We discovered two distinctive features in the mechanical properties of extruded Mg alloys containing a long-period stacking ordered(LPSO)phase,which are highly desirable for a new class of high-strength,lightweight ma...We discovered two distinctive features in the mechanical properties of extruded Mg alloys containing a long-period stacking ordered(LPSO)phase,which are highly desirable for a new class of high-strength,lightweight materials.First,the Mg/LPSO-extruded alloy shows greater elongation compared to other Mg solid-solution-extruded alloys when a certain high strength is required.Second,the simultaneous achievement of high strength and large elongation in the Mg/LPSO-extruded alloy enhances with a reduction in extrusion speed.In this study,the physical origins of these features were examined,focusing on how changes in the microstructure affect the mechanical properties of the extruded alloys.Our findings clarify that the LPSO phase contributes not only to increased strength but also to enhanced elongation through an increase in the work-hardening rate,a mechanism we termed aanisotropic mechanical property-induced ductilizationo(AMID).Until now,most efforts to improve the ductility of Mg materials have focused on achieving aisotropic mechanical propertieso via grain refinement.Based on our results,we propose an entirely opposite approach:increasing the elongation of Mg alloy by locally enhancing theiraanisotropic mechanical propertieso through the AMID mechanism.Computational analysis further suggests that reducing the diameter of Mg-worked grains should effectively improving elongation in Mg/LPSO alloys with a high volume fraction of Mg-worked grains.展开更多
Niobium(Nb)is sensitive to even minute quantities of silicon(Si)solutes,which are known to induce pronounced hardening.However,the underlying mechanism for hardening remains elusive since the ef-fect of Si solutes on ...Niobium(Nb)is sensitive to even minute quantities of silicon(Si)solutes,which are known to induce pronounced hardening.However,the underlying mechanism for hardening remains elusive since the ef-fect of Si solutes on dislocation behavior is unclear.Here,using tensile testing,in-situ microscopy and nanomechanical testing,the behavior of dislocations in dilute Nb-Si alloys,containing from 0 at.%to 0.8 at.%Si,is investigated.We show that the hardness,strength and strain hardening rate increase from two to four times,while the uniform elongation in tension only reduces 50%as the Si content increases.Dislocations evolve from complex entangled patterns in Nb to parallel long-straight screw dislocation-dominated structures in Nb-Si alloys.In-situ indentation reveals that the origins of the marked harden-ing in Nb-Si alloy are the reduction of dislocation mobility and cross-slip propensity.Large densities of dislocation debris-superjogs and loops introduced throughout the sample during warm rolling and an-nealing are found to provide active internal dislocation sources,which explain the minimal ductility loss seen in these Nb-Si alloys.These findings can help guide the alloy design of high-performance refractory materials for extreme temperature applications.展开更多
Dislocation source-limited hardening and ductilization is an effective strategy to obtain superior strength-ductility synergy in some engineering structural metals. Recent works demonstrated that the synergy could be ...Dislocation source-limited hardening and ductilization is an effective strategy to obtain superior strength-ductility synergy in some engineering structural metals. Recent works demonstrated that the synergy could be enhanced by grain-size reduction. However, the mechanism of grain-size dependence is still a mystery. In this work, bulk pure Ni produced by electrodeposition and subsequent annealing, with grain sizes ranging from ∼20 nm to ∼20 µm, were methodically investigated to unravel the mechanism of the grain-size effect on dislocation source-limited hardening and ductilization. The high-density nano-twinning in the as-electrodeposited nanograined specimens exhibited better thermodynamic stability than the peers with random high-angle grain boundaries, leading to fine recrystallized grains with low-density dislocations. The low dislocation density enabled extra hardening beyond grain boundary strengthening via yield-point behavior with grain sizes ranging from ∼110 nm to ∼10 µm and extra ductilization over ∼500 nm. This work demonstrated that the prerequisite for dislocation source-limited hardening was that the dislocation density of the specimen should be lower than the size-dependent critical value of ((1.1 × 107 /d ) m^(–2), d is the grain size in unit of the meter) where a transition from forest-dominated hardening to dislocation source-limited hardening could occur. On the other hand, dislocation source-limited ductilization only worked when the grain size was comparable to/larger than the theoretical dislocation mean slip distance. Dislocation source-limited ductilization resulted from more room in grains for accumulation of dislocations and deformation nano-stacking faults enabling the higher work hardening rate. This work offered an altogether new avenue to obtain stronger and more ductile metallic materials through utilizing grain-size dependent dislocation source-limited hardening and ductilization.展开更多
The present work investigates the influences of microalloying with rare earths on the mechanical properties of magnesium alloys.The amount of each rare earth element is controlled below 0.4 wt.%in order not to increas...The present work investigates the influences of microalloying with rare earths on the mechanical properties of magnesium alloys.The amount of each rare earth element is controlled below 0.4 wt.%in order not to increase the cost of alloy largely.The synergic effects from the multi-microalloying with rare earths on the mechanical properties are explored.The obtained results show that the as-cast magnesium alloys multi-microalloying with rare earths possesses a quite high ductility with a tensile strain up to 25-30%at room temperature.Moreover,these alloys exhibit much better corrosion resistance than AZ31 alloy.The preliminary in situ neutron diffractions on the deformation of these alloys indicate that the multi-microalloying with rare earths seems to be beneficial for the activation of more slip systems.The deformation becomes more homogeneous and the resultant textures after deformation are weakened.展开更多
This paper reviews recent research on ductility improvement of B-undoped Ni_3Al alloys.Ni_3Al binary alloys with hypostoichiometric compositions show appreciable ductility at room temperature when the samples are prep...This paper reviews recent research on ductility improvement of B-undoped Ni_3Al alloys.Ni_3Al binary alloys with hypostoichiometric compositions show appreciable ductility at room temperature when the samples are prepared by recrystallization annealing after cold pressing,although the alloys with stoichiometric and hyperstoichiometric compositions remain brittle.Melt-spun ribbons with hypostoichiometric compositions contain fine anti-phase domains (APDs),while no APD can be seen in melt-spun ribbons with a hyperstoichiometric composition.The ductility in hypostoichiometric Ni_3Al alloys is associated with low ordering energy of the alloys.The addition of ternary elements,which have been classified as γ formers such as Pd,Pt,Cu,Co and Ag.improves ductility of Ni_3Al alloys.Correspondingly,the microstructure of the melt-spun ribbons consists of fine APDs.The addition of γ' formers such as Si,Ti,Zr,V,Nb and Ta leads to brittle intergranular frac- ture.No APD was observed in the melt-spun ribbons of these ternary alloys.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
A comprehensive analysis of the microstructure and defects of a thixomolded AZ91D alloy was conducted to elucidate their influences on mechanical properties.Samples were made at injection temperatures ranging from 580...A comprehensive analysis of the microstructure and defects of a thixomolded AZ91D alloy was conducted to elucidate their influences on mechanical properties.Samples were made at injection temperatures ranging from 580 to 640℃.X-ray computed tomography was used to visualize pores,and crystal plasticity finite element simulation was adopted for deformation analysis.The microstructure characterizations reveal a hierarchical cell feature composed of α-Mg and eutectic phases.With the increase of injection temperature,large cell content in the material decreases,while the strength of the alloy increases.The underlying mechanism about strength change is that coarse-grained solids experience smaller stress even in hard orientations.The sample fabricated at a moderate temperature of 620℃ exhibits the highest elongation,least quantity and lower local concentration of pores.The detachment and tearing cracks formed at lower injection temperature and defect bands formed at higher injection temperature add additional crack sources and deteriorate the ductility of the materials.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
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
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
The development and deployment of aluminum conductor have been significantly hampered by the contradiction of yield strength,uniform elongation,and electrical conductivity.Herein,we successfully fabricated a pure alum...The development and deployment of aluminum conductor have been significantly hampered by the contradiction of yield strength,uniform elongation,and electrical conductivity.Herein,we successfully fabricated a pure aluminum(Al)clad aluminum alloy(AA)rod with hierarchical compositions and microstructures.The proposed pure Al clad AA rod showcases an optimized combination of yield strength,uniform elongation,and electrical conductivity,i.e.,easing the restriction on improving yield strength,uniform elongation,and electrical conductivity.Compared to existing experiments,uniform elongation improved fourfold,while yield strength increased by 13%and electrical conductivity improved by 2%in terms of the international annealed copper standard(IACS).Microstructural characterizations and theoretical analyses revealed that the optimal performance of the Al clad AA arose from low-density low-angle grain boundaries(LAGBs)in the outer Al and high-density LAGBs with nanoscale precipitations in the inner AA.Our findings offer a compelling strategy for fabricating high-performance aluminum conductors,thereby laying a solid technical foundation for their wide application in power delivery systems.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
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
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
A heterogeneous structure composed of elongated primaryαand secondaryαgrains with a size of 670 nm was produced by subjecting the bimodal microstructure of a titanium alloy to hot rolling,annealing,and aging treatme...A heterogeneous structure composed of elongated primaryαand secondaryαgrains with a size of 670 nm was produced by subjecting the bimodal microstructure of a titanium alloy to hot rolling,annealing,and aging treatments.This heterogeneous structure exhibited significantly improved strength owing to a combination of heterogeneous deformation-induced strengthening and dislocation strengthening.A short-duration high-temperature heat treatment facilitated a synergistic enhancement of yield strength and elongation at both room temperature and 650℃.The fracture elongation at room temperature and 650℃ increased by 36.7% and 130.4%,respectively,compared with that of bimodal microstructure.The stacking of geometrically necessary dislocations with a single slip system at the phase boundary and the longer effective slip length of the dislocations are the reasons for the significant improvement in elongation.The elongated primary α phase in lamellar bimodal microstructure,composed of multiple primary α grains,has better resistance to the anti-fatigue crack initiation effect.展开更多
Precipitation of carbides, nitrides, and carbonitrides is an important factor influencing the formation of surface transverse cracks in the continuous casting of microalloyed steel, affecting the quality and yield of ...Precipitation of carbides, nitrides, and carbonitrides is an important factor influencing the formation of surface transverse cracks in the continuous casting of microalloyed steel, affecting the quality and yield of the final product. Based on previous investigation, the precipitation sequence and temperature, position and mode, as well as the size, morphology, and number of different types of precipitates were reviewed. The effects of C, N, Nb, Ti, and V on the precipitation behavior and surface transverse cracks in continuous casting slabs were summarized, with a particular emphasis on the new achievements concerning Ti addition. The critical amounts of different elements to avoid serious surface cracks during continuous casting were proposed. The control mechanisms and industrial effects of composition optimization, cooling design, and chamfered mold configuration to improve surface transverse cracks in continuous casting slabs were also illustrated, and the recent application of surface microstructure control technology was emphasized. The characteristics, advantages, and shortcomings of existing theoretical and experimental methods in investigating continuous casting surface cracks regarding precipitation are finally discussed, and a new setup with advanced functions is introduced.展开更多
Zn–Ag alloys are highly promising materials for fabricating biodegradable orthopedic implants.Nonetheless,they suffer from inferior strength.A Zn–2.5Ag alloy was alloyed with different contents of Mg(0.08,0.5,and 1 ...Zn–Ag alloys are highly promising materials for fabricating biodegradable orthopedic implants.Nonetheless,they suffer from inferior strength.A Zn–2.5Ag alloy was alloyed with different contents of Mg(0.08,0.5,and 1 wt.%)and then processed by equal channel angular pressing.Tensile tests and microstructure observation were conducted to investigate the impact of Mg addition on the microstructure and mechanical properties of Zn–2.5Ag alloy.Zn–2.5Ag alloy exhibits an ultrahigh elongation(EL)of 120.4%but a poor yield strength(YS)of 90.1 MPa,because of phase boundary sliding(PBS).Mg addition inhibits PBS and thus dramatically enhances YS but lowers EL.Specifically,YS of Zn–2.5Ag alloys containing Mg of 0.08%,0.5%,and 1%is 257.0,291.8,and 322.6 MPa,respectively.The alloys with 0.08%and 0.5%Mg possess an EL of around 30%,while the alloy with 1%Mg has an EL of only 11.0%.YS and EL of Zn–2.5Ag–0.5Mg alloy surpass that needed by orthopedic implants by 45.9%and 106.0%,respectively.Grain refinement strengthening is the main contributor to high strength.It is speculated that deformation twinning suppression and<c+a>pyramidal slip activation contribute to good ductility.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
基金supported by the Japan Science and Technology Agency(JST),CREST(grant number JPMJCR2094)。
文摘We discovered two distinctive features in the mechanical properties of extruded Mg alloys containing a long-period stacking ordered(LPSO)phase,which are highly desirable for a new class of high-strength,lightweight materials.First,the Mg/LPSO-extruded alloy shows greater elongation compared to other Mg solid-solution-extruded alloys when a certain high strength is required.Second,the simultaneous achievement of high strength and large elongation in the Mg/LPSO-extruded alloy enhances with a reduction in extrusion speed.In this study,the physical origins of these features were examined,focusing on how changes in the microstructure affect the mechanical properties of the extruded alloys.Our findings clarify that the LPSO phase contributes not only to increased strength but also to enhanced elongation through an increase in the work-hardening rate,a mechanism we termed aanisotropic mechanical property-induced ductilizationo(AMID).Until now,most efforts to improve the ductility of Mg materials have focused on achieving aisotropic mechanical propertieso via grain refinement.Based on our results,we propose an entirely opposite approach:increasing the elongation of Mg alloy by locally enhancing theiraanisotropic mechanical propertieso through the AMID mechanism.Computational analysis further suggests that reducing the diameter of Mg-worked grains should effectively improving elongation in Mg/LPSO alloys with a high volume fraction of Mg-worked grains.
基金supported by the National Natu-ral Science Foundation of China(Nos.51971170 and 51922082)the Shaanxi Science&Technology Innovation Project(No.2022QFY10-03)+1 种基金the assistance of Dr.Ping-Jiong Yang during the earlier stage of this project.S.O.and S.S.were supported by the Ministry of Education,Culture,Sport,Sci-ence and Technology of Japan programs(Nos.JPMXP1122684766,JPMXP1020230325,and JPMXP1020230327)JSPS KAKENHI(No.JP23H00161).S.S.was supported by JSPS KAKENHI(Nos.21K14042 and 22H05283).S.S.and S.O.wish to thank Dr.Tomo-hito Tsuru for discussions regarding NNP creation.
文摘Niobium(Nb)is sensitive to even minute quantities of silicon(Si)solutes,which are known to induce pronounced hardening.However,the underlying mechanism for hardening remains elusive since the ef-fect of Si solutes on dislocation behavior is unclear.Here,using tensile testing,in-situ microscopy and nanomechanical testing,the behavior of dislocations in dilute Nb-Si alloys,containing from 0 at.%to 0.8 at.%Si,is investigated.We show that the hardness,strength and strain hardening rate increase from two to four times,while the uniform elongation in tension only reduces 50%as the Si content increases.Dislocations evolve from complex entangled patterns in Nb to parallel long-straight screw dislocation-dominated structures in Nb-Si alloys.In-situ indentation reveals that the origins of the marked harden-ing in Nb-Si alloy are the reduction of dislocation mobility and cross-slip propensity.Large densities of dislocation debris-superjogs and loops introduced throughout the sample during warm rolling and an-nealing are found to provide active internal dislocation sources,which explain the minimal ductility loss seen in these Nb-Si alloys.These findings can help guide the alloy design of high-performance refractory materials for extreme temperature applications.
基金financially supported by the National Natural Science Foundation of China(Nos.51827801 and 52171160)the National Key Research Development Program of China(No.2016YFB0700203).
文摘Dislocation source-limited hardening and ductilization is an effective strategy to obtain superior strength-ductility synergy in some engineering structural metals. Recent works demonstrated that the synergy could be enhanced by grain-size reduction. However, the mechanism of grain-size dependence is still a mystery. In this work, bulk pure Ni produced by electrodeposition and subsequent annealing, with grain sizes ranging from ∼20 nm to ∼20 µm, were methodically investigated to unravel the mechanism of the grain-size effect on dislocation source-limited hardening and ductilization. The high-density nano-twinning in the as-electrodeposited nanograined specimens exhibited better thermodynamic stability than the peers with random high-angle grain boundaries, leading to fine recrystallized grains with low-density dislocations. The low dislocation density enabled extra hardening beyond grain boundary strengthening via yield-point behavior with grain sizes ranging from ∼110 nm to ∼10 µm and extra ductilization over ∼500 nm. This work demonstrated that the prerequisite for dislocation source-limited hardening was that the dislocation density of the specimen should be lower than the size-dependent critical value of ((1.1 × 107 /d ) m^(–2), d is the grain size in unit of the meter) where a transition from forest-dominated hardening to dislocation source-limited hardening could occur. On the other hand, dislocation source-limited ductilization only worked when the grain size was comparable to/larger than the theoretical dislocation mean slip distance. Dislocation source-limited ductilization resulted from more room in grains for accumulation of dislocations and deformation nano-stacking faults enabling the higher work hardening rate. This work offered an altogether new avenue to obtain stronger and more ductile metallic materials through utilizing grain-size dependent dislocation source-limited hardening and ductilization.
文摘The present work investigates the influences of microalloying with rare earths on the mechanical properties of magnesium alloys.The amount of each rare earth element is controlled below 0.4 wt.%in order not to increase the cost of alloy largely.The synergic effects from the multi-microalloying with rare earths on the mechanical properties are explored.The obtained results show that the as-cast magnesium alloys multi-microalloying with rare earths possesses a quite high ductility with a tensile strain up to 25-30%at room temperature.Moreover,these alloys exhibit much better corrosion resistance than AZ31 alloy.The preliminary in situ neutron diffractions on the deformation of these alloys indicate that the multi-microalloying with rare earths seems to be beneficial for the activation of more slip systems.The deformation becomes more homogeneous and the resultant textures after deformation are weakened.
文摘This paper reviews recent research on ductility improvement of B-undoped Ni_3Al alloys.Ni_3Al binary alloys with hypostoichiometric compositions show appreciable ductility at room temperature when the samples are prepared by recrystallization annealing after cold pressing,although the alloys with stoichiometric and hyperstoichiometric compositions remain brittle.Melt-spun ribbons with hypostoichiometric compositions contain fine anti-phase domains (APDs),while no APD can be seen in melt-spun ribbons with a hyperstoichiometric composition.The ductility in hypostoichiometric Ni_3Al alloys is associated with low ordering energy of the alloys.The addition of ternary elements,which have been classified as γ formers such as Pd,Pt,Cu,Co and Ag.improves ductility of Ni_3Al alloys.Correspondingly,the microstructure of the melt-spun ribbons consists of fine APDs.The addition of γ' formers such as Si,Ti,Zr,V,Nb and Ta leads to brittle intergranular frac- ture.No APD was observed in the melt-spun ribbons of these ternary alloys.
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(Nos.51825101,52001202)the National Key Research and Development Program of China(No.2021YFA1600900)。
文摘A comprehensive analysis of the microstructure and defects of a thixomolded AZ91D alloy was conducted to elucidate their influences on mechanical properties.Samples were made at injection temperatures ranging from 580 to 640℃.X-ray computed tomography was used to visualize pores,and crystal plasticity finite element simulation was adopted for deformation analysis.The microstructure characterizations reveal a hierarchical cell feature composed of α-Mg and eutectic phases.With the increase of injection temperature,large cell content in the material decreases,while the strength of the alloy increases.The underlying mechanism about strength change is that coarse-grained solids experience smaller stress even in hard orientations.The sample fabricated at a moderate temperature of 620℃ exhibits the highest elongation,least quantity and lower local concentration of pores.The detachment and tearing cracks formed at lower injection temperature and defect bands formed at higher injection temperature add additional crack sources and deteriorate the ductility of the materials.
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 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.12072327,12302497)the National Outstanding Youth Science Fund Project(No.12125206)+2 种基金Major International Joint Research Project(No.W2411003)Fund raised by China Electric Power Research Institute(No.GC80-21-002)CAS Project for Young Scientists in Basic Research(YSBR-096).
文摘The development and deployment of aluminum conductor have been significantly hampered by the contradiction of yield strength,uniform elongation,and electrical conductivity.Herein,we successfully fabricated a pure aluminum(Al)clad aluminum alloy(AA)rod with hierarchical compositions and microstructures.The proposed pure Al clad AA rod showcases an optimized combination of yield strength,uniform elongation,and electrical conductivity,i.e.,easing the restriction on improving yield strength,uniform elongation,and electrical conductivity.Compared to existing experiments,uniform elongation improved fourfold,while yield strength increased by 13%and electrical conductivity improved by 2%in terms of the international annealed copper standard(IACS).Microstructural characterizations and theoretical analyses revealed that the optimal performance of the Al clad AA arose from low-density low-angle grain boundaries(LAGBs)in the outer Al and high-density LAGBs with nanoscale precipitations in the inner AA.Our findings offer a compelling strategy for fabricating high-performance aluminum conductors,thereby laying a solid technical foundation for their wide application in power delivery systems.
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the National Key Research and Development Program of China(Nos.2021YFB3704202,2021YFB3704205)R&D Program of Beijing Municipal Education Commission,China(No.KM 202110005010)+2 种基金Beijing Natural Science Foundation,China(No.2202009)National Natural Science Foundation of China(No.51621003)Basic Research Program of Jiangsu Province,China(No.BK20191148).
文摘A heterogeneous structure composed of elongated primaryαand secondaryαgrains with a size of 670 nm was produced by subjecting the bimodal microstructure of a titanium alloy to hot rolling,annealing,and aging treatments.This heterogeneous structure exhibited significantly improved strength owing to a combination of heterogeneous deformation-induced strengthening and dislocation strengthening.A short-duration high-temperature heat treatment facilitated a synergistic enhancement of yield strength and elongation at both room temperature and 650℃.The fracture elongation at room temperature and 650℃ increased by 36.7% and 130.4%,respectively,compared with that of bimodal microstructure.The stacking of geometrically necessary dislocations with a single slip system at the phase boundary and the longer effective slip length of the dislocations are the reasons for the significant improvement in elongation.The elongated primary α phase in lamellar bimodal microstructure,composed of multiple primary α grains,has better resistance to the anti-fatigue crack initiation effect.
基金supported by the Fundamental Research Funds for the Central Universities(No.FRF-TP-19-017A3)National Natural Science Foundation of China(No.51874026).
文摘Precipitation of carbides, nitrides, and carbonitrides is an important factor influencing the formation of surface transverse cracks in the continuous casting of microalloyed steel, affecting the quality and yield of the final product. Based on previous investigation, the precipitation sequence and temperature, position and mode, as well as the size, morphology, and number of different types of precipitates were reviewed. The effects of C, N, Nb, Ti, and V on the precipitation behavior and surface transverse cracks in continuous casting slabs were summarized, with a particular emphasis on the new achievements concerning Ti addition. The critical amounts of different elements to avoid serious surface cracks during continuous casting were proposed. The control mechanisms and industrial effects of composition optimization, cooling design, and chamfered mold configuration to improve surface transverse cracks in continuous casting slabs were also illustrated, and the recent application of surface microstructure control technology was emphasized. The characteristics, advantages, and shortcomings of existing theoretical and experimental methods in investigating continuous casting surface cracks regarding precipitation are finally discussed, and a new setup with advanced functions is introduced.
基金financial support of the National Natural Science Foundation of China(Nos.52001142 and 51975263).
文摘Zn–Ag alloys are highly promising materials for fabricating biodegradable orthopedic implants.Nonetheless,they suffer from inferior strength.A Zn–2.5Ag alloy was alloyed with different contents of Mg(0.08,0.5,and 1 wt.%)and then processed by equal channel angular pressing.Tensile tests and microstructure observation were conducted to investigate the impact of Mg addition on the microstructure and mechanical properties of Zn–2.5Ag alloy.Zn–2.5Ag alloy exhibits an ultrahigh elongation(EL)of 120.4%but a poor yield strength(YS)of 90.1 MPa,because of phase boundary sliding(PBS).Mg addition inhibits PBS and thus dramatically enhances YS but lowers EL.Specifically,YS of Zn–2.5Ag alloys containing Mg of 0.08%,0.5%,and 1%is 257.0,291.8,and 322.6 MPa,respectively.The alloys with 0.08%and 0.5%Mg possess an EL of around 30%,while the alloy with 1%Mg has an EL of only 11.0%.YS and EL of Zn–2.5Ag–0.5Mg alloy surpass that needed by orthopedic implants by 45.9%and 106.0%,respectively.Grain refinement strengthening is the main contributor to high strength.It is speculated that deformation twinning suppression and<c+a>pyramidal slip activation contribute to good ductility.
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.
