The recently established theory has built clear connections between hardness and toughness and electron structure involving both valence electron concentration(VEC)and core electron count(CEC)in transition metal nitri...The recently established theory has built clear connections between hardness and toughness and electron structure involving both valence electron concentration(VEC)and core electron count(CEC)in transition metal nitride(TMN)ceramics.However,the underlying deformation mechanisms remain unclear.Herein,we conduct in-depth analysis on microstructure evolution during deformation of the high VEC-CEC solution TiMoN coatings having desired combination of high hardness and toughness.The effects of solid solution,preferred orientation linked with symbiotic compressive stress,grain size and dislocations are systematically discussed.We discover that numerous dislocations have been implanted into the nanocrystals of the TiMoN coating during the high-ionization arc deposition.Using two-beam bright-field imaging,we count the dislocation density and confirm occurrence of dislocation multiplication to form effective plastic deformation,which contributes to significant strain hardening,comparable to solid solution hardening,fine-grain hardening and compressive stress hardening.The improved dislocation activities also play a crucial role in enhancing the toughness by providing extra energy dissipation paths.This work gains new insights into the origins of mechanical properties of ceramic coatings and possibility to tune them via defects.展开更多
The Mg-4Y-3RE(WE43)magnesium alloy possesses significant advantages such as high specific strength,excellent shock absorption,strong electromagnetic shielding capabilities and recyclability.However,its close-packed he...The Mg-4Y-3RE(WE43)magnesium alloy possesses significant advantages such as high specific strength,excellent shock absorption,strong electromagnetic shielding capabilities and recyclability.However,its close-packed hexagonal structure leads to poor plasticity at room temperature,which limits its broader engineering applications.Therefore,superplastic forming at high temperatures is used to manufacture the components from this alloy.This study conducted tensile tests on hot-rolled WE43 rare-earth magnesium alloy with coarse grains at various temperatures and strain rates.The high-temperature superplastic properties were characterized,revealing the intrinsic mechanisms of thermal deformation behavior.The results indicate that the best superplasticity is achieved at 460℃.This is attributed to the smallest grain size,the weakest texture,and the relatively uniform distribution of the second phase at this temperature.The influence of strain rate on elongation at temperatures among 440℃∼500℃is not significant as the impact of strain rate is multifaceted.Meanwhile,the elongation can reach up to 367.7±3.7%at a strain rate of 0.01s^(−1),which exhibits the high strain rate superplasticity(HSRS).Under these conditions,the deformation of coarse-grained WE43 rare-earth magnesium alloy is controlled by grain boundary sliding(GBS)and solute drag dislocation creep.Furthermore,the GBS involves deformation coordination mechanisms such as grain boundary diffusion,lattice diffusion,dislocation climbing,and dynamic recrystallization accommodation mechanisms.展开更多
To date,nanostructuring through plastic deformation has rarely been reported in biodegradable zinc(Zn)based alloys that have great potential in load-bearing conditions.Here,typical high-strength Zn-Li-based alloys wer...To date,nanostructuring through plastic deformation has rarely been reported in biodegradable zinc(Zn)based alloys that have great potential in load-bearing conditions.Here,typical high-strength Zn-Li-based alloys were subjected to SPD processes,including equal channel angular pressing(ECAP)and high-pressure torsion(HPT),to achieve nanostructured microstructures.The effects of SPD on the microstructures,mechanical properties,and corrosion behaviors were generally investigated.The two SPD routes resulted in totally different microstructures.ECAPed samples processed at 150℃ exhibited a complicated multilevel structure(nm toμm)with mixed Zn equiaxed grains and lamellar-like eutectoid regions(Zn+α-LiZn_(4)),and HPTed ones(25℃)possessed a fully dynamically recrystallized(DRXed)microstructure with an average grain size below 0.4μm.The tensile strength of the SPD samples could reach 500 MPa.Meanwhile,HPTed samples exhibited extraordinary fracture elongations higher than 100%,because of a different grain boundary sliding deformation mechanism.HPTed samples and ECAPed samples displayed different corrosion patterns,and the former exhibited a much higher corrosion rate in Hank's solution,possibly due to the accelerated corrosion at grain boundaries.In summary,SPD is an efficient way to refine the microstructure of biodegradable Zn-based alloys,possibly improving their performances and clinical applications.展开更多
Lithium metal batteries have been deemed one of the most promising candidates for new-generation batteries,used in mobile devices,electric vehicles,energy storage,etc.However,due to the volume change of active materia...Lithium metal batteries have been deemed one of the most promising candidates for new-generation batteries,used in mobile devices,electric vehicles,energy storage,etc.However,due to the volume change of active materials and external pressure,the electrode materials and interfaces between battery components have high stresses during the cycling process,resulting in large deformation of the lithium metal anode.Herein,we derive insights into the mechanical behaviors of polycrystalline lithium metal.Specifically,the mechanical properties of lithium metal containing Li_(7-x)La_(3)Zr_(2-x)Ta_(x)O_(12)(x=0.2-0.7)(LLZTO)solid-state electrolyte impurities are experimentally investigated.It is found that its strength is governed by impurity content and impurity particle size.In addition,we explore the Hall-Petch and inverse Hall-Petch effects of nanocrystalline lithium through atomic-scale simulations,revealing the plastic deformation mechanism in polycrystalline lithium metal.This fundamental study sheds light on the impurity-modulated mechanical properties and plastic deformation mechanism of polycrystalline lithium metal.展开更多
In order to explore the exact nature of deformation defects previously observed in nanostructured Al-Mg alloys subjected to severe plastic deformation, a more thorough examination of the radiation effect on the format...In order to explore the exact nature of deformation defects previously observed in nanostructured Al-Mg alloys subjected to severe plastic deformation, a more thorough examination of the radiation effect on the formation of the planar defects in the high pressure torsion （HPT） alloys was conducted using high-resolution transmission electron microscopy （HRTEM）. The results show that high density defects in the HRTEM images disappear completely when these images are exposed under the electron beam for some duration of time. At the same time, lattice defects are never observed within no-defect areas even when the beam-exposure increases to the degree that holes appear in the areas. Therefore, it is confirmed that the planar defects observed in the HPT alloys mainly result from the significant plastic deformation and are not due to the radiation effect during HRTEM observation.展开更多
The effects of solid solution on the deformation behavior of binary Mg-xZn(x=0,1,2 wt%)alloys featuring a designated texture that enables extension twinning under tension parallel to the basal pole in most grains,were...The effects of solid solution on the deformation behavior of binary Mg-xZn(x=0,1,2 wt%)alloys featuring a designated texture that enables extension twinning under tension parallel to the basal pole in most grains,were investigated using in-situ neutron diffraction and the EVPSC-TDT model.Neutron diffraction was used to quantitatively track grain-level lattice strains and diffraction intensity changes(related to mechanical twinning)in differently oriented grains of each alloy during cyclic tensile/compressive loadings.These measurements were accurately captured by the model.The stress-strain curves of Mg-1 wt%Zn and Mg-2 wt%Zn alloys show as-expected solid solution strengthening from the addition of Zn compared to pure Mg.The macroscopic yielding and hardening behaviors are explained by alternating slip and twinning modes as calculated by the model.The solid solution's influence on individual deformation modes,including basal〈a〉slip,prismatic〈a〉slip,and extension twinning,was then quantitatively assessed in terms of activity,yielding behavior,and hardening response by combining neutron diffraction results with crystal plasticity predictions.The Mg-1 wt%Zn alloy displays distinct yielding and hardening behavior due to solid solution softening of prismatic〈a〉slip.Additionally,the dependence of extension twinning,in terms of the twinning volume fraction,on Zn content exhibits opposite trends under tensile and compressive loadings.展开更多
An extruded Mg-Gd-Y-Ag alloy was subjected to simple shear extrusion(SSE)at 280℃ to obtain a refined microstructure,with a focus on examining microstructural evolutions through detailed EBSD analysis and TEM.The EBSD...An extruded Mg-Gd-Y-Ag alloy was subjected to simple shear extrusion(SSE)at 280℃ to obtain a refined microstructure,with a focus on examining microstructural evolutions through detailed EBSD analysis and TEM.The EBSD results revealed that the microstructures at the early stages of deformation contained large deformed grains with a significant fraction of low angle grain boundaries developed through dynamic recovery.Continuous dynamic recrystallization(CDRX)was dominant as deformation proceeded.Two kinds of CDRX grains were recognized considering their locations;“GB-type”grains,which formed in the vicinity of the pre-existing boundaries of the deformed grains,and“Core-type”grains,emerging within the interior areas.The EBSD exhibited pronounced misorientation gradients in the areas adjacent to pre-existing boundaries,and severe fragmentation into subgrains.At larger strains,the density of subgrain boundaries declined due to the massive progress of discontinuous dynamic recrystallization(DDRX).TEM investigations confirmed the emergence of globular Mg_(5)Gd-type nano-particles exclusively within the DRXed areas through dynamic precipitation,and the precipitation of nano-sized β'-phase,mainly within the larger deformed grains.Basal texture components of“type-Ⅰ”and“type-Ⅱ”were identified following 6 SSE passes.In the former case,the basal planes rearranged parallel to the shear planes with their poles aligned along the normal direction(ND)as a result of the activity of the basal slip system.In contrast,in the latter scenario,the basal poles were parallel to the transverse direction(TD)due to the 90°rotation of the workpiece between consecutive passes.The results of shear punch testing(SPT)indicated an increase in the shear strength,as the number of passes in SSE increased from 1 to 6.The improved mechanical response of the alloys after SSE was ascribed to various strengthening mechanisms,including the influence of low-angle grain boundaries(LAGBs),precipitation hardening and grain boundary strengthening.展开更多
Uranium–molybdenum(U–Mo) alloys are critical for nuclear power generation and propulsion because of their superior thermal conductivity, irradiation stability, and anti-swelling properties. This study explores the p...Uranium–molybdenum(U–Mo) alloys are critical for nuclear power generation and propulsion because of their superior thermal conductivity, irradiation stability, and anti-swelling properties. This study explores the plastic deformation mechanisms of γ-phase U–Mo alloys using molecular dynamics(MD) simulations. In the slip model, the generalized stacking fault energy(GSFE) and the modified Peierls–Nabarro(P–N) model are used to determine the competitive relationships among different slip systems. In the twinning model, the generalized plane fault energy(GPFE) is assessed to evaluate the competition between slip and twinning. The findings reveal that among the three slip systems, the {110}<111>slip system is preferentially activated, while in the {112}<111> system, twinning is favored over slip, as confirmed by MD tensile simulations conducted in various directions. Additionally, the impact of Mo content on deformation behavior is emphasized. Insights are provided for optimizing process conditions to avoid γ → α′′ transitions, thereby maintaining a higher proportion of γ-phase U–Mo alloys for practical applications.展开更多
Laminated metal composites(LMCs)have widespread application prospects and are set to become indispensable in addressing modern engineering challenges owing to their capability of leveraging the synergy between differe...Laminated metal composites(LMCs)have widespread application prospects and are set to become indispensable in addressing modern engineering challenges owing to their capability of leveraging the synergy between different metals and tailoring performance by flexibly regulating the layered configuration.The plastic forming process,as a promising advanced manufacturing technology,has been increasingly adopted for the fabrication of LMC components due to its advantages of high material utilization rate,high production efficiency,and excellent mechanical properties of the product.This review delved into the research progress on the plastic-forming process of LMCs,including rolling,extrusion,spinning,etc.It outlined the forming principles,unique characteristics,bonding mechanisms,and the influence of key process parameters on deformation,microstructure,and property.This review focused on the heterogeneous deformation and interfacial regulation of LMCs,providing insights into the mechanisms of heterogeneous deformation,damage and fracture,and formation mechanisms of intermetallic compounds.It also delineated the experimental characterization and numerical modeling methods to elucidate the heterogeneous deformation behavior,as well as the approaches to evaluating and enhancing the performance of LMCs.Finally,the challenges and prospects of manufacturing high-performance LMCs by plastic forming process are orchestrated.展开更多
A new dimensionless number is proposed for dynamic plastic deformation analysis of clamped circular plates under underwater explosion loads by introducing dimensional analysis method to the basic dynamical governing e...A new dimensionless number is proposed for dynamic plastic deformation analysis of clamped circular plates under underwater explosion loads by introducing dimensional analysis method to the basic dynamical governing equations of circular plates.The relation between dimensionless final plastic deformation of circular plates and the new dimensionless number is established based on massive underwater explosion test data.Meanwhile,comparative analysis was discussed with two other published dimensionless parameters which indicated the new dimensionless number proposed in this paper is more effective and extensive to predict the dynamic plastic response of circular plates under underwater explosion condition.展开更多
Microstructure topology evolution during severe plastic deformation(SPD)is crucial for understanding and optimising the mechanical properties of metallic materials,though its prediction remains challenging.Herein,we c...Microstructure topology evolution during severe plastic deformation(SPD)is crucial for understanding and optimising the mechanical properties of metallic materials,though its prediction remains challenging.Herein,we combine discrete cell complexes(DCC),a fully discrete algebraic topology model-with finite element analysis(FEA)to simulate and analyse the microstructure topology of pure copper under SPD.Using DCC,we model the evolution of microstructure topology characterised by Betti numbers(β_(0),β_(1),β_(2))and Euler characteristic(χ).This captures key changes in GBNs and topological features within representative volume elements(RVEs)containing several hundred grains during SPD-induced recrystallisation.As SPD cycles increase,high-angle grain boundaries(HAGBs)progressively form.Topological analysis reveals an overall decrease in β_(0)values,indicating fewer isolated HAGB substructures,while β_(2) values show a steady upward trend,highlighting new grain formation.Leveraging DCC-derived RVE topology and FEA-generated plastic strain data,we directly simulate the evolution and spatial distribution of microstructure topology and HAGB fraction in a copper tube undergoing cyclic parallel tube channel angular pressing(PTCAP),a representative SPD technique.Within the tube,the HAGB fraction continuously increases with PTCAP cycles,reflecting the microstructure’s gradual transition from subgrains to fully-formed grains.Analysis of Betti number distribution and evolution reveals the microstructural reconstruction mechanism underpinning this subgrain to grain transition during PTCAP.We further demonstrate the significant influence of spatially non-uniform plastic strain distribution on microstructure reconstruction kinetics.This study demonstrates a feasible approach for simulating microstructure topology evolution of metals processed by cyclic SPD via the integration of DCC and FEA.展开更多
Ti-2Al-2.5Zr is widely used in piping and structural support applications,however,the rolling forming process results in anisotropic deformation during service.This behavior has implications for the manu-facturing pro...Ti-2Al-2.5Zr is widely used in piping and structural support applications,however,the rolling forming process results in anisotropic deformation during service.This behavior has implications for the manu-facturing processes and structural safety assessments in engineering applications.In this study,the plas-tic anisotropic deformation behavior of a rolled Ti-2Al-2.5Zr plate was investigated using uniaxial tensile tests along the transverse,normal,and 45°directions.Acoustic emission,electron backscatter diffraction,and scanning electron microscopy methods were used to investigate dislocation slip and twinning mech-anisms.The results indicated that different microscopic deformation mechanisms caused the significant macroscopic anisotropy of Ti-2Al-2.5Zr.The primary mechanisms involved were prismaticslip,pyra-midal<c+a>slip,and{10-12}extension twinning.The stress direction determined the influence of each of these mechanisms during the yielding and plastic deformation phases.Application of the visco-plastic self-consistent model established the relationship between the macroscopic mechanical responses and microscopic deformation mechanisms.It was revealed that Ti-2Al-2.5Zr achieved its optimum strength when the initial texture aligned most of the grain c-axis at angles ranging from 30°to 50°relative to the deformation direction.This finding provides a direction for the texture design of Ti-2Al-2.5Zr in engineer-ing materials.展开更多
To elucidate the mechanisms of regulating the microstructure uniformity in 7050 aluminum forgings through surface cumulative plastic deformation(SCPD),the microstructure under different solution treatments was investi...To elucidate the mechanisms of regulating the microstructure uniformity in 7050 aluminum forgings through surface cumulative plastic deformation(SCPD),the microstructure under different solution treatments was investigated using metallographic observation(OM),electron backscatter diffraction(EBSD),transmission electron microscopy(TEM),and X-ray diffraction(XRD).The findings demonstrate that the most uniform microstructure in the forgings is achieved with a solution treatment at 470℃for 30 min.The SCPD process generates a significant number of needle-shaped precipitates,resulting in a higher dislocation density and stored energy.Solution treatments alleviate the pinning effect of second-phase particles and facilitate static recrystallization(SRX)in forgings,leading to a reduction in grain size.Additionally,mechanical testing results demonstrate 7%−13%increase in tensile strength and more uniform elongation of the forgings in different directions.展开更多
The phase volume fraction has an important role in the match of the strength and plasticity of dual phase steel.The different bainite contents(18–53 vol.%)in polygonal ferrite and bainite(PF+B)dual phase steel were o...The phase volume fraction has an important role in the match of the strength and plasticity of dual phase steel.The different bainite contents(18–53 vol.%)in polygonal ferrite and bainite(PF+B)dual phase steel were obtained by controlling the relaxation finish temperature during the rolling process.The effect of bainite volume fraction on the tensile deformability was systematically investigated via experiments and crystal plasticity finite element model(CPFEM)simulation.The experimental results showed that the steel showed optimal strain hardenability and strength–plasticity matching when the bainite reached 35%.The 3D-CPFEM models with the same grain size and texture characters were established to clarify the influence of stress/strain distribution on PF+B dual phase steel with different bainite contents.The simulation results indicated that an appropriate increase in the bainite content(18%–35%)did not affect the interphase strain difference,but increased the stress distribution in both phases,as a result of enhancing the coordinated deformability of two phases and improving the strength–plasticity matching.When the bainite content increased to 53%,the stress/strain difference between the two phases was greatly increased,and plastic damage between the two phases was caused by the reduction of the coordinated deformability.展开更多
The advent of coarse-grain superplasticity has provided a pathway for novel applications in material forming.This article investigated the underlying deformation mechanisms that enabled achieving superplastic elongati...The advent of coarse-grain superplasticity has provided a pathway for novel applications in material forming.This article investigated the underlying deformation mechanisms that enabled achieving superplastic elongation exceeding 230%in a coarse-grained Ni-Co-based superalloy.The deformed microstructure and fractographic characteristics of the alloy were examined utilizing optical microscopy(OM),scanning electron microscopy(SEM),and electron backscatter diffraction(EBSD).The results of the analysis revealed that below 1100℃,the process of dynamic recrystallization(DRX)occurred at a sluggish rate,resulting in low plasticity and the initiation of severe cracks.Complete DRX occurred when the deformation temperature exceeded 1100℃,leading to a more uniformly deformed microstructure,reduced crack initiation,and enhanced ductility demonstrated by elongation to failure surpassing 230%.The augmented occurrence of the DRX facilitated prolonged plastic-forming periods,which delayed fracture propagation and promoted the deformation flow within the alloy,thereby transitioning the fracture behavior from intergranular-brittle at 1050℃to ductile intergranular at 1140℃.At this temperature,the deformation was predominantly governed by the discontinuous-DRX(DDRX)mechanism and grain growth,facilitated by the formation of twin boundaries.展开更多
A new type of extruded nickel-based powder metallurgy(P/M)superalloy was subjected to isothermal compression and tensile experiments to explore its superplasticity.Based on the compression flow curves,the hot working ...A new type of extruded nickel-based powder metallurgy(P/M)superalloy was subjected to isothermal compression and tensile experiments to explore its superplasticity.Based on the compression flow curves,the hot working maps of strain rate sensitivity index(m)were established at various strain levels.When compressing at1020-1110℃,in the strain rate range of 0.001-0.01 s^(-1),the m value was always greater than 0.3,indicating that the superalloy exhibited superplasticity in this deformation region.The tensile results showed that the superalloy exhibited excellent superplasticity under the conditions of 1050℃/0.01 s^(-1),1080℃/0.01 s^(-1)and 1110℃/0.001 s^(-1),with elongation after fracture reaching up to 1011%,1038%and951%,respectively.At low-temperature conditions and hightemperature/low strain rate conditions,both continuous dynamic recrystallization(CDRX)and discontinuous dynamic recrystallization(DDRX)were activated.As the deformation temperature increased,theγphases gradually dissolved into the matrix,and the primaryγ'phase changed from irregular shape to spherical or near-spherical shape.The interaction of theγ'phase with the dislocation promoted dynamic recrystallization(DRX)nucleation and thus slowed down the grain growth rate,which was essential for the superplastic deformation of the alloy.展开更多
Experiments and visco-plastic self-consistent (VPSC) simulations were used to quantify the amount of twinning and the relationship to stress?strain behavior in a textured Mg?3Al?1Zn plate. Two different compression di...Experiments and visco-plastic self-consistent (VPSC) simulations were used to quantify the amount of twinning and the relationship to stress?strain behavior in a textured Mg?3Al?1Zn plate. Two different compression directions were utilized to favor{1012} extension or{1011} compression twinning.{1012} twins nucleate at the beginning of plastic deformation and grow to consume the parent grains completely. During compression along the normal direction,{1011} twinning and{1011}?{1012} double twinning start at strain of 0.05, and the number of twins increases until rupture, above strain of 0.15.{1011} and{1011}?{1012} twinning also occur during compression along the transverse direction, start at strain of 0.06 and then multiply in grains totally reoriented by{1012} twins. Using suitable parameters, the VPSC model can accurately predict the occurrence of extension, compression and double-twinning as well as the flow stresses and deformed textures. According to VPSC simulations, twinning and slip have the same latent hardening parameters.展开更多
Based on the local canning compression,severe plastic deformation（SPD） is able to lead to the almost complete amorphous nickel-titanium shape memory alloy（NiTi SMA）,in which a small amount of retained nanocrystall...Based on the local canning compression,severe plastic deformation（SPD） is able to lead to the almost complete amorphous nickel-titanium shape memory alloy（NiTi SMA）,in which a small amount of retained nanocrystalline phase is embedded in the amorphous matrix.Crystallization of amorphous NiTi alloy annealed at 573,723 and 873 K was investigated,respectively.The crystallization kinetics of the amorphous NiTi alloy can be mathematically described by the Johnson-MehlAvrami-Kolmogorov（JMAK） equation.NiTi SMA with a complete nanocrystalline phase is obtained in the case of annealing at 573 K and 723 K,where martensite phase transformation is suppressed due to the constraint of the grain boundaries.Crystallization of amorphous NiTi alloy at 873 K leads to the coarse-grained NiTi sample,where（001） martensite compound twin is observed at room temperature.It can be found that the martensitic twins preferentially nucleate at the grain boundary and they grow up towards the two different grains.SPD based on the local canning compression and subsequent annealing provides a new approach to obtain the nanocrystalline NiTi SMA.展开更多
On the multi-layer forging die used in daily life,stressed ring can strength the die structure within elastic deformation and the die material can be self-strengthened through uniform plastic deformation by autofretta...On the multi-layer forging die used in daily life,stressed ring can strength the die structure within elastic deformation and the die material can be self-strengthened through uniform plastic deformation by autofrettage effect,whereas the thermal effect generated during forging process can directly influence the stress state and dimension of the forging die in service.In this study,an analytical solution of the thermo-elastic-plastic deformation in the forging die is derived.The relationships between the radial and circumferential stresses and the temperature distribution,which are directly related to geometric parameters,material properties and working pressure,are determined.This helps to better understand the thermo-elastic-plastic deformation behavior of the die and design the combined forging die to achieve long service life and high accuracy product.展开更多
The effects of plastic deformation on precipitation behavior and tensile fracture behavior of Mg-10Gd-3Y-0.6Zr alloy were investigated.The results indicate that more precipitation cores can be provided by the crystal ...The effects of plastic deformation on precipitation behavior and tensile fracture behavior of Mg-10Gd-3Y-0.6Zr alloy were investigated.The results indicate that more precipitation cores can be provided by the crystal defects caused by the plastic deformation,as well as increasing the amount of β＇ phases,and the formation of precipitations at grain boundaries and interfaces between the twins and matrix.Because of an increase in precipitations,the dislocation slipping during deformation process is effectively hindered and the matrix is strengthened,especially for the 2% deformed alloy which can achieve a good combination of strength and ductility.With increasing the plastic deformation,the microcracks occur at the interface between grain boundary precipitations and matrix,and then propagate intergranularly.When intergranular fracture combines with the formation of smoothing facets on the fracture surface,the tensile properties decrease.展开更多
基金supported by the Distinguished Young Scholars of China(No.52025014)Natural Science Foundation of Zhejiang Province(No.LQ23E010002)Innovation 2025 Major Project of Ningbo(Nos.2022Z011 and 2023Z022).
文摘The recently established theory has built clear connections between hardness and toughness and electron structure involving both valence electron concentration(VEC)and core electron count(CEC)in transition metal nitride(TMN)ceramics.However,the underlying deformation mechanisms remain unclear.Herein,we conduct in-depth analysis on microstructure evolution during deformation of the high VEC-CEC solution TiMoN coatings having desired combination of high hardness and toughness.The effects of solid solution,preferred orientation linked with symbiotic compressive stress,grain size and dislocations are systematically discussed.We discover that numerous dislocations have been implanted into the nanocrystals of the TiMoN coating during the high-ionization arc deposition.Using two-beam bright-field imaging,we count the dislocation density and confirm occurrence of dislocation multiplication to form effective plastic deformation,which contributes to significant strain hardening,comparable to solid solution hardening,fine-grain hardening and compressive stress hardening.The improved dislocation activities also play a crucial role in enhancing the toughness by providing extra energy dissipation paths.This work gains new insights into the origins of mechanical properties of ceramic coatings and possibility to tune them via defects.
基金The authors gratefully appreciate financial support by Program of Shanghai Academic Research Leader(No.22XD1421600).
文摘The Mg-4Y-3RE(WE43)magnesium alloy possesses significant advantages such as high specific strength,excellent shock absorption,strong electromagnetic shielding capabilities and recyclability.However,its close-packed hexagonal structure leads to poor plasticity at room temperature,which limits its broader engineering applications.Therefore,superplastic forming at high temperatures is used to manufacture the components from this alloy.This study conducted tensile tests on hot-rolled WE43 rare-earth magnesium alloy with coarse grains at various temperatures and strain rates.The high-temperature superplastic properties were characterized,revealing the intrinsic mechanisms of thermal deformation behavior.The results indicate that the best superplasticity is achieved at 460℃.This is attributed to the smallest grain size,the weakest texture,and the relatively uniform distribution of the second phase at this temperature.The influence of strain rate on elongation at temperatures among 440℃∼500℃is not significant as the impact of strain rate is multifaceted.Meanwhile,the elongation can reach up to 367.7±3.7%at a strain rate of 0.01s^(−1),which exhibits the high strain rate superplasticity(HSRS).Under these conditions,the deformation of coarse-grained WE43 rare-earth magnesium alloy is controlled by grain boundary sliding(GBS)and solute drag dislocation creep.Furthermore,the GBS involves deformation coordination mechanisms such as grain boundary diffusion,lattice diffusion,dislocation climbing,and dynamic recrystallization accommodation mechanisms.
基金supported by the National Natural Science Foundation of China(Nos.U22A20121,52101283 and 52271243)the NSFC-RGC Joint Research Scheme(No.52361165619)+3 种基金The NSFC-RFBR Joint Research Scheme(No.82361138575)the Science and Technology Planning Project of Guangzhou(No.202201011454)the National Key R&D Program of China(Nos.2021YFC2400700 and 2021YFC2400704)the High-level Hospital Construction Project(No.KJ012019520).
文摘To date,nanostructuring through plastic deformation has rarely been reported in biodegradable zinc(Zn)based alloys that have great potential in load-bearing conditions.Here,typical high-strength Zn-Li-based alloys were subjected to SPD processes,including equal channel angular pressing(ECAP)and high-pressure torsion(HPT),to achieve nanostructured microstructures.The effects of SPD on the microstructures,mechanical properties,and corrosion behaviors were generally investigated.The two SPD routes resulted in totally different microstructures.ECAPed samples processed at 150℃ exhibited a complicated multilevel structure(nm toμm)with mixed Zn equiaxed grains and lamellar-like eutectoid regions(Zn+α-LiZn_(4)),and HPTed ones(25℃)possessed a fully dynamically recrystallized(DRXed)microstructure with an average grain size below 0.4μm.The tensile strength of the SPD samples could reach 500 MPa.Meanwhile,HPTed samples exhibited extraordinary fracture elongations higher than 100%,because of a different grain boundary sliding deformation mechanism.HPTed samples and ECAPed samples displayed different corrosion patterns,and the former exhibited a much higher corrosion rate in Hank's solution,possibly due to the accelerated corrosion at grain boundaries.In summary,SPD is an efficient way to refine the microstructure of biodegradable Zn-based alloys,possibly improving their performances and clinical applications.
基金supported by the National Key R&D Program of China(Grant No.2023YFB2408000)Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515010950)the National Natural Science Foundation of China(Grant No.12002192).
文摘Lithium metal batteries have been deemed one of the most promising candidates for new-generation batteries,used in mobile devices,electric vehicles,energy storage,etc.However,due to the volume change of active materials and external pressure,the electrode materials and interfaces between battery components have high stresses during the cycling process,resulting in large deformation of the lithium metal anode.Herein,we derive insights into the mechanical behaviors of polycrystalline lithium metal.Specifically,the mechanical properties of lithium metal containing Li_(7-x)La_(3)Zr_(2-x)Ta_(x)O_(12)(x=0.2-0.7)(LLZTO)solid-state electrolyte impurities are experimentally investigated.It is found that its strength is governed by impurity content and impurity particle size.In addition,we explore the Hall-Petch and inverse Hall-Petch effects of nanocrystalline lithium through atomic-scale simulations,revealing the plastic deformation mechanism in polycrystalline lithium metal.This fundamental study sheds light on the impurity-modulated mechanical properties and plastic deformation mechanism of polycrystalline lithium metal.
基金Project (50971087) supported by the National Natural Science Foundation of ChinaProject (BK2012715) supported by the Basic Research Program (Natural Science Foundation) of Jiangsu Province, China+1 种基金Project (10371800) supported by the Research Council of Norway under the NEW Light (NEWLIGHT) Metals of the Strategic Area (SA) MaterialsProject (11JDG070) supported by the Senior Talent Research Foundation of Jiangsu University, China
文摘In order to explore the exact nature of deformation defects previously observed in nanostructured Al-Mg alloys subjected to severe plastic deformation, a more thorough examination of the radiation effect on the formation of the planar defects in the high pressure torsion （HPT） alloys was conducted using high-resolution transmission electron microscopy （HRTEM）. The results show that high density defects in the HRTEM images disappear completely when these images are exposed under the electron beam for some duration of time. At the same time, lattice defects are never observed within no-defect areas even when the beam-exposure increases to the degree that holes appear in the areas. Therefore, it is confirmed that the planar defects observed in the HPT alloys mainly result from the significant plastic deformation and are not due to the radiation effect during HRTEM observation.
基金supported by the National Research Foundation grant funded by the Korean government(No,2023R1A2C2007190,RS-2024-00398068)partially funded by the Natural Science Foundation of Shandong Province,China(No.ZR2022QE206).
文摘The effects of solid solution on the deformation behavior of binary Mg-xZn(x=0,1,2 wt%)alloys featuring a designated texture that enables extension twinning under tension parallel to the basal pole in most grains,were investigated using in-situ neutron diffraction and the EVPSC-TDT model.Neutron diffraction was used to quantitatively track grain-level lattice strains and diffraction intensity changes(related to mechanical twinning)in differently oriented grains of each alloy during cyclic tensile/compressive loadings.These measurements were accurately captured by the model.The stress-strain curves of Mg-1 wt%Zn and Mg-2 wt%Zn alloys show as-expected solid solution strengthening from the addition of Zn compared to pure Mg.The macroscopic yielding and hardening behaviors are explained by alternating slip and twinning modes as calculated by the model.The solid solution's influence on individual deformation modes,including basal〈a〉slip,prismatic〈a〉slip,and extension twinning,was then quantitatively assessed in terms of activity,yielding behavior,and hardening response by combining neutron diffraction results with crystal plasticity predictions.The Mg-1 wt%Zn alloy displays distinct yielding and hardening behavior due to solid solution softening of prismatic〈a〉slip.Additionally,the dependence of extension twinning,in terms of the twinning volume fraction,on Zn content exhibits opposite trends under tensile and compressive loadings.
基金financial support of PX Group to their laboratory
文摘An extruded Mg-Gd-Y-Ag alloy was subjected to simple shear extrusion(SSE)at 280℃ to obtain a refined microstructure,with a focus on examining microstructural evolutions through detailed EBSD analysis and TEM.The EBSD results revealed that the microstructures at the early stages of deformation contained large deformed grains with a significant fraction of low angle grain boundaries developed through dynamic recovery.Continuous dynamic recrystallization(CDRX)was dominant as deformation proceeded.Two kinds of CDRX grains were recognized considering their locations;“GB-type”grains,which formed in the vicinity of the pre-existing boundaries of the deformed grains,and“Core-type”grains,emerging within the interior areas.The EBSD exhibited pronounced misorientation gradients in the areas adjacent to pre-existing boundaries,and severe fragmentation into subgrains.At larger strains,the density of subgrain boundaries declined due to the massive progress of discontinuous dynamic recrystallization(DDRX).TEM investigations confirmed the emergence of globular Mg_(5)Gd-type nano-particles exclusively within the DRXed areas through dynamic precipitation,and the precipitation of nano-sized β'-phase,mainly within the larger deformed grains.Basal texture components of“type-Ⅰ”and“type-Ⅱ”were identified following 6 SSE passes.In the former case,the basal planes rearranged parallel to the shear planes with their poles aligned along the normal direction(ND)as a result of the activity of the basal slip system.In contrast,in the latter scenario,the basal poles were parallel to the transverse direction(TD)due to the 90°rotation of the workpiece between consecutive passes.The results of shear punch testing(SPT)indicated an increase in the shear strength,as the number of passes in SSE increased from 1 to 6.The improved mechanical response of the alloys after SSE was ascribed to various strengthening mechanisms,including the influence of low-angle grain boundaries(LAGBs),precipitation hardening and grain boundary strengthening.
基金Project supported by the National Natural Science Foundation of China (Grant No. 52271105)。
文摘Uranium–molybdenum(U–Mo) alloys are critical for nuclear power generation and propulsion because of their superior thermal conductivity, irradiation stability, and anti-swelling properties. This study explores the plastic deformation mechanisms of γ-phase U–Mo alloys using molecular dynamics(MD) simulations. In the slip model, the generalized stacking fault energy(GSFE) and the modified Peierls–Nabarro(P–N) model are used to determine the competitive relationships among different slip systems. In the twinning model, the generalized plane fault energy(GPFE) is assessed to evaluate the competition between slip and twinning. The findings reveal that among the three slip systems, the {110}<111>slip system is preferentially activated, while in the {112}<111> system, twinning is favored over slip, as confirmed by MD tensile simulations conducted in various directions. Additionally, the impact of Mo content on deformation behavior is emphasized. Insights are provided for optimizing process conditions to avoid γ → α′′ transitions, thereby maintaining a higher proportion of γ-phase U–Mo alloys for practical applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.52305361,52105337,52475354,and 52090043)the BK21 Four program(SNU Materials Education/Research Division for Creative Global Leaders)+1 种基金the China Postdoctoral Science Foundation(Grant No.2023M741245),and the National Key Research and Development Program of China(Grant No.2022YFB3706903)support from the Ko-rean Ministry of Trade,Industry and Energy(MOTIE,Korea)(Grant No.20022438).
文摘Laminated metal composites(LMCs)have widespread application prospects and are set to become indispensable in addressing modern engineering challenges owing to their capability of leveraging the synergy between different metals and tailoring performance by flexibly regulating the layered configuration.The plastic forming process,as a promising advanced manufacturing technology,has been increasingly adopted for the fabrication of LMC components due to its advantages of high material utilization rate,high production efficiency,and excellent mechanical properties of the product.This review delved into the research progress on the plastic-forming process of LMCs,including rolling,extrusion,spinning,etc.It outlined the forming principles,unique characteristics,bonding mechanisms,and the influence of key process parameters on deformation,microstructure,and property.This review focused on the heterogeneous deformation and interfacial regulation of LMCs,providing insights into the mechanisms of heterogeneous deformation,damage and fracture,and formation mechanisms of intermetallic compounds.It also delineated the experimental characterization and numerical modeling methods to elucidate the heterogeneous deformation behavior,as well as the approaches to evaluating and enhancing the performance of LMCs.Finally,the challenges and prospects of manufacturing high-performance LMCs by plastic forming process are orchestrated.
基金supported by the National Natural Science Foundation of China(12402444)。
文摘A new dimensionless number is proposed for dynamic plastic deformation analysis of clamped circular plates under underwater explosion loads by introducing dimensional analysis method to the basic dynamical governing equations of circular plates.The relation between dimensionless final plastic deformation of circular plates and the new dimensionless number is established based on massive underwater explosion test data.Meanwhile,comparative analysis was discussed with two other published dimensionless parameters which indicated the new dimensionless number proposed in this paper is more effective and extensive to predict the dynamic plastic response of circular plates under underwater explosion condition.
基金support from Outstanding Youth Fund of Jiangsu Province(BK20240077)Key Project(Provincial-Municipal Joint)of Jiangsu Province(BK20243044)+2 种基金Fundamental Research Funds for the Central Universities(NE2024001)National Youth Talents Programof Chinaa project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Microstructure topology evolution during severe plastic deformation(SPD)is crucial for understanding and optimising the mechanical properties of metallic materials,though its prediction remains challenging.Herein,we combine discrete cell complexes(DCC),a fully discrete algebraic topology model-with finite element analysis(FEA)to simulate and analyse the microstructure topology of pure copper under SPD.Using DCC,we model the evolution of microstructure topology characterised by Betti numbers(β_(0),β_(1),β_(2))and Euler characteristic(χ).This captures key changes in GBNs and topological features within representative volume elements(RVEs)containing several hundred grains during SPD-induced recrystallisation.As SPD cycles increase,high-angle grain boundaries(HAGBs)progressively form.Topological analysis reveals an overall decrease in β_(0)values,indicating fewer isolated HAGB substructures,while β_(2) values show a steady upward trend,highlighting new grain formation.Leveraging DCC-derived RVE topology and FEA-generated plastic strain data,we directly simulate the evolution and spatial distribution of microstructure topology and HAGB fraction in a copper tube undergoing cyclic parallel tube channel angular pressing(PTCAP),a representative SPD technique.Within the tube,the HAGB fraction continuously increases with PTCAP cycles,reflecting the microstructure’s gradual transition from subgrains to fully-formed grains.Analysis of Betti number distribution and evolution reveals the microstructural reconstruction mechanism underpinning this subgrain to grain transition during PTCAP.We further demonstrate the significant influence of spatially non-uniform plastic strain distribution on microstructure reconstruction kinetics.This study demonstrates a feasible approach for simulating microstructure topology evolution of metals processed by cyclic SPD via the integration of DCC and FEA.
基金support from the National Key R&D Program of China(No.2020YFA0405901)the National Natural Science Foundation of China(Nos.52375155 and 51875398)+1 种基金the Science and Technology on Reactor Fuel and Materials Laboratory(No.6142A06040202)the Nuclear Power Institute of China.
文摘Ti-2Al-2.5Zr is widely used in piping and structural support applications,however,the rolling forming process results in anisotropic deformation during service.This behavior has implications for the manu-facturing processes and structural safety assessments in engineering applications.In this study,the plas-tic anisotropic deformation behavior of a rolled Ti-2Al-2.5Zr plate was investigated using uniaxial tensile tests along the transverse,normal,and 45°directions.Acoustic emission,electron backscatter diffraction,and scanning electron microscopy methods were used to investigate dislocation slip and twinning mech-anisms.The results indicated that different microscopic deformation mechanisms caused the significant macroscopic anisotropy of Ti-2Al-2.5Zr.The primary mechanisms involved were prismaticslip,pyra-midal<c+a>slip,and{10-12}extension twinning.The stress direction determined the influence of each of these mechanisms during the yielding and plastic deformation phases.Application of the visco-plastic self-consistent model established the relationship between the macroscopic mechanical responses and microscopic deformation mechanisms.It was revealed that Ti-2Al-2.5Zr achieved its optimum strength when the initial texture aligned most of the grain c-axis at angles ranging from 30°to 50°relative to the deformation direction.This finding provides a direction for the texture design of Ti-2Al-2.5Zr in engineer-ing materials.
基金supported by the Natural Science Foundation of Hebei Province,China(Nos.E2019203075,E2021203059)the National Natural Science Foundation of China(No.52171018)+1 种基金Top Young Talents Project of the Education Department of Hebei Province,China(No.BJ2019001)the Open Research Fund of State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South University,China(No.Kfkt2023-09).
文摘To elucidate the mechanisms of regulating the microstructure uniformity in 7050 aluminum forgings through surface cumulative plastic deformation(SCPD),the microstructure under different solution treatments was investigated using metallographic observation(OM),electron backscatter diffraction(EBSD),transmission electron microscopy(TEM),and X-ray diffraction(XRD).The findings demonstrate that the most uniform microstructure in the forgings is achieved with a solution treatment at 470℃for 30 min.The SCPD process generates a significant number of needle-shaped precipitates,resulting in a higher dislocation density and stored energy.Solution treatments alleviate the pinning effect of second-phase particles and facilitate static recrystallization(SRX)in forgings,leading to a reduction in grain size.Additionally,mechanical testing results demonstrate 7%−13%increase in tensile strength and more uniform elongation of the forgings in different directions.
基金supported by the Project of Liaoning Marine Economic Development(Development of high strength pipeline steel for submarine oil and gas transmission)State Key Laboratory of Metal Material for Marine Equipment and Application Funding(No.SKLMEA-K202205).
文摘The phase volume fraction has an important role in the match of the strength and plasticity of dual phase steel.The different bainite contents(18–53 vol.%)in polygonal ferrite and bainite(PF+B)dual phase steel were obtained by controlling the relaxation finish temperature during the rolling process.The effect of bainite volume fraction on the tensile deformability was systematically investigated via experiments and crystal plasticity finite element model(CPFEM)simulation.The experimental results showed that the steel showed optimal strain hardenability and strength–plasticity matching when the bainite reached 35%.The 3D-CPFEM models with the same grain size and texture characters were established to clarify the influence of stress/strain distribution on PF+B dual phase steel with different bainite contents.The simulation results indicated that an appropriate increase in the bainite content(18%–35%)did not affect the interphase strain difference,but increased the stress distribution in both phases,as a result of enhancing the coordinated deformability of two phases and improving the strength–plasticity matching.When the bainite content increased to 53%,the stress/strain difference between the two phases was greatly increased,and plastic damage between the two phases was caused by the reduction of the coordinated deformability.
基金financially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDC0140000)the National Science and Technology Major Project(No.J2019-VI-0006-0120)+3 种基金the Science and Technology Major Project of Liaoning Province(No.2024JH1/11700037)the Youth Innovation Promotion Association,CAS(No.2023202)the Natural Science Foundation Project of Liaoning Province(No.2023-MS-024)the National Science and Technology Major Project(No.2024ZD0600600).
文摘The advent of coarse-grain superplasticity has provided a pathway for novel applications in material forming.This article investigated the underlying deformation mechanisms that enabled achieving superplastic elongation exceeding 230%in a coarse-grained Ni-Co-based superalloy.The deformed microstructure and fractographic characteristics of the alloy were examined utilizing optical microscopy(OM),scanning electron microscopy(SEM),and electron backscatter diffraction(EBSD).The results of the analysis revealed that below 1100℃,the process of dynamic recrystallization(DRX)occurred at a sluggish rate,resulting in low plasticity and the initiation of severe cracks.Complete DRX occurred when the deformation temperature exceeded 1100℃,leading to a more uniformly deformed microstructure,reduced crack initiation,and enhanced ductility demonstrated by elongation to failure surpassing 230%.The augmented occurrence of the DRX facilitated prolonged plastic-forming periods,which delayed fracture propagation and promoted the deformation flow within the alloy,thereby transitioning the fracture behavior from intergranular-brittle at 1050℃to ductile intergranular at 1140℃.At this temperature,the deformation was predominantly governed by the discontinuous-DRX(DDRX)mechanism and grain growth,facilitated by the formation of twin boundaries.
基金financially supported by Shandong Provincial Natural Science Foundation of China(Nos.ZR2024JQ020 and ZR2021QE102)Taishan Scholars Program of Shandong Province(Nos.tsqn202211115 and tsqn202306162)+2 种基金Yantai high-end talent introduction"Double Hundred Plan"(2021)the Science Foundation Program for Distinguished Young Scholars of Shandong(Overseas)(No.2022HWYQ-084)the Talent Training Program for Shandong Province Higher Educational Youth Innovative Teams(2021)
文摘A new type of extruded nickel-based powder metallurgy(P/M)superalloy was subjected to isothermal compression and tensile experiments to explore its superplasticity.Based on the compression flow curves,the hot working maps of strain rate sensitivity index(m)were established at various strain levels.When compressing at1020-1110℃,in the strain rate range of 0.001-0.01 s^(-1),the m value was always greater than 0.3,indicating that the superalloy exhibited superplasticity in this deformation region.The tensile results showed that the superalloy exhibited excellent superplasticity under the conditions of 1050℃/0.01 s^(-1),1080℃/0.01 s^(-1)and 1110℃/0.001 s^(-1),with elongation after fracture reaching up to 1011%,1038%and951%,respectively.At low-temperature conditions and hightemperature/low strain rate conditions,both continuous dynamic recrystallization(CDRX)and discontinuous dynamic recrystallization(DDRX)were activated.As the deformation temperature increased,theγphases gradually dissolved into the matrix,and the primaryγ'phase changed from irregular shape to spherical or near-spherical shape.The interaction of theγ'phase with the dislocation promoted dynamic recrystallization(DRX)nucleation and thus slowed down the grain growth rate,which was essential for the superplastic deformation of the alloy.
基金Project(2013CB632204)supported by the National Basic Research Program of ChinaProject(51350110332)supported by the National Natural Science Foundation of China
文摘Experiments and visco-plastic self-consistent (VPSC) simulations were used to quantify the amount of twinning and the relationship to stress?strain behavior in a textured Mg?3Al?1Zn plate. Two different compression directions were utilized to favor{1012} extension or{1011} compression twinning.{1012} twins nucleate at the beginning of plastic deformation and grow to consume the parent grains completely. During compression along the normal direction,{1011} twinning and{1011}?{1012} double twinning start at strain of 0.05, and the number of twins increases until rupture, above strain of 0.15.{1011} and{1011}?{1012} twinning also occur during compression along the transverse direction, start at strain of 0.06 and then multiply in grains totally reoriented by{1012} twins. Using suitable parameters, the VPSC model can accurately predict the occurrence of extension, compression and double-twinning as well as the flow stresses and deformed textures. According to VPSC simulations, twinning and slip have the same latent hardening parameters.
基金Project (51071056) supported by the National Natural Science Foundation of ChinaProject (HEUCF201317002) supported by the Fundamental Research Funds for the Central Universities of China
文摘Based on the local canning compression,severe plastic deformation（SPD） is able to lead to the almost complete amorphous nickel-titanium shape memory alloy（NiTi SMA）,in which a small amount of retained nanocrystalline phase is embedded in the amorphous matrix.Crystallization of amorphous NiTi alloy annealed at 573,723 and 873 K was investigated,respectively.The crystallization kinetics of the amorphous NiTi alloy can be mathematically described by the Johnson-MehlAvrami-Kolmogorov（JMAK） equation.NiTi SMA with a complete nanocrystalline phase is obtained in the case of annealing at 573 K and 723 K,where martensite phase transformation is suppressed due to the constraint of the grain boundaries.Crystallization of amorphous NiTi alloy at 873 K leads to the coarse-grained NiTi sample,where（001） martensite compound twin is observed at room temperature.It can be found that the martensitic twins preferentially nucleate at the grain boundary and they grow up towards the two different grains.SPD based on the local canning compression and subsequent annealing provides a new approach to obtain the nanocrystalline NiTi SMA.
基金National Natural Science Foundation of China(No.51875348)。
文摘On the multi-layer forging die used in daily life,stressed ring can strength the die structure within elastic deformation and the die material can be self-strengthened through uniform plastic deformation by autofrettage effect,whereas the thermal effect generated during forging process can directly influence the stress state and dimension of the forging die in service.In this study,an analytical solution of the thermo-elastic-plastic deformation in the forging die is derived.The relationships between the radial and circumferential stresses and the temperature distribution,which are directly related to geometric parameters,material properties and working pressure,are determined.This helps to better understand the thermo-elastic-plastic deformation behavior of the die and design the combined forging die to achieve long service life and high accuracy product.
基金Project(IRT0713) supported by the Program for Changjiang Scholars and Innovative Research Team in Chinese UniversityProjects(2007CB613701,2007CB613702) supported by the National Basic Research Program of China
文摘The effects of plastic deformation on precipitation behavior and tensile fracture behavior of Mg-10Gd-3Y-0.6Zr alloy were investigated.The results indicate that more precipitation cores can be provided by the crystal defects caused by the plastic deformation,as well as increasing the amount of β＇ phases,and the formation of precipitations at grain boundaries and interfaces between the twins and matrix.Because of an increase in precipitations,the dislocation slipping during deformation process is effectively hindered and the matrix is strengthened,especially for the 2% deformed alloy which can achieve a good combination of strength and ductility.With increasing the plastic deformation,the microcracks occur at the interface between grain boundary precipitations and matrix,and then propagate intergranularly.When intergranular fracture combines with the formation of smoothing facets on the fracture surface,the tensile properties decrease.
