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
Reinforcement distribution tailoring has been proven effective in strengthening and toughening titanium matrix composites(TMCs).In this work,the analysis of the Ti64(Ti-6Al-4V)-B phase diagram indicated that B content...Reinforcement distribution tailoring has been proven effective in strengthening and toughening titanium matrix composites(TMCs).In this work,the analysis of the Ti64(Ti-6Al-4V)-B phase diagram indicated that B content dominates the TiB distribution.With this philosophy,B content regulation was applied to tailor homogeneous and network structures in Ti64-B composites fabricated via laser-directed energy deposition additive manufacturing(AM).The unique plate-like TiB attends inhomogeneous composites(Ti64–0.05B).However,in network composite(Ti64–0.25B),the TiB whisker(TiBw)arranges along priorβ-Ti grains with the same orientation.Moreover,the synergistic improvement of strength(988 MPa→1202 MPa),stiffness(106 GPa→116 GPa),hardness(325 HV→362 HV),and uniform elongation(5%→7.8%)were achieved.This work exhibited a balanced strength/ductility trade-off,which provides a good guide on microstructure tailoring.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
How to achieve high-entropy alloys(HEAs)with ultrahigh strength and ductility is a challenging issue.Precipitation strengthening is one of the methods to significantly enhance strength,but unfortunately,ductility will...How to achieve high-entropy alloys(HEAs)with ultrahigh strength and ductility is a challenging issue.Precipitation strengthening is one of the methods to significantly enhance strength,but unfortunately,ductility will be lost.To overcome the strength-ductility trade-off,the strategy of this study is to induce the formation of high-density nanoprecipitates through dual aging(DA),triggering multiple deformation mechanisms,to obtain HEAs with ultrahigh strength and ductility.First,the effect of precold deformation on precipitation behavior was studied using Ni_(35)(CoFe)_(55)V_(5)Nb_(5)(at.%)HEAas the object.The results reveal that the activation energy of recrystallization is 112.2 kJ/mol.As the precold-deformation amount increases from 15%to 65%,the activation energy of precipitation gradually decreases from 178.8 to 159.7 kJ/mol.The precipitation time shortens,the size of the nanoprecipitate decreases,and the density increases.Subsequently,the thermal treatment parameters were optimized,and the DA process was customized based on the effect of precold deformation on precipitation behavior.High-density L1_(2) nanoprecipitates(~3.21×10^(25) m^(-3))were induced in the 65% precold-deformed HEA,which led to the simultaneous formation of twins and stacking fault(SF)networks during deformation.The yield strength(YS),ultimate tensile strength,and ductility of the DA-HEA are~2.0 GPa,~2.2 GPa,and~12.3%,respectively.Compared with the solid solution HEA,the YS of the DA-HEA increased by 1,657 MPa,possessing an astonishing increase of~440%.The high YS stems from the precipitation strengthening contributed by the L1_(2) nanoprecipitates and the dislocation strengthening contributed by precold deformation.The synergistically enhanced ductility stems from the high strain-hardening ability under the dual support of twinning-induced plasticity and SF-induced plasticity.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
A novel triplex heat treatment was designed to simultaneously improve the high-temperature strength and ductility of titanium matrix composites(TMCs)by modulating the microstructure and(TiB+TiC)reinforcements and prom...A novel triplex heat treatment was designed to simultaneously improve the high-temperature strength and ductility of titanium matrix composites(TMCs)by modulating the microstructure and(TiB+TiC)reinforcements and promoting the precipitation of(Ti,Zr)_(6)Si_(3) silicides and theα2 phase.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
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
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
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].
The trade-off between strength and ductility has long been a challenge for Mg alloy.To address this issue,bimodal-structured AZ80 Mg alloys with varying heterogeneity levels were fabricated via low-temperature extrusi...The trade-off between strength and ductility has long been a challenge for Mg alloy.To address this issue,bimodal-structured AZ80 Mg alloys with varying heterogeneity levels were fabricated via low-temperature extrusion in this work.The results reveal the microstructure comprising second-phase particle(SP_(p),β-Mg_(17)Al_(12)and Mg_(3) Mn_(2) Al_(18))-reinforced fine grains(FGs)FGs and SP_(p)-free coarse grains(CGs),with the heterogeneity level decreasing as extrusion temperature increases.As the heterogeneity level decreases,the synergistic deformation capacity initially improves,reaching a maximum at the moderate heterogeneity level of 0.31 GPa and 0.238,and then declines.This exceptional capacity is attributed to the hetero-deformation induced(HDI)stress,which effectively alleviates the strain gradients by activating〈c+a〉dislocations and non-basal〈a〉dislocations during deformation.An optimal combination of 287 MPa in yield strength,393 MPa in ultimate tensile strength,and 14.96%in elongation is achieved in the alloy with a moderate heterogeneity level.The excellent strength-ductility synergy originates from the enhanced capacity of dislocations accumulation driven by remarkable capacity of synergistic deformation and the synergistic strengthening mechanisms.This work provides a new insight into the design of bimodal structure to produce high-performance Mg alloys.展开更多
Insufficient metallurgical compatibility between Zr and Ni can lead to the formation of brittle welds and introduce thermal stress-related challenges during the electron beam welding process.Through the implementation...Insufficient metallurgical compatibility between Zr and Ni can lead to the formation of brittle welds and introduce thermal stress-related challenges during the electron beam welding process.Through the implementation of beam deflection and vibration,a transformation was achieved in the primary Ni_(5)Zr dendrite structure,transitioning from a mass into a layered configuration,consequently resulting in the formation of an ultrafine-grained eutectic−dendrite complex structure.It is revealed that the enhanced strength−ductility synergy of this structure significantly contributes to the high tensile strength and improved plasticity observed in the welded joints.As a result,the welding cracks are effectively mitigated,and notable advancements are achieved in the mechanical properties of Zr/Ni joints,elevating the tensile strength of the joints from 36.4 to 189 MPa.This research not only highlights the potential of this technique in enhancing the strength and ductility of Zr/Ni welded joints but also serves as a valuable reference for future investigations involving welding applications of dissimilar metals.展开更多
Overcoming the strength and ductility trade-off is conducive to expanding the application prospects of the Mg matrix composites.A new approach of using the master alloy containing particulate reinforcements to achieve...Overcoming the strength and ductility trade-off is conducive to expanding the application prospects of the Mg matrix composites.A new approach of using the master alloy containing particulate reinforcements to achieve the strength and ductility synergy in the Mg matrix composites was proposed,which can induce the grain size bimodal structure by regulating the dynamic recrystallization(DRX).Specifically,a novel AlN-Al master alloy was prepared via powder metallurgy to fabricate the AlN/ZK60 composite,and the effects of adding the AlN-Al master alloy on microstructure evolution related to the strength and ductility synergy in the composite were thoughtfully investigated,involving precipitation,grain size,and DRX behavior.The reaction between the Al in the master alloy and the Zr in the ZK60 Mg alloy suppressed the grain refinement,and the coarse grains were further formed after the solution treatment on the as-cast composite.Subsequently,deformation heterogeneity between the AlN and Mg matrix during the hot extrusion induced discontinuous dynamic recrystallization(DDRX)and promoted fine grain fraction.The combination formed the bimodal structure in the AlN/ZK60 composite,and coarse and fine grains acted as hard and soft zones,respectively,during the room temperature deformation.The hard zone was enhanced by the basal texture strengthening,and the ductility was improved due to the promotion of the basalslipping in the soft zone,jointly leading to the strength and ductility synergy in the AlN/ZK60 composite for the ultimate tensile strength increased by ~7.4%while maintaining the same elongation compared with the ZK60 Mg alloy.展开更多
This article reports a systematic investigation on the relationship between the microstructure evolution and mechanical properties of as-cast Mg-9.5Gd-2.3Y-1Zn-0.5Zr(VW92,wt.%)alloy during aging treatment.The results ...This article reports a systematic investigation on the relationship between the microstructure evolution and mechanical properties of as-cast Mg-9.5Gd-2.3Y-1Zn-0.5Zr(VW92,wt.%)alloy during aging treatment.The results indicate that the alloy exhibits obvious double peak-aging characteristics at 180℃,200℃,and 220℃;the first peak-aging appeared at 96 h,48 h,and 48 h,respectively,while the second peak-aging occurred at 204 h,180 h,and 180 h,respectively.Moreover,the strengths of the first peak-aging were higher than those of the second peak-aging.Consequently,the first peak-aging at 200℃ achieved the best mechanical properties,with ultimate tensile strength(UTS),yield strength(YS),and elongation(EL)of 380(±2.0)MPa,255(±1.8)MPa,and 12.8(±1.7)%,respectively.While the strength decreased in the second peak-aging,the elongation increased to 17.2(±0.5)%.The first peak-aging strengthening is ascribed to the participation of the nano-β' phases in the matrix and the long period stacking ordered(LPSO)phases at grain boundaries(GBs).Additionally,the second peak-aging strengthening is associated with the emergence of a relatively new 3D structure comprising longchain-like structural phases β'+β'_(F) tβ_(1),γ' phases,and LPSO phases within the grain,combined with the fine and uniform LPSO phases at the GBs.展开更多
Phosphor bronze is a commonly used elastic copper alloy,widely applied in electronic connectors and terminals[1-4].With the rapid development of 5 G mobile communication technology and the new energy vehicle industry,...Phosphor bronze is a commonly used elastic copper alloy,widely applied in electronic connectors and terminals[1-4].With the rapid development of 5 G mobile communication technology and the new energy vehicle industry,the size requirements for connectors have been reduced,while the demand for strength has gradually increased[5].This requires the alloy to possess higher strength and better deformability.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
1.Introduction The precipitation of κ-carbides is critical for the deformation behavior of Fe-Mn-Al-C austenitic low-density steels[1-5].Ther-momechanical treatment can significantly influence the distribution,size,a...1.Introduction The precipitation of κ-carbides is critical for the deformation behavior of Fe-Mn-Al-C austenitic low-density steels[1-5].Ther-momechanical treatment can significantly influence the distribution,size,and morphology of κ-carbides,and thus regulate the mechanical properties[1,4,6-8].Intragranular κ-carbides precipitate through either nucleation and growth mechanisms[9]or spinodal decomposition[3,5],depending on thermodynamic conditions.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
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.
文摘Reinforcement distribution tailoring has been proven effective in strengthening and toughening titanium matrix composites(TMCs).In this work,the analysis of the Ti64(Ti-6Al-4V)-B phase diagram indicated that B content dominates the TiB distribution.With this philosophy,B content regulation was applied to tailor homogeneous and network structures in Ti64-B composites fabricated via laser-directed energy deposition additive manufacturing(AM).The unique plate-like TiB attends inhomogeneous composites(Ti64–0.05B).However,in network composite(Ti64–0.25B),the TiB whisker(TiBw)arranges along priorβ-Ti grains with the same orientation.Moreover,the synergistic improvement of strength(988 MPa→1202 MPa),stiffness(106 GPa→116 GPa),hardness(325 HV→362 HV),and uniform elongation(5%→7.8%)were achieved.This work exhibited a balanced strength/ductility trade-off,which provides a good guide on microstructure tailoring.
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 Project(No.2023YFA1600082)the National Natural Science Foundation of China(Nos.U2141207,52001083,52171111)+3 种基金Natural Science Foundation of Heilongjiang(No.YQ2023E026)the Fundamental Research Funds for the Central Universities(No.3072022JIP1002)Key Laboratory Found of the Ministry of Industry and Information Technology(No.GXB202201)Youth Talent Project of China National Nuclear Corporation(No.CNNC2021YTEP-HEU01).
文摘How to achieve high-entropy alloys(HEAs)with ultrahigh strength and ductility is a challenging issue.Precipitation strengthening is one of the methods to significantly enhance strength,but unfortunately,ductility will be lost.To overcome the strength-ductility trade-off,the strategy of this study is to induce the formation of high-density nanoprecipitates through dual aging(DA),triggering multiple deformation mechanisms,to obtain HEAs with ultrahigh strength and ductility.First,the effect of precold deformation on precipitation behavior was studied using Ni_(35)(CoFe)_(55)V_(5)Nb_(5)(at.%)HEAas the object.The results reveal that the activation energy of recrystallization is 112.2 kJ/mol.As the precold-deformation amount increases from 15%to 65%,the activation energy of precipitation gradually decreases from 178.8 to 159.7 kJ/mol.The precipitation time shortens,the size of the nanoprecipitate decreases,and the density increases.Subsequently,the thermal treatment parameters were optimized,and the DA process was customized based on the effect of precold deformation on precipitation behavior.High-density L1_(2) nanoprecipitates(~3.21×10^(25) m^(-3))were induced in the 65% precold-deformed HEA,which led to the simultaneous formation of twins and stacking fault(SF)networks during deformation.The yield strength(YS),ultimate tensile strength,and ductility of the DA-HEA are~2.0 GPa,~2.2 GPa,and~12.3%,respectively.Compared with the solid solution HEA,the YS of the DA-HEA increased by 1,657 MPa,possessing an astonishing increase of~440%.The high YS stems from the precipitation strengthening contributed by the L1_(2) nanoprecipitates and the dislocation strengthening contributed by precold deformation.The synergistically enhanced ductility stems from the high strain-hardening ability under the dual support of twinning-induced plasticity and SF-induced plasticity.
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 Key R&D program of China(No.2022YFB3705704)the Natural Science Foundation of Heilongjiang Province of China(No.YQ2023E007)+2 种基金the National Natural Science Foundation of China(Nos.52201116,52071228 and 52271118)the State Key Laboratory of Advanced Welding and Joining,the Harbin Institute of Technology(No.AWJ-23M24)the funding Shi Changxu Innovation Center for Advanced Materials(No.SCXKFJJ202213)。
文摘A novel triplex heat treatment was designed to simultaneously improve the high-temperature strength and ductility of titanium matrix composites(TMCs)by modulating the microstructure and(TiB+TiC)reinforcements and promoting the precipitation of(Ti,Zr)_(6)Si_(3) silicides and theα2 phase.
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 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.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funded by the Guangdong Province general university Young Innovative Talents Program Project(2024KQNCX153)Postdoctoral Research Start-up Funds of Dongguan University of Technology。
文摘The trade-off between strength and ductility has long been a challenge for Mg alloy.To address this issue,bimodal-structured AZ80 Mg alloys with varying heterogeneity levels were fabricated via low-temperature extrusion in this work.The results reveal the microstructure comprising second-phase particle(SP_(p),β-Mg_(17)Al_(12)and Mg_(3) Mn_(2) Al_(18))-reinforced fine grains(FGs)FGs and SP_(p)-free coarse grains(CGs),with the heterogeneity level decreasing as extrusion temperature increases.As the heterogeneity level decreases,the synergistic deformation capacity initially improves,reaching a maximum at the moderate heterogeneity level of 0.31 GPa and 0.238,and then declines.This exceptional capacity is attributed to the hetero-deformation induced(HDI)stress,which effectively alleviates the strain gradients by activating〈c+a〉dislocations and non-basal〈a〉dislocations during deformation.An optimal combination of 287 MPa in yield strength,393 MPa in ultimate tensile strength,and 14.96%in elongation is achieved in the alloy with a moderate heterogeneity level.The excellent strength-ductility synergy originates from the enhanced capacity of dislocations accumulation driven by remarkable capacity of synergistic deformation and the synergistic strengthening mechanisms.This work provides a new insight into the design of bimodal structure to produce high-performance Mg alloys.
基金supported by the National Natural Science Foundation of China(No.52375322).
文摘Insufficient metallurgical compatibility between Zr and Ni can lead to the formation of brittle welds and introduce thermal stress-related challenges during the electron beam welding process.Through the implementation of beam deflection and vibration,a transformation was achieved in the primary Ni_(5)Zr dendrite structure,transitioning from a mass into a layered configuration,consequently resulting in the formation of an ultrafine-grained eutectic−dendrite complex structure.It is revealed that the enhanced strength−ductility synergy of this structure significantly contributes to the high tensile strength and improved plasticity observed in the welded joints.As a result,the welding cracks are effectively mitigated,and notable advancements are achieved in the mechanical properties of Zr/Ni joints,elevating the tensile strength of the joints from 36.4 to 189 MPa.This research not only highlights the potential of this technique in enhancing the strength and ductility of Zr/Ni welded joints but also serves as a valuable reference for future investigations involving welding applications of dissimilar metals.
基金the funding supported by the National Natural Science Foundation of China(No.52161145407,52175285,52305335,52171097).
文摘Overcoming the strength and ductility trade-off is conducive to expanding the application prospects of the Mg matrix composites.A new approach of using the master alloy containing particulate reinforcements to achieve the strength and ductility synergy in the Mg matrix composites was proposed,which can induce the grain size bimodal structure by regulating the dynamic recrystallization(DRX).Specifically,a novel AlN-Al master alloy was prepared via powder metallurgy to fabricate the AlN/ZK60 composite,and the effects of adding the AlN-Al master alloy on microstructure evolution related to the strength and ductility synergy in the composite were thoughtfully investigated,involving precipitation,grain size,and DRX behavior.The reaction between the Al in the master alloy and the Zr in the ZK60 Mg alloy suppressed the grain refinement,and the coarse grains were further formed after the solution treatment on the as-cast composite.Subsequently,deformation heterogeneity between the AlN and Mg matrix during the hot extrusion induced discontinuous dynamic recrystallization(DDRX)and promoted fine grain fraction.The combination formed the bimodal structure in the AlN/ZK60 composite,and coarse and fine grains acted as hard and soft zones,respectively,during the room temperature deformation.The hard zone was enhanced by the basal texture strengthening,and the ductility was improved due to the promotion of the basalslipping in the soft zone,jointly leading to the strength and ductility synergy in the AlN/ZK60 composite for the ultimate tensile strength increased by ~7.4%while maintaining the same elongation compared with the ZK60 Mg alloy.
基金supported by National Natural Science Foundation of China(No.U21A2048)the Science and Technology Research Program of the Chongqing Municipal Education Commission(No.KJZDK202201108)+2 种基金Academician in Chongqing Leaded Guidance Project of Science,Technology Innovation(No.CSTB2023YSZX-JCX0006)the Science and Technology Research Project of Chongqing Municipal Education Commission(No.KJQN202101126)Chongqing Natural Science Foundation(No.CSTB2024NSCQ-MSX0574).
文摘This article reports a systematic investigation on the relationship between the microstructure evolution and mechanical properties of as-cast Mg-9.5Gd-2.3Y-1Zn-0.5Zr(VW92,wt.%)alloy during aging treatment.The results indicate that the alloy exhibits obvious double peak-aging characteristics at 180℃,200℃,and 220℃;the first peak-aging appeared at 96 h,48 h,and 48 h,respectively,while the second peak-aging occurred at 204 h,180 h,and 180 h,respectively.Moreover,the strengths of the first peak-aging were higher than those of the second peak-aging.Consequently,the first peak-aging at 200℃ achieved the best mechanical properties,with ultimate tensile strength(UTS),yield strength(YS),and elongation(EL)of 380(±2.0)MPa,255(±1.8)MPa,and 12.8(±1.7)%,respectively.While the strength decreased in the second peak-aging,the elongation increased to 17.2(±0.5)%.The first peak-aging strengthening is ascribed to the participation of the nano-β' phases in the matrix and the long period stacking ordered(LPSO)phases at grain boundaries(GBs).Additionally,the second peak-aging strengthening is associated with the emergence of a relatively new 3D structure comprising longchain-like structural phases β'+β'_(F) tβ_(1),γ' phases,and LPSO phases within the grain,combined with the fine and uniform LPSO phases at the GBs.
基金support of the Natural Science Foundation of China(Nos.U23A20611 and 52071050)the Innovation and Entrepreneurship of High-level Talents Project of Dalian(No.2020RD07)the Science and Technology Innovation Project of Ningbo(No.2024Z077).
文摘Phosphor bronze is a commonly used elastic copper alloy,widely applied in electronic connectors and terminals[1-4].With the rapid development of 5 G mobile communication technology and the new energy vehicle industry,the size requirements for connectors have been reduced,while the demand for strength has gradually increased[5].This requires the alloy to possess higher strength and better deformability.
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].
基金financially supported by the National Natural Science Foundation of China(grant No 52171108)the Natural Science Foundation of Liaoning Province(grant No 2023-MSBA-037)the Fundamental Research Funds for the Central University(grant No N2402007).
文摘1.Introduction The precipitation of κ-carbides is critical for the deformation behavior of Fe-Mn-Al-C austenitic low-density steels[1-5].Ther-momechanical treatment can significantly influence the distribution,size,and morphology of κ-carbides,and thus regulate the mechanical properties[1,4,6-8].Intragranular κ-carbides precipitate through either nucleation and growth mechanisms[9]or spinodal decomposition[3,5],depending on thermodynamic conditions.
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.
