy(HSLA)steel.HSLA steel components produced by casting methods exhibit defects due to oxidation.Therefore,cold metal transfer(CMT)-WAAM was adopted in this study to fabricate HSLA steel components.The metallurgical properties were analyzed using microscopic and diffraction techniques.The effects of the evolved microstructures on mechanical properties,such as strength,microhardness,and elongation to fracture,were evaluated.To analyze and test the structure,two regions were selected,namely,top and bottom.Microstructural analyses revealed that both regions were primarily composed of acicular ferrite,polygonal ferrite,and bainitic structures.The bottom region exhibited superior mechanical properties compared with the top region.The improved strength at the bottom region can be ascribed to the formation of a high density of dislocations and finer grains.
基金supported by National Natural Science Foundation of China(Grant No.52105319)The authors are grateful to the Analysis&Testing Center and the Micro-and Nanotechnology Center at the Beijing Institute of Technology for performing the XRM experiments.
文摘Conventional cast Al-Ce alloys are challenged by the increasing demand for improved mechanical properties.To address this issue,in this study,wire-arc directed energy deposition(WA-DED)is employed for the fabrication of Al-15Ce-3Mg(wt%)alloy components.We aimed to tune the microstructure and mechanical properties via the inherent sub-rapid-solidification effect of WA-DED.In addition to significant microstructure refinement,a decrease in arc heat input leads to a larger cooling rate,up to 346℃/s,and triggers the transition from hyper-eutectic to near-eutecticα-Al/Al_(11)Ce_(3)microstructures with the suppression of primary Al_(11)Ce_(3)intermetallics.Such microstructural modification improves the mechanical properties,resulting in higher yield and ultimate tensile strengths than those of the as-cast counterpart alloy.The fracture process involves the formation of dim-ples around Al_(11)Ce_(3),cracking of large Al_(11)Ce_(3) particles,and growth,merging,and fracture of pores.The strength increment is mainly contributed by particle-size strengthening mediated by microstructure refinement as well as the targeted formation of near-eutecticα-Al/Al_(11)Ce_(3)microstructures.
基金sponsored by the National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact 2021ZX52002222019the Natural Science Foundation of China(NSFC No.U2141216)the Chongqing Technology Innovation and Application Special Program.
文摘This study investigated the effect of thermal cycles on Cu-modified Ti64 thin-walled components deposited using the wire-arc directed energy deposition(wire-arc DED)process.For the samples before and after experiencing thermal cycles,it was found that both microstructures consisted of priorβ,grain boundaryα(GBα),and basketweave structures containingα+βlamellae.Thermal cycles realized the refinement ofαlaths,the coarsening of priorβgrains andβlaths,while the size and morphology of continuously distributed GBαremained unchanged.The residualβcontent was increased after thermal cycles.Compared with the heat-treated sample with nanoscale Ti2Cu formed,short residence time in high temperature caused by the rapid cooling rate of thermal cycles restricted Ti2Cu formation.No formation of brittle Ti2Cu means that only grain refinement strengthening and solid-solution strengthening matter.The yield strength increased from 809.9 to 910.85 MPa(12.46%increase).Among them,the main contribution from solid solution strengthening(~51 MPa)was due to the elemental redistribution effect betweenαandβphases caused by thermal cycles through quantitative analysis.The ultimate tensile strength increased from 918.5 to 974.22 MPa(6.1%increase),while fracture elongation increased from 6.78 to 10.66%(57.23%increase).Grain refinement ofαlaths,the promotedα′martensite decomposition,decreased aspect ratio,decreased Schmid factor,and local misorientation change ofαlaths are the main factors in improved ductility.Additionally,although the fracture modes of the samples in the top and middle regions are both brittle-ductile mixed fracture mode,the thermal cycles still contributed to an improvement in tensile ductility.
基金Project(ZZYJKT2024-08)supported by the State Key Laboratory of Precision Manufacturing for Extreme Service Performance,ChinaProject(2022JB11GX004)supported by Selection of the best Candidates to Undertake Key Research Projects by Dalian City,ChinaProject(201806835007)supported by China Scholarship Council。
文摘Wire-arc additive manufacture(WAAM)has great potential for manufacturing of Al-Cu components.However,inferior mechanical properties of WAAM deposited material restrict its industrial application.Inter-layer cold rolling and thermo-mechanical heat treatment(T8)with pre-stretching deformation between solution and aging treatment were adopted in this study.Their effects on hardness,mechanical properties and microstructure were analyzed and compared to the conventional heat treatment(T6).The results show that cold rolling increases the hardness and strengths,which further increase with T8 treatment.The ultimate tensile strength(UTS)of 513 MPa and yield stress(YS)of 413 MPa can be obtained in the inter-layer cold-rolled sample with T8 treatment,which is much higher than that in the as-deposited samples.The cold-rolled samples show higher elongation than that of as-deposited ones due to significant elimination of porosity in cold rolling;while both the T6 and T8 treatments decrease the elongation.The cold rolling and pre-stretching deformation both contribute to the formation of dense and dispersive precipitatedθ′phases,which inhibits the dislocation movement and enhances the strengths;as a result,T8 treatment shows better strengthening effect than the T6 treatment.The strengthening mechanism was analyzed and it was mainly related to work hardening and precipitation strengthening.
基金supported by National Natural Science Foundation of China(Grant Nos.52305331,U20B2031)China Postdoctoral Science Foundation(Grant No.2022M710298)Fundamental Research Funds for the Central Universities,China(Grant No.YWF-22-L-607).
文摘Wire-arc directed energy deposition(WA-DED)has emerged as a transformative technology for producing large-scale metal components owing to its capacity for cost-effective fabrication and suitable deposition rates.Recently,the focus has shifted to the WA-DED of magnesium alloys,which are promising lightweight structural materials in the aerospace transportation and military industries.This article systematically reviews recent advancements in magnesium alloys fabricated using WA-DED.It discusses aspects such as forming quality,internal defects,microstructural evolution,and mechanical properties.Prevalent internal defects such as pores and cracks in WA-DED magnesium alloys are identified and characterized.Additionally,strategies for enhancing the manufacturing quality are elucidated.Furthermore,this article comprehensively explores the underlying mechanisms of the interplay among process parameters,internal defects,and microstructural heterogeneity.The main objective is to provide insights into and strategies for defect elimination,microstructural homogenization,and property enhancement.Finally,some perspectives are proposed for further progress in the application of WA-DED magnesium alloy components for superior performance.
