Low-density short-duration pulsed current-assisted aging treatment was applied to the Ti-6Al-4V-0.5Mo-0.5Zr alloy subjected to different solution treatments.The results show that numerous α_(p) phases redissolve into...Low-density short-duration pulsed current-assisted aging treatment was applied to the Ti-6Al-4V-0.5Mo-0.5Zr alloy subjected to different solution treatments.The results show that numerous α_(p) phases redissolve into the new β phase during the pulsed current-assisted aging process,and then the newly formed β phase is mainly transformed into the β_(t) phase,with occasional transition to new α_(p) phase,leading to a remarkable grain refinement,especially for the lamellarαs phases.In comparison to conventional aging treatment,the pulsed current-assisted aging approach achieves a significant enhancement in strength without degrading ductility,yielding an excellent mechanical property combination:a yield strength of 932 MPa,a tensile strength of 1042 MPa,and an elongation of 12.2%.It is primarily ascribed to the increased fraction of β_(t) phases,the obvious grain refinement effect,and the slip block effect induced by the multiple-variantαs colonies distributed within β_(t) phases.展开更多
Synergistically and simultaneously enhancing strength and ductility has been a major challenge for the development and applications of titanium matrix composites.Herein,a new design methodology for Ti_(2)Cu/Ti_(6)Al4V...Synergistically and simultaneously enhancing strength and ductility has been a major challenge for the development and applications of titanium matrix composites.Herein,a new design methodology for Ti_(2)Cu/Ti_(6)Al4V composites with superior strength and ductility is reported.展开更多
Lightweight high/medium-entropy alloys(H/MEAs)possess attractive properties such as high strength-to-weight ratios,however,their limited room-temperature tensile ductility hinders their widespread engi-neering impleme...Lightweight high/medium-entropy alloys(H/MEAs)possess attractive properties such as high strength-to-weight ratios,however,their limited room-temperature tensile ductility hinders their widespread engi-neering implementation,for instance in aerospace structural components.This work achieved a transfor-mative improvement of room-temperature tensile ductility in Ti-V-Zr-Nb MEAs with densities of 5.4-6.5 g/cm3,via ingenious composition modulation.Through the systematic co-adjustment of Ti and V contents,an intrinsic ductility mechanism was unveiled,manifested by a transition from predominant intergranular brittle fracture to pervasive ductile dimpled rupture.Notably,the modulated deformation mechanisms evolved from solitary slip toward collaborative multiple slip modes,without significantly compromising strength.Compared to equimolar Ti-V-Zr-Nb,a(Ti1.5V)3ZrNb composition demonstrated an impressive 360%improvement in elongation while sustaining a high yield strength of around 800 MPa.Increasing Ti and V not only purified the grain boundaries by reducing detrimental phases,but also tai-lored the deformation dislocation configurations.These insights expanded the applicability of lightweight HEAs to areas demanding combined high strength and ductility.展开更多
1.Introduction.Cold Spray(CS)is a highly advanced solid-state metal depo-sition process that was first developed in the 1980s.This innovative technique involves the high-speed(300-1200 m/s)impact deposition of micron-...1.Introduction.Cold Spray(CS)is a highly advanced solid-state metal depo-sition process that was first developed in the 1980s.This innovative technique involves the high-speed(300-1200 m/s)impact deposition of micron-sized particles(5-50μm)to fabricate coatings[1-3].CS has been extensively used in a variety of coating applications,such as aerospace,automotive,energy,medical,marine,and others,to provide protection against high temperatures,corrosion,erosion,oxidation,and chemicals[4,5].Nowadays,the technical interest in CS is twofold:(i)as a repair process for damaged components,and(ii)as a solid-state additive manufacturing process.Compared to other fusion-based additive manufacturing(AM)technologies,Cold Spray Additive Manufacturing(CSAM)is a new member of the AM family that can enable the fabrication of deposits without undergoing melting.The chemical composition has been largely preserved from the powder to the deposit due to the minimal oxidation.The significant advantages of CSAM over other additive manufacturing processes include a high production rate,unlimited deposition size,high flexibility,and suitability for repairing damaged parts.展开更多
Traditional metals often exhibit a trade-offbetween strength and plasticity,limiting their wide application of metals in aerospace,transportation,energy industry and other fields[1-3].In order to overcome this dilemma...Traditional metals often exhibit a trade-offbetween strength and plasticity,limiting their wide application of metals in aerospace,transportation,energy industry and other fields[1-3].In order to overcome this dilemma,high-entropy alloys(HEAs),proposed by Yeh et al.and Cantor et al.,are currently of great interest in the materials community due to their excellent mechanical properties[4-7].To further promote the wide application of HEAs in industrial production,Lu et al.developed a new eutectic high-entropy alloy(EHEAs)by combining the potential advantages of traditional eutectic alloys and HEAs[8-11].展开更多
The growing demand for material properties in challenging environments has led to a surge of interest in rapid composition design. Given the great potential composition space, the field of high/medium entropy alloys (...The growing demand for material properties in challenging environments has led to a surge of interest in rapid composition design. Given the great potential composition space, the field of high/medium entropy alloys (H/MEAs) still lacks effective atomic-scale composition design and screening schemes, which hinders the accurate prediction of desired composition and properties. This study proposes a novel approach for rapidly designing the composition of materials with the aim of overcoming the trade-off between strength and ductility in metal matrix composites. The effect of chemical composition on stacking fault energy (SFE), shear modulus, and phase stability was investigated through the use of molecular dynamics (MD) and thermodynamic calculation software. The alloy's low SFE, highest shear modulus, and stable face-centered cubic (FCC) phase have been identified as three standard physical quantities for rapid screening to characterize the deformation mechanism, ultimate tensile strength, phase stability, and ductility of the alloy. The calculation results indicate that the optimal composition space is expected to fall within the ranges of 17 %–34 % Ni, 33 %–50 % Co, and 25 %–33 % Mn. The comparison of stress-strain curves for various predicted components using simulated and experimental results serves to reinforce the efficacy of the method. This indicates that the screening criteria offer a necessary design concept, deviating from traditional strategies and providing crucial guidance for the rapid development and application of MEAs.展开更多
A newly developed P-doped CrCoNi medium-entropy alloy(MEA)provides both higher yield strength and larger uniform elongation than the conventional CrCoNi MEA,even superior tensile ductility to the other-element-doped C...A newly developed P-doped CrCoNi medium-entropy alloy(MEA)provides both higher yield strength and larger uniform elongation than the conventional CrCoNi MEA,even superior tensile ductility to the other-element-doped CrCoNi MEAs at similar yield strength levels.P segregation at grain boundaries(GBs)and dissolution inside grain interiors,together with the related lower stacking fault energy(SFE)are found in the P-doped CrCoNi MEA.Higher hetero-deformation-induced(HDI)hardening rate is observed in the P-doped CrCoNi MEA due to the grain-to-grain plastic deformation and the dynamic structural refinement by high-density stacking fault-walls(SFWs).The enhanced yield strength in the P-doped CoCrNi MEA can be attributed to the strong substitutional solid-solution strengthening by severer lattice distortion and the GB strengthening by phosphorus segregation at GBs.During the tensile deformation,the multiple SFW frames inundated with massive multi-orientational tiny planar stacking faults(SFs)between them,rather than deformation twins,are observed to induce dynamic structural refinement for forming par-allelepiped domains in the P-doped CoCrNi MEA,due to the lower SFE and even lower atomically-local SFE.These nano-sized domains with domain boundary spacing at tens of nanometers can block disloca-tion movement for strengthening on one hand,and can accumulate defects in the interiors of domains for exceptionally high hardening rate on the other hand.展开更多
The development of cost-effective titanium alloys with outstanding mechanical properties has always been a primary concern of the modern aerospace industry.However,the intrinsic sensitivity of theirαprecipitates to h...The development of cost-effective titanium alloys with outstanding mechanical properties has always been a primary concern of the modern aerospace industry.However,the intrinsic sensitivity of theirαprecipitates to heat treatments proliferates the manufacturing costs to achieve desirable strength and ductility,especially in engineering occasions.In current work,a silicide-containingα+βTi-5Al-7.5V-0.5Mo-0.5Zr-0.5Si(TC5751S)alloy has been evidenced to exhibit advanced mechanical properties with reduced sensitivity to heat treatments.It is noted that more nano-scale secondaryα(αs)precipitate with a simultaneous dissolution in micron-scale primaryα(αp)and(Ti,Zr)_(5)Si_(3)silicides in the current alloy as the solution temperature increases.However,this alloy shows excellent and stabilized strength-ductility synergy in all cases(ultimate tensile strength:1335±30 MPa,yield strength:1245±30 MPa,fracture strain:9.6%±0.5%)irrespective of the aforementioned variations in the microstructure.This stabilized strength and ductility of TC5751S are rationalized based on the compensation mechanisms be-tween the contributions from silicide and heterogeneousαprecipitates.The quantitative analysis unveils that the increased α_(s)/β phase boundary strengthening(σ_(PB))is approximately offset by the decrease in silicide strengthening(σ_(silicide))due to silicide dissolution with increasing solution temperatures,leading to the strength of TC5751S in a dynamic equilibrium state.Simultaneously,the dissolution of silicides re-duces the cracking tendency and complements the ductility loss due to α_(p) reduction and α_(s) precipitation,leading to the ductility insensitive to heat treatments.Therefore,the compensating role of silicides to the effects of heterogeneousαprecipitates on both the strength and ductility of titanium alloys has been well-verified in our work,providing a novel pathway to the development of high-performance titanium alloys friendly to processing strategies.展开更多
The large surface area of dealloyed nanoporous metals has enabled novel functional properties includ-ing catalysis,energy conversion and storage,actuation and sensing.Nevertheless,the practical applica-tion of these m...The large surface area of dealloyed nanoporous metals has enabled novel functional properties includ-ing catalysis,energy conversion and storage,actuation and sensing.Nevertheless,the practical applica-tion of these materials is hindered by their extreme brittleness under tension and bending.Filling the nanopores with polymer may enhance their ductility;however,it eliminates the large open surface area and thereby leads to the loss of the aforementioned functionalities.In this study,we fabricated a hierar-chical nanoporous Cu with micron-scale pores at the higher hierarchical level and nanoscale pores at the lower level.By infiltrating the large pores with epoxy,we obtained a material that combines excellent mechanical stability with surface-enabled functionalities.In this material,the soft and ductile epoxy net-work suppresses crack propagation during deformation,enhancing the fracture strain from nearly zero to 46%under tension.Meanwhile,the nanoporous structure remains open and offers a large surface area that is crucial for functionalities.For example,the electrochemical actuation behavior of a hierarchical nanoporous Cu dose not change significantly when its large pore channels are infiltrated with epoxy.This study presents a strategy to overcome the brittleness of dealloyed nanoporous materials while retaining the large surface area,thus paving the way for the practical applications of this new type of functional materials.展开更多
Grain boundary hardening is an important mechanism for improving the strength and ductility of metal materials.However,the industrial fabrication of fine-grained FeCrAl alloys was limited by the interaction between th...Grain boundary hardening is an important mechanism for improving the strength and ductility of metal materials.However,the industrial fabrication of fine-grained FeCrAl alloys was limited by the interaction between the recrystallization and precipitation.Here,we report the facile mass production of fine-grained FeCrAl alloys by Si alloying and manipulation of the recrystallization process through introducing heterogeneous Si-rich Laves precipitates.The pre-precipitation of heterogeneous Laves phase not only promotes subsequent recrystallization grain nucleation by the PSN(Particles simultaneous nucleation)and SIBM(Strain-induced grain boundary migration)mechanisms,but also provides resistance to grain growth by the Zener pinning mechanism.Moreover,continuous grain refinement can be achieved by intensifying the heterogeneous Laves precipitates through decreasing their formation energy.This approach enables the preparation of a fully recrystallized fine-grain structure with a grain size of 4.6μm without the introduction of segregated boundaries.Consequently,an unprecedented synergy enhancement of strength(σ_(y)=625 MPa,σ_(uts)=867 MPa,)and ductility(ε_(u)=13.8%)is achieved in the fine-grain structured FeCrAl alloys compared with the coarse grain counterpart.The experimental results prove that the proposed strategy is appropriate for developing high strength and ductility FeCrAl alloys,and further boosting its potential applications as accident-tolerant-fuel cladding in nuclear reactors.In addition,this grainrefinement strategy should be extendable to other alloy systems,where there is a significant difference between precipitation and recrystallization temperatures.展开更多
In this research,a high ductility Mg-Gd-Mn magnesium alloy was designed and developed,with an elongation capability surpassing 50%.To gain insights into the underlying mechanism behind the high ductility of the Mg-2Gd...In this research,a high ductility Mg-Gd-Mn magnesium alloy was designed and developed,with an elongation capability surpassing 50%.To gain insights into the underlying mechanism behind the high ductility of the Mg-2Gd-0.5Mn alloy,quasi-in-situ electron backscattered diffraction and two-beam diffraction were conducted.The results reveal that the Mg-Gd-Mn alloy exhibits a distinct rare-earth texture,and the activation of non-basal slip systems is evident from the clear observation of non-basal slip traces during the later stages of deformation.However,the primary deformation mechanisms in Mg-Gd-Mn alloy remain basalslip and{10–12}tensile twinning,and the remarkable ductility observed in Mg-Gd-Mn alloys can be attributed to the softening of non-basal slip modes,which leads to a coordinated deformation between various modes of deformation.To further validate this conclusion,an analysis was conducted using a visco-plastic self-consistent(VPSC)model to investigate the relative activity of basal and non-basal slip in Mg-Gd-Mn alloys.The obtained results align well with experimental observations,providing additional support for the hypothesis.展开更多
Metastable β titanium alloy is an ideal material for lightweight and high strength due to its excellent comprehensive mechanical properties.However,overcoming the trade-off relation between strength and ductility rem...Metastable β titanium alloy is an ideal material for lightweight and high strength due to its excellent comprehensive mechanical properties.However,overcoming the trade-off relation between strength and ductility remains a significant challenge.In this study,the mechanical properties of Ti-38644 alloy were optimized by introducing a heterogeneous bi-grain bi-lamella(BG-BL)structure through a well-designed combination of rolling,drawing and heat treatment.The results demonstrate that the present BG-BL Ti-38644 alloy shows a tensile strength of~1500 MPa and a total elongation of 18%.In particular,the high strength-elongation combination of the BG-BL Ti-38644 alloy breakthroughs the trade-off relation in all the titanium alloys available.The recrystallized grains with low dislocation enhance the ductility of the Ti-38644 alloy,while the highly distorted elongated grains mainly contribute to the high strength.The present study provides a new principle for designing Ti alloys with superior strength and ductility.展开更多
Composition design is one of the signifcant methods to break the trade-of relation between strength and ductility of medium-/high-entropy alloys(M/HEAs).Herein,we introduced three fundamental principles for the compos...Composition design is one of the signifcant methods to break the trade-of relation between strength and ductility of medium-/high-entropy alloys(M/HEAs).Herein,we introduced three fundamental principles for the composition design:high elastic modulus,low stacking-fault energy(SFE),and appropriate phase stability.Subsequently,based on the three principles of component design and the frst-principles calculation results,we designed and investigated a non-equiatomic Ni28 MEA with a single-phase and uniform microstructure.The Ni28 MEA has great mechanical properties with yield strength of 329.5 MPa,tensile strength of 829.4 MPa,and uniform elongation of 56.9%at ambient temperature,respectively.The high ductility of Ni28 MEA may be attributed to the dynamically refned microstructure composed of hexagonal close-packed(HCP)lamellas and stacking faults(SFs),which provide extremely high work-hardening ability.This work demonstrates the feasibility of the three principles for composition design and can be extended to more M/HEAs in the future.展开更多
The role of cerium(Ce)in enhancing the hot ductility of super austenitic stainless steel S32654 at 850–1250℃was systematically unveiled through theoretical calculations and microstructure characterization.The result...The role of cerium(Ce)in enhancing the hot ductility of super austenitic stainless steel S32654 at 850–1250℃was systematically unveiled through theoretical calculations and microstructure characterization.The results indicated that Ce microalloying improved the hot ductility of S32654 throughout the entire deformation temperature range.Specifically,the addition of Ce greatly enhanced the hot ductility in the low(850–900℃)and high(1100–1250℃)temperature ranges,but only slightly increased that in the medium temperature range(900–1100℃).At 850–900℃,Ce addition not only reduced the sulfur(S)content and suppressed the S segregation at the grain boundary,but also promoted the formation of slip bands and deformation twins,apparently improving the hot ductility.At 900–1100℃,Ce addition promoted the nucleation of intergranularσphases and dynamic recrystallization(DRX)grains,which have adverse and beneficial effects on the hot ductility,respectively.As the temperature increased,the precipitation tendency presented a first increasing and then decreasing trend around 1000℃,while the DRX gradually increased.Accordingly,the improvement degree of Ce on the hot ductility first weakened and then enhanced.At 1100–1250℃,Ce significantly promoted the DRX to form more fine and uniform deformation structure,thereby remarkably increasing the cracking resistance and then the hot ductility.展开更多
1.Introduction Titanium(Ti)and its alloy have become a critical structural material in aerospace,weaponry,and equipment industries due to their high strength,low density,and excellent corrosion resistance[1-3].
Strain rate is a critical factor influencing the mechanical response of hexagonal close-packed titanium under cryogenic conditions.In this study,uniaxial tensile tests were performed on commercially pure titanium at 7...Strain rate is a critical factor influencing the mechanical response of hexagonal close-packed titanium under cryogenic conditions.In this study,uniaxial tensile tests were performed on commercially pure titanium at 77 K over a broad strain rate range from 0.001 to 1 s^(-1).A critical strain rate of approximately 0.5 s^(-1)was identified,above which ductility exhibits a pronounced reduction,whereas below this threshold,ductility remains relatively stable.Through comprehensive analyses of strain evolution,deformed microstructure,and fracture morphology,this behavior is attributed to severe localized adiabatic heating resulting from inhomogeneous deformation,rather than conventional twin or shear mechanisms.展开更多
This study deals with the development of a 780-MPa-class hot-rolled advanced high-strength steel(AHSS)with an ultrahigh elongation at break of approximately 30%and strength-ductility product exceeding 24 GPa·%,in...This study deals with the development of a 780-MPa-class hot-rolled advanced high-strength steel(AHSS)with an ultrahigh elongation at break of approximately 30%and strength-ductility product exceeding 24 GPa·%,indicating the excellent formability of the newly developed AHSS.The microstructure of the newly developed 780-MPa-class AHSS consists mainly of the triplex phase of ferrite,bainite,and retained austenite with a volume fraction of 10%±2%.The stability of the retained austenite in the newly developed AHSS is much higher than that of conventional transformation-induced plasticity steels,in which the retained austenite is prone to transformation into martensite under deformation.At a pre-strain lower than 1.2%,the volume fraction of the retained austenite and the elongation at break of the present 780-MPa-class AHSS remain almost unchanged,showing a high tolerance in the process window during leveling or straightening.Therefore,the present 780-MPa-class AHSS is particularly suitable for the production of components with complex shapes.展开更多
High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicle...High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicles enhances structural reliability and cost efficiency.However,HPDC Mg alloys face challenges related to casting defects such as porosity,cold shuts,and oxides.These defects influence tensile strength and ductility,depending on their location and size.This study employs finite element(FE)modeling to investigate how a dominant large pore,its position,and the sample size affect the ductility of thin-walled HPDC Mg.Motivated by the ductility variations reported in literature and the experimental findings on AM60 castings,synthetic microstructure-based models are used to assess the effects of different pore sizes and locations.The results indicate the presence of three different regions based on the large pore size and model size:1)a region dominated by the effects of the large pore,2)a plateau region dominated by pore interactions,and 3)a transient region between these two effects.A threshold distance from the sample edge (d≈0.9√D·L)is proposed,within which a large pore can significantly reduce ductility.Additionally,large pores near edges contribute to ductility variations in Mg castings.展开更多
High temperature tensile were performed by using a thermo-mechanical GW1600 to simulate the deformation of Ti microalloy steels at high temperatures and low deformation rates similar to those during continuous casting...High temperature tensile were performed by using a thermo-mechanical GW1600 to simulate the deformation of Ti microalloy steels at high temperatures and low deformation rates similar to those during continuous casting.An equivalent austenite diameter was proposed,taking into account the weakening effects of proeutectoid ferrite films and Ti carbonitride precipitation.Based on this,a hot ductility prediction model for the slab was established to investigated hot ductility.The results show that as Ti content increases,the hot ductility of Ti microalloy steel initially increases and then decreases.At low Ti content,the pinning effect of Ti carbonitrides increases with the increase in Ti content,which inhibits grain coarsening for improving hot ductility.As Ti content increases,the size of carbonitrides grows,weakening the pinning effect and leading to austenite grain coarsening.Simultaneously,the formation of Ti carbonitrides inhibits proeutectoid ferrite film formation,leading to a reduction in its thickness.These combined factors reduce the hot ductility of the continuous casting steel.According to the hot ductility prediction model,in order of severity,the factors affecting hot ductility are:proeutectoid ferrite film,chain-like nanoscale Ti carbonitrides,austenite grain size,and dispersed nanoscale Ti carbonitrides.An accuracy error of less than 10%is shown by the model.展开更多
Austenitic stainless steels(ASSs)are widely used in various in-dustries such as aerospace,nuclear energy,food,and biotechnol-ogy owing to their exceptional combination of corrosion resistance,weldability,toughness,and...Austenitic stainless steels(ASSs)are widely used in various in-dustries such as aerospace,nuclear energy,food,and biotechnol-ogy owing to their exceptional combination of corrosion resistance,weldability,toughness,and formability[1,2].However,a signifi-cant drawback of ASSs is their low yield strength,which limits their applications in extreme environments[3].Grain boundary(GB)engineering plays a crucial role in enhancing the strength of ASSs[4,5].For instance,grain refinement techniques such as cold rolling followed by annealing[6],severe plastic deformation(SPD)[7],and surface mechanical attrition/rolling treatments[8,9]introduce high-angle GBs(HAGBs)into ASSs,thereby improving their strength.However,the high density of HAGBs limits their ca-pacity for dislocation storage and multiplication,leading to a sig-nificant loss of ductility[10,11].Additionally,several studies have shown that twin boundaries(TBs)can simultaneously enhance the strength,toughness,and corrosion resistance of ASSs[12,13].展开更多
基金National Key Research and Development Program of China(2021YFB3700801)。
文摘Low-density short-duration pulsed current-assisted aging treatment was applied to the Ti-6Al-4V-0.5Mo-0.5Zr alloy subjected to different solution treatments.The results show that numerous α_(p) phases redissolve into the new β phase during the pulsed current-assisted aging process,and then the newly formed β phase is mainly transformed into the β_(t) phase,with occasional transition to new α_(p) phase,leading to a remarkable grain refinement,especially for the lamellarαs phases.In comparison to conventional aging treatment,the pulsed current-assisted aging approach achieves a significant enhancement in strength without degrading ductility,yielding an excellent mechanical property combination:a yield strength of 932 MPa,a tensile strength of 1042 MPa,and an elongation of 12.2%.It is primarily ascribed to the increased fraction of β_(t) phases,the obvious grain refinement effect,and the slip block effect induced by the multiple-variantαs colonies distributed within β_(t) phases.
基金supported by the National Natural Science Foundation of China(NSFC,No.52271138)the Key Research and Development Projects of Shaanxi Province(Nos.2023-YBGY-433 and 2024GX-YBXM-356)+1 种基金Xi'an Talent Program Young Innovative Talents(No.XAYC 2023030)the Science and Technology Development Plan Project of Shaanxi Province(No.S2024-JC-QN-2642).
文摘Synergistically and simultaneously enhancing strength and ductility has been a major challenge for the development and applications of titanium matrix composites.Herein,a new design methodology for Ti_(2)Cu/Ti_(6)Al4V composites with superior strength and ductility is reported.
基金supported by the National Natural Science Foundation of China(Nos.51925103,52271149,52171159)the Innovation Program of Shanghai Municipal Education Commission(No.2021-01-07-00-09-E00114)+5 种基金the Natural Science Foundation of Shanghai(22ZR1422500)the Innovation Program of Shanghai Science and Technology(No.23520760700)the Aviation Foundation(No.2023Z0530S6004)the Fund of the State Key Laboratory of Solidification Processing in NWPU(No.SKLSP202221)the financial support from Program 173(No.2020-JCIQ-ZD-186-01)the Space Utilization System of China Manned Space Engineering(No.KJZ-YY-NCL08).
文摘Lightweight high/medium-entropy alloys(H/MEAs)possess attractive properties such as high strength-to-weight ratios,however,their limited room-temperature tensile ductility hinders their widespread engi-neering implementation,for instance in aerospace structural components.This work achieved a transfor-mative improvement of room-temperature tensile ductility in Ti-V-Zr-Nb MEAs with densities of 5.4-6.5 g/cm3,via ingenious composition modulation.Through the systematic co-adjustment of Ti and V contents,an intrinsic ductility mechanism was unveiled,manifested by a transition from predominant intergranular brittle fracture to pervasive ductile dimpled rupture.Notably,the modulated deformation mechanisms evolved from solitary slip toward collaborative multiple slip modes,without significantly compromising strength.Compared to equimolar Ti-V-Zr-Nb,a(Ti1.5V)3ZrNb composition demonstrated an impressive 360%improvement in elongation while sustaining a high yield strength of around 800 MPa.Increasing Ti and V not only purified the grain boundaries by reducing detrimental phases,but also tai-lored the deformation dislocation configurations.These insights expanded the applicability of lightweight HEAs to areas demanding combined high strength and ductility.
基金supported by the National Natural Science Foundation of China(No.52061135101 and 52001078)the German Research Foundation(DFG,No.448318292)+3 种基金the Technology Innovation Guidance Special Foundation of Shaanxi Province(No.2023GXLH-085)the Fundamental Research Funds for the Central Universities(No.D5000240161)the Project of Key areas of innovation team in Shaanxi Province(No.2024RS-CXTD-20)The author Yingchun Xie thanks the support from the National Key R&D Program(No.2023YFE0108000).
文摘1.Introduction.Cold Spray(CS)is a highly advanced solid-state metal depo-sition process that was first developed in the 1980s.This innovative technique involves the high-speed(300-1200 m/s)impact deposition of micron-sized particles(5-50μm)to fabricate coatings[1-3].CS has been extensively used in a variety of coating applications,such as aerospace,automotive,energy,medical,marine,and others,to provide protection against high temperatures,corrosion,erosion,oxidation,and chemicals[4,5].Nowadays,the technical interest in CS is twofold:(i)as a repair process for damaged components,and(ii)as a solid-state additive manufacturing process.Compared to other fusion-based additive manufacturing(AM)technologies,Cold Spray Additive Manufacturing(CSAM)is a new member of the AM family that can enable the fabrication of deposits without undergoing melting.The chemical composition has been largely preserved from the powder to the deposit due to the minimal oxidation.The significant advantages of CSAM over other additive manufacturing processes include a high production rate,unlimited deposition size,high flexibility,and suitability for repairing damaged parts.
基金financial supported by the Natural Science Foundation of Jiangsu Provincial Education Department(No.24KJB430003)the Natural Science Foundation for Young Scholars of Jiangsu Province(No.BK20240979)+3 种基金support of Natural Science Foundation for Young Scholars of Jiangsu Province(No.BK20220628)the National Natural Science Foundation for Young Scholars of China(52301130)the Changzhou Sci&Tech program(No.GJ20220153)support of the Natural Science Foundation of Jiangsu Provincial Education Department(No.21KJB430001).
文摘Traditional metals often exhibit a trade-offbetween strength and plasticity,limiting their wide application of metals in aerospace,transportation,energy industry and other fields[1-3].In order to overcome this dilemma,high-entropy alloys(HEAs),proposed by Yeh et al.and Cantor et al.,are currently of great interest in the materials community due to their excellent mechanical properties[4-7].To further promote the wide application of HEAs in industrial production,Lu et al.developed a new eutectic high-entropy alloy(EHEAs)by combining the potential advantages of traditional eutectic alloys and HEAs[8-11].
基金funding from the National Natural Science Foundation of China(Nos.52063017 and 52061025)the Major Science and Technology Project of Gansu Province(Nos.22ZD6GA008 and 20ZD7GJ008)+3 种基金the Natural Science Foundation of Gansu Province(No.23JRRA820)The Science and Technology Project of Major Science and Technology Project of Gansu Province(No.22ZD6GA008)the Science and Technology Project of Gansu Province(No.23YFGA0058)the College Industry Support Plan of Gansu Province(No.2023CYZC-27).
文摘The growing demand for material properties in challenging environments has led to a surge of interest in rapid composition design. Given the great potential composition space, the field of high/medium entropy alloys (H/MEAs) still lacks effective atomic-scale composition design and screening schemes, which hinders the accurate prediction of desired composition and properties. This study proposes a novel approach for rapidly designing the composition of materials with the aim of overcoming the trade-off between strength and ductility in metal matrix composites. The effect of chemical composition on stacking fault energy (SFE), shear modulus, and phase stability was investigated through the use of molecular dynamics (MD) and thermodynamic calculation software. The alloy's low SFE, highest shear modulus, and stable face-centered cubic (FCC) phase have been identified as three standard physical quantities for rapid screening to characterize the deformation mechanism, ultimate tensile strength, phase stability, and ductility of the alloy. The calculation results indicate that the optimal composition space is expected to fall within the ranges of 17 %–34 % Ni, 33 %–50 % Co, and 25 %–33 % Mn. The comparison of stress-strain curves for various predicted components using simulated and experimental results serves to reinforce the efficacy of the method. This indicates that the screening criteria offer a necessary design concept, deviating from traditional strategies and providing crucial guidance for the rapid development and application of MEAs.
基金supported by the National Key R&D Program of China(No.2019YFA0209902)the Natural Science Foundation of China(Nos.52071326,52192593,51601204)+1 种基金the NSFC Basic Science Center Program for Multiscale Problems in Nonlinear Mechanics(No.11988102)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB22040503).
文摘A newly developed P-doped CrCoNi medium-entropy alloy(MEA)provides both higher yield strength and larger uniform elongation than the conventional CrCoNi MEA,even superior tensile ductility to the other-element-doped CrCoNi MEAs at similar yield strength levels.P segregation at grain boundaries(GBs)and dissolution inside grain interiors,together with the related lower stacking fault energy(SFE)are found in the P-doped CrCoNi MEA.Higher hetero-deformation-induced(HDI)hardening rate is observed in the P-doped CrCoNi MEA due to the grain-to-grain plastic deformation and the dynamic structural refinement by high-density stacking fault-walls(SFWs).The enhanced yield strength in the P-doped CoCrNi MEA can be attributed to the strong substitutional solid-solution strengthening by severer lattice distortion and the GB strengthening by phosphorus segregation at GBs.During the tensile deformation,the multiple SFW frames inundated with massive multi-orientational tiny planar stacking faults(SFs)between them,rather than deformation twins,are observed to induce dynamic structural refinement for forming par-allelepiped domains in the P-doped CoCrNi MEA,due to the lower SFE and even lower atomically-local SFE.These nano-sized domains with domain boundary spacing at tens of nanometers can block disloca-tion movement for strengthening on one hand,and can accumulate defects in the interiors of domains for exceptionally high hardening rate on the other hand.
基金supported by the National Key Research and Development Program of China(No.2021YFB3702604)the National Natural Science Foundation of China(No.52001258).
文摘The development of cost-effective titanium alloys with outstanding mechanical properties has always been a primary concern of the modern aerospace industry.However,the intrinsic sensitivity of theirαprecipitates to heat treatments proliferates the manufacturing costs to achieve desirable strength and ductility,especially in engineering occasions.In current work,a silicide-containingα+βTi-5Al-7.5V-0.5Mo-0.5Zr-0.5Si(TC5751S)alloy has been evidenced to exhibit advanced mechanical properties with reduced sensitivity to heat treatments.It is noted that more nano-scale secondaryα(αs)precipitate with a simultaneous dissolution in micron-scale primaryα(αp)and(Ti,Zr)_(5)Si_(3)silicides in the current alloy as the solution temperature increases.However,this alloy shows excellent and stabilized strength-ductility synergy in all cases(ultimate tensile strength:1335±30 MPa,yield strength:1245±30 MPa,fracture strain:9.6%±0.5%)irrespective of the aforementioned variations in the microstructure.This stabilized strength and ductility of TC5751S are rationalized based on the compensation mechanisms be-tween the contributions from silicide and heterogeneousαprecipitates.The quantitative analysis unveils that the increased α_(s)/β phase boundary strengthening(σ_(PB))is approximately offset by the decrease in silicide strengthening(σ_(silicide))due to silicide dissolution with increasing solution temperatures,leading to the strength of TC5751S in a dynamic equilibrium state.Simultaneously,the dissolution of silicides re-duces the cracking tendency and complements the ductility loss due to α_(p) reduction and α_(s) precipitation,leading to the ductility insensitive to heat treatments.Therefore,the compensating role of silicides to the effects of heterogeneousαprecipitates on both the strength and ductility of titanium alloys has been well-verified in our work,providing a novel pathway to the development of high-performance titanium alloys friendly to processing strategies.
基金financially supported by the National Natural Science Foundation of China(No.52101204).
文摘The large surface area of dealloyed nanoporous metals has enabled novel functional properties includ-ing catalysis,energy conversion and storage,actuation and sensing.Nevertheless,the practical applica-tion of these materials is hindered by their extreme brittleness under tension and bending.Filling the nanopores with polymer may enhance their ductility;however,it eliminates the large open surface area and thereby leads to the loss of the aforementioned functionalities.In this study,we fabricated a hierar-chical nanoporous Cu with micron-scale pores at the higher hierarchical level and nanoscale pores at the lower level.By infiltrating the large pores with epoxy,we obtained a material that combines excellent mechanical stability with surface-enabled functionalities.In this material,the soft and ductile epoxy net-work suppresses crack propagation during deformation,enhancing the fracture strain from nearly zero to 46%under tension.Meanwhile,the nanoporous structure remains open and offers a large surface area that is crucial for functionalities.For example,the electrochemical actuation behavior of a hierarchical nanoporous Cu dose not change significantly when its large pore channels are infiltrated with epoxy.This study presents a strategy to overcome the brittleness of dealloyed nanoporous materials while retaining the large surface area,thus paving the way for the practical applications of this new type of functional materials.
基金supported by the National Natural Science Foun-dation of China(No.52122103)the Shaanxi Province Youth In-novation Team Project(No.22JP042)+1 种基金Shaanxi Province Innova-tion Team Project(Nos.2024RS-CXTD-58 and2023-CXTD-50)Shaanxi International Science and Technology Cooperation Base(No.2020GHJD-10).
文摘Grain boundary hardening is an important mechanism for improving the strength and ductility of metal materials.However,the industrial fabrication of fine-grained FeCrAl alloys was limited by the interaction between the recrystallization and precipitation.Here,we report the facile mass production of fine-grained FeCrAl alloys by Si alloying and manipulation of the recrystallization process through introducing heterogeneous Si-rich Laves precipitates.The pre-precipitation of heterogeneous Laves phase not only promotes subsequent recrystallization grain nucleation by the PSN(Particles simultaneous nucleation)and SIBM(Strain-induced grain boundary migration)mechanisms,but also provides resistance to grain growth by the Zener pinning mechanism.Moreover,continuous grain refinement can be achieved by intensifying the heterogeneous Laves precipitates through decreasing their formation energy.This approach enables the preparation of a fully recrystallized fine-grain structure with a grain size of 4.6μm without the introduction of segregated boundaries.Consequently,an unprecedented synergy enhancement of strength(σ_(y)=625 MPa,σ_(uts)=867 MPa,)and ductility(ε_(u)=13.8%)is achieved in the fine-grain structured FeCrAl alloys compared with the coarse grain counterpart.The experimental results prove that the proposed strategy is appropriate for developing high strength and ductility FeCrAl alloys,and further boosting its potential applications as accident-tolerant-fuel cladding in nuclear reactors.In addition,this grainrefinement strategy should be extendable to other alloy systems,where there is a significant difference between precipitation and recrystallization temperatures.
基金support from the National Science Foundation of China(No.52071037)Zhejiang province science and technology planning project(No.2022C01008).
文摘In this research,a high ductility Mg-Gd-Mn magnesium alloy was designed and developed,with an elongation capability surpassing 50%.To gain insights into the underlying mechanism behind the high ductility of the Mg-2Gd-0.5Mn alloy,quasi-in-situ electron backscattered diffraction and two-beam diffraction were conducted.The results reveal that the Mg-Gd-Mn alloy exhibits a distinct rare-earth texture,and the activation of non-basal slip systems is evident from the clear observation of non-basal slip traces during the later stages of deformation.However,the primary deformation mechanisms in Mg-Gd-Mn alloy remain basalslip and{10–12}tensile twinning,and the remarkable ductility observed in Mg-Gd-Mn alloys can be attributed to the softening of non-basal slip modes,which leads to a coordinated deformation between various modes of deformation.To further validate this conclusion,an analysis was conducted using a visco-plastic self-consistent(VPSC)model to investigate the relative activity of basal and non-basal slip in Mg-Gd-Mn alloys.The obtained results align well with experimental observations,providing additional support for the hypothesis.
基金financially supported by the National Natural Science Foundation of China(Nos.52321001,52322105,52130002,U2241245,52261135634 and 52371084)the Youth Innovation Promotion Association(CAS,No.2021192)the IMR Innovation Fund(No.2023-ZD01).
文摘Metastable β titanium alloy is an ideal material for lightweight and high strength due to its excellent comprehensive mechanical properties.However,overcoming the trade-off relation between strength and ductility remains a significant challenge.In this study,the mechanical properties of Ti-38644 alloy were optimized by introducing a heterogeneous bi-grain bi-lamella(BG-BL)structure through a well-designed combination of rolling,drawing and heat treatment.The results demonstrate that the present BG-BL Ti-38644 alloy shows a tensile strength of~1500 MPa and a total elongation of 18%.In particular,the high strength-elongation combination of the BG-BL Ti-38644 alloy breakthroughs the trade-off relation in all the titanium alloys available.The recrystallized grains with low dislocation enhance the ductility of the Ti-38644 alloy,while the highly distorted elongated grains mainly contribute to the high strength.The present study provides a new principle for designing Ti alloys with superior strength and ductility.
基金supported by the National Natural Science Foundation of China(Nos.52130002 and 52321001)the National Key Research and Development Program of China(No.2022YFB3708200)the Youth Innovation Promotion Association CAS(No.2018226).
文摘Composition design is one of the signifcant methods to break the trade-of relation between strength and ductility of medium-/high-entropy alloys(M/HEAs).Herein,we introduced three fundamental principles for the composition design:high elastic modulus,low stacking-fault energy(SFE),and appropriate phase stability.Subsequently,based on the three principles of component design and the frst-principles calculation results,we designed and investigated a non-equiatomic Ni28 MEA with a single-phase and uniform microstructure.The Ni28 MEA has great mechanical properties with yield strength of 329.5 MPa,tensile strength of 829.4 MPa,and uniform elongation of 56.9%at ambient temperature,respectively.The high ductility of Ni28 MEA may be attributed to the dynamically refned microstructure composed of hexagonal close-packed(HCP)lamellas and stacking faults(SFs),which provide extremely high work-hardening ability.This work demonstrates the feasibility of the three principles for composition design and can be extended to more M/HEAs in the future.
基金financially supported by National Natural Science Foundation of China(grant nos.52325406,52374334,and U1860204)Joint Program of Science and Technology Plans in Liaoning Province(grant nos.2023JH2/101700244 and 2023JH2/101800045)+1 种基金Fundamental Research Funds for the Central Universities(grant no.N2430002)Program of Introducing Talents of Discipline to Universities(grant no.B21001).
文摘The role of cerium(Ce)in enhancing the hot ductility of super austenitic stainless steel S32654 at 850–1250℃was systematically unveiled through theoretical calculations and microstructure characterization.The results indicated that Ce microalloying improved the hot ductility of S32654 throughout the entire deformation temperature range.Specifically,the addition of Ce greatly enhanced the hot ductility in the low(850–900℃)and high(1100–1250℃)temperature ranges,but only slightly increased that in the medium temperature range(900–1100℃).At 850–900℃,Ce addition not only reduced the sulfur(S)content and suppressed the S segregation at the grain boundary,but also promoted the formation of slip bands and deformation twins,apparently improving the hot ductility.At 900–1100℃,Ce addition promoted the nucleation of intergranularσphases and dynamic recrystallization(DRX)grains,which have adverse and beneficial effects on the hot ductility,respectively.As the temperature increased,the precipitation tendency presented a first increasing and then decreasing trend around 1000℃,while the DRX gradually increased.Accordingly,the improvement degree of Ce on the hot ductility first weakened and then enhanced.At 1100–1250℃,Ce significantly promoted the DRX to form more fine and uniform deformation structure,thereby remarkably increasing the cracking resistance and then the hot ductility.
基金supported by the National Natural Science Foundation of China(Nos.52301029 and 52274359)the Fundamental Research Funds for the Central Universities(No.06500165)+2 种基金the Guangdong Basic and Applied Basic Research Foun-dation(No.2022A1515140006)the Young Elite Scientists Sponsorship Program by CAST(No.2023QNRC001)the Beijing Young Elite Scientists Sponsorship Program by BMES。
文摘1.Introduction Titanium(Ti)and its alloy have become a critical structural material in aerospace,weaponry,and equipment industries due to their high strength,low density,and excellent corrosion resistance[1-3].
基金financially supported by the National Key Research&Development Plan(No.2022YFE0110600)the National Natural Science Foundation of China(Nos.52171117,52371113,92263201 and 52175306)+3 种基金Qing Lan Project(No.54944004)the Basic Research Program of Jiangsu(Nos.BK20232011 and BK20232025)the Postdoctoral Fellowship Program of CPSF(No.GZC20233481)Tuoyuan project of Nanjing Tech University(No.20230113)
文摘Strain rate is a critical factor influencing the mechanical response of hexagonal close-packed titanium under cryogenic conditions.In this study,uniaxial tensile tests were performed on commercially pure titanium at 77 K over a broad strain rate range from 0.001 to 1 s^(-1).A critical strain rate of approximately 0.5 s^(-1)was identified,above which ductility exhibits a pronounced reduction,whereas below this threshold,ductility remains relatively stable.Through comprehensive analyses of strain evolution,deformed microstructure,and fracture morphology,this behavior is attributed to severe localized adiabatic heating resulting from inhomogeneous deformation,rather than conventional twin or shear mechanisms.
文摘This study deals with the development of a 780-MPa-class hot-rolled advanced high-strength steel(AHSS)with an ultrahigh elongation at break of approximately 30%and strength-ductility product exceeding 24 GPa·%,indicating the excellent formability of the newly developed AHSS.The microstructure of the newly developed 780-MPa-class AHSS consists mainly of the triplex phase of ferrite,bainite,and retained austenite with a volume fraction of 10%±2%.The stability of the retained austenite in the newly developed AHSS is much higher than that of conventional transformation-induced plasticity steels,in which the retained austenite is prone to transformation into martensite under deformation.At a pre-strain lower than 1.2%,the volume fraction of the retained austenite and the elongation at break of the present 780-MPa-class AHSS remain almost unchanged,showing a high tolerance in the process window during leveling or straightening.Therefore,the present 780-MPa-class AHSS is particularly suitable for the production of components with complex shapes.
基金funded by the Department of Energy Office of Vehicle Technologies under the Automotive Lightweighting Materials Program。
文摘High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicles enhances structural reliability and cost efficiency.However,HPDC Mg alloys face challenges related to casting defects such as porosity,cold shuts,and oxides.These defects influence tensile strength and ductility,depending on their location and size.This study employs finite element(FE)modeling to investigate how a dominant large pore,its position,and the sample size affect the ductility of thin-walled HPDC Mg.Motivated by the ductility variations reported in literature and the experimental findings on AM60 castings,synthetic microstructure-based models are used to assess the effects of different pore sizes and locations.The results indicate the presence of three different regions based on the large pore size and model size:1)a region dominated by the effects of the large pore,2)a plateau region dominated by pore interactions,and 3)a transient region between these two effects.A threshold distance from the sample edge (d≈0.9√D·L)is proposed,within which a large pore can significantly reduce ductility.Additionally,large pores near edges contribute to ductility variations in Mg castings.
基金financially supported by the National Natural Science Foundation of China(No.51974078)the Liaoning Province Science and Technology Plan Joint Program(Key Research and Development Program Project,Nos.2022 JH25/10200003 and 2023 JH2/101800058)the Fundamental Research Funds for the Central Universities(No.N25YJS003).
文摘High temperature tensile were performed by using a thermo-mechanical GW1600 to simulate the deformation of Ti microalloy steels at high temperatures and low deformation rates similar to those during continuous casting.An equivalent austenite diameter was proposed,taking into account the weakening effects of proeutectoid ferrite films and Ti carbonitride precipitation.Based on this,a hot ductility prediction model for the slab was established to investigated hot ductility.The results show that as Ti content increases,the hot ductility of Ti microalloy steel initially increases and then decreases.At low Ti content,the pinning effect of Ti carbonitrides increases with the increase in Ti content,which inhibits grain coarsening for improving hot ductility.As Ti content increases,the size of carbonitrides grows,weakening the pinning effect and leading to austenite grain coarsening.Simultaneously,the formation of Ti carbonitrides inhibits proeutectoid ferrite film formation,leading to a reduction in its thickness.These combined factors reduce the hot ductility of the continuous casting steel.According to the hot ductility prediction model,in order of severity,the factors affecting hot ductility are:proeutectoid ferrite film,chain-like nanoscale Ti carbonitrides,austenite grain size,and dispersed nanoscale Ti carbonitrides.An accuracy error of less than 10%is shown by the model.
基金financially supported by the National Key R&D program(No.2022YFB3707501)the GDAS’Project of Science and Technology(No.2022GDASZH-2022010202)the Guangdong Provincial Project(Nos.2022A0505050053,2021B1515120071,and 2020B1515130007)。
文摘Austenitic stainless steels(ASSs)are widely used in various in-dustries such as aerospace,nuclear energy,food,and biotechnol-ogy owing to their exceptional combination of corrosion resistance,weldability,toughness,and formability[1,2].However,a signifi-cant drawback of ASSs is their low yield strength,which limits their applications in extreme environments[3].Grain boundary(GB)engineering plays a crucial role in enhancing the strength of ASSs[4,5].For instance,grain refinement techniques such as cold rolling followed by annealing[6],severe plastic deformation(SPD)[7],and surface mechanical attrition/rolling treatments[8,9]introduce high-angle GBs(HAGBs)into ASSs,thereby improving their strength.However,the high density of HAGBs limits their ca-pacity for dislocation storage and multiplication,leading to a sig-nificant loss of ductility[10,11].Additionally,several studies have shown that twin boundaries(TBs)can simultaneously enhance the strength,toughness,and corrosion resistance of ASSs[12,13].
