The formation mechanism for the body-centered cubic structure of cluster is proposed and its total energy curve is calculated by the method of a Modified Arrangement Channel Quantum Mechanics. The energy is the funct...The formation mechanism for the body-centered cubic structure of cluster is proposed and its total energy curve is calculated by the method of a Modified Arrangement Channel Quantum Mechanics. The energy is the function of separation R between the nuclei at the center and an apex of the body-centered cubic structure. The result of the calculation shows that the curve has a minimal energy . The binding energy of with respect to was calculated to be 0.8857 a.u. This means that the cluster ofmay be formed in the body-centered cubic structure of .展开更多
Body-centered tetragonal C4 （bct C4） is a new form of crystalline spa carbon, which is found to be transparent, dynamically stable at zero pressure and more stable than graphite beyond 18.6 GPa. Symmetry analysis of...Body-centered tetragonal C4 （bct C4） is a new form of crystalline spa carbon, which is found to be transparent, dynamically stable at zero pressure and more stable than graphite beyond 18.6 GPa. Symmetry analysis of the vibrational modes of bct C4 at Brillouin zone center is performed, Raman and infrared active modes are identified. The analysis results show that, different from cubic diamond and hexagonal diamond, there is an infrared active mode in bct C4. Based on first-principle method within the local density approximation, vibrational frequencies, Born effective charge tensors, and infrared absorption intensity of bct C4 are obtained. The vibrational modes of bct C4 are presented and compared with those of cubic diamond and hexagonal diamond in detail展开更多
Background: The roots of autism spectrum disorders become evident in first attunement mechanisms between mother and child that allow a first level of mentalizing. Neurosciences and current developmental theories confi...Background: The roots of autism spectrum disorders become evident in first attunement mechanisms between mother and child that allow a first level of mentalizing. Neurosciences and current developmental theories confirm the existence of defensive mechanisms related to body and affectivity that psychodynamic theories had already highlighted. Reading child’s behavior not only by administering tests but also through careful clinical observations allows a better understanding of the communication and social difficulties present in autistic children. The identification of the zone of proximal development can promote a therapeutic intervention that respects the individuality of the child and the specificity of his relational approach to the world. Conclusion: The paper presents the theoretical principles of a body-centered therapy to promote the attunement processes necessary to activate cognitive resources.展开更多
The introduction of carbon interstitials into high-entropy alloys(HEAs)provides an effective way to improve their properties.However,all such HEA systems explored so far are limited to those with the face-centered-cub...The introduction of carbon interstitials into high-entropy alloys(HEAs)provides an effective way to improve their properties.However,all such HEA systems explored so far are limited to those with the face-centered-cubic(fcc)structure.Here we report the structural,mechanical and physical properties of the refractory(Nb_(0.375)Ta_(0.25)Mo_(0.125)W_(0.125)Re_(0.125))_(100−x)C_(x) HEAs over a wide x range of 0≤x≤20.It is found that,whereas the starting HEA(x=0)is composed of a major body-centered-cubic(bcc)phase with significant impurities,the bcc phase fraction increases with the C concentration and achieves almost 100%at x=20.Moreover,the increase of C content x results in an expansion of the bcc lattice,an enhancement of the microhardness,an increase in residual resistivity and a small variation of density of states at the Fermi level.All these features are consistent with the expectation that carbon atoms occupy the interstitial site.For x≥11.1,the X-ray photoelectron spectroscopy indicates the bond formation between the carbon and metal atoms,suggesting that some carbon atoms may also reside in the lattice site.In addition,a semiquantitative analysis shows that the enhanced mixing entropy caused by carbon addition plays a key role in stabilizing the(nearly)single solid-solution phase.Our study not only provides the first series of carbon interstitial HEAs with a bcc structure,but also helps to better understand the alloying behavior of carbon in refractory HEAs.展开更多
Submicron and nanostructured body-centered cubic(BCC) metals exhibit unusual mechanical performance compared to their bulk coarse-grained counterparts, including high yield strength and outstanding ductility. These pr...Submicron and nanostructured body-centered cubic(BCC) metals exhibit unusual mechanical performance compared to their bulk coarse-grained counterparts, including high yield strength and outstanding ductility. These properties are important for their applications in micro-, nano-and even atomic-scale devices as well as for their usages as components for enhancing the performances of structural materials. One aspect of the unusual mechanical properties of small-sized BCC metals is closely related to their dimensional confinement. Decreasing the dimensions of single crystalline metals or the grain sizes of polycrystalline metals contributes significantly to the strengthening of the small-sized BCC metals.In the last decade, significant progress has been achieved in understanding the plasticity and deformation behaviors of small-sized BCC metals. This paper aims to provide a comprehensive review on the current understanding of size effects on the plasticity and deformation mechanisms of small-sized BCC metals. The techniques used for in situ characterization of the deformation behavior and mechanical properties of small-sized samples are also presented.展开更多
High-entropy alloys greatly expand the alloy design range and offer new possibilities for improving material performance.Based on the worldwide research efforts in the last decade,the excellent mechanical properties a...High-entropy alloys greatly expand the alloy design range and offer new possibilities for improving material performance.Based on the worldwide research efforts in the last decade,the excellent mechanical properties and promising radiation and corrosion resistance of this group of materials have been demonstrated.High-entropy alloys with body-centered cubic(BCC)structures,especially refractory high-entropy alloys,are considered as promising materials for high-temperature applications in advanced nuclear reactors.However,the extreme reactor conditions including high temperature,high radiation damage,high stress,and complex corrosive environment require a comprehensive evaluation of the material properties for their actual service in nuclear reactors.This review summarizes the current progress on BCC high-entropy alloys from the aspects of neutron economy and activation,mechanical properties,high-temperature stability,radiation resistance,as well as corrosion resistance.Although the current development of BCC high-entropy alloys for nuclear applications is still at an early stage as the large design space of this group of alloys has not been fully explored,the current research findings provide a good basis for the understanding and prediction of material behaviors with different compositions and microstructures.Further in-depth understanding of the degradation mechanisms and characterization of material properties in response to conditions close to reactor environment are necessary.A critical down-selection of potential candidates is also crucial for further comprehensive evaluation and engineering validation.展开更多
Martensite is one of the most important structures determining the ability to tailor the performance of steel and several other engineering materials.In previous studies,the face-centered cubic(FCC)to hexag-onal close...Martensite is one of the most important structures determining the ability to tailor the performance of steel and several other engineering materials.In previous studies,the face-centered cubic(FCC)to hexag-onal close-packed(HCP)(or body-centered cubic(BCC))martensitic transformation and the FCC to body-centered tetragonal(BCT)(or BCC)martensitic transformation during deformation and quenching were widely investigated;these transformations usually improve the plasticity and strength of steel,respec-tively.In this work,detailed transmission electron microscopy(TEM)observations and electron diffraction pattern analyses of the BCT and BCC twins are performed along the[110],[131],and[¯153]zone axes.The transformation of BCT twins into BCC twins along the[131]zone axis is also analyzed through in situ heating during the TEM observations.The high-resolution TEM observations of mutually perpendicular BCT variants are consistent with the atomic arrangement obtained for the quenching pathway during the martensitic transformation.In addition,different orientation relationships between austenite and marten-site are explained in terms of the atomic migration occurring during the deformation pathway and the quenching pathway of the martensitic transformation.展开更多
In order to improve the discharge capacity and cyclic life of Mg-Co-based alloy, ternary Mg45M5Co50 （M=Pd, Zr） alloys were synthesized via mechanical alloying. TEM analysis demonstrates that these alloys all possess...In order to improve the discharge capacity and cyclic life of Mg-Co-based alloy, ternary Mg45M5Co50 （M=Pd, Zr） alloys were synthesized via mechanical alloying. TEM analysis demonstrates that these alloys all possess body-centered cubic （BCC） phase in nano-crystalline. Electrochemical experiments show that Mg45Zr5Co50 electrode exhibits the highest capacity （425 mA·h/g） among the Mg45M5Co50 （M=Mg, Pd, Zr） alloys. And Mg45Pd5Co50 electrode lifts not only the initial discharge capacity （379 mA·h/g）, but also the discharge kinetics, e.g., exchange current density and hydrogen diffusion ability from that of Mg50Co50. It could be concluded that the electrochemical performances were enhanced by substituting Zr and Pd for Mg in Mg-Co-based alloy.展开更多
Fe_(72.4)Co_(13.9)Cr_(10.4)Mn_(2.7)B_(0.34)high entropy steel was prepared by magnetron sputtering.The alloy exhibits a high yield strength of 2.92±0.36 GPa while achieving appreciable plasticity of 13.7±1.9...Fe_(72.4)Co_(13.9)Cr_(10.4)Mn_(2.7)B_(0.34)high entropy steel was prepared by magnetron sputtering.The alloy exhibits a high yield strength of 2.92±0.36 GPa while achieving appreciable plasticity of 13.7±1.9%at the ultimate compressive strength(3.37±0.36 GPa).The distribution of iron and chromium shows an un-usual,characteristic spinodal-like pattern at the nanometer scale,where compositions of Fe and Cr show strong anticorrelation and vary by as much as 20 at.%.The high strength is largely attributable to the compositional modulations,combined with fine grains with body-centered cubic(BCC)crystal structure,as well as grain boundary segregation of interstitial boron.The impressive plasticity is accommodated by the formation and operation of multiplanar,multicharacter dislocation slips,mediated by coherent in-terfaces,and controlled by shear bandings.The excellent strength-ductility combination is thus enabled by a range of distinctive strengthening mechanisms,rendering the new alloy a potential candidate for safety-critical,load-bearing structural applications.展开更多
Refractory multi-principal element alloys(RMPEAs)have garnered attention for their potential in high-temperature applications.Additive manufacturing(AM)provides opportunities to tailor RMPEAs’microstructures to enhan...Refractory multi-principal element alloys(RMPEAs)have garnered attention for their potential in high-temperature applications.Additive manufacturing(AM)provides opportunities to tailor RMPEAs’microstructures to enhance these properties.However,controlling defects and addressing the challenges posed by the complex thermal history during the AM process are crucial for optimizing RMPEAs’performance.This study aims to fabricate a high-quality oxygen-doped NbTiZr alloys using laser powder bed fusion and investigate their microstructure and mechanical properties.Our analysis reveals refined grain sizes and a periodic combination of fine near-equiaxed and columnar grain morphologies in the AM-fabricated alloy.Its substructure is characterized by the coexistence of loosely defined cellular dislocation networks and elemental segregation.Compared to its cast counterpart,the additively manufactured alloy exhibits a combination of high yield strength,excellent tensile ductility,and enhanced work hardening.These attributes make the AM-fabricated oxygen-doped NbTiZr alloy a promising candidate for applications required balanced mechanical properties.Understanding the specific effects of different crystal structures and deformation mechanisms is essential for optimizing AM processes to tailor the microstructure and achieve the desired mechanical performance in various engineering applications.展开更多
The study investigated the influence of Ce alloying and cold rolling on the activation behavior of V_(70)Ti_(10)Cr_(20)-based alloys.The activation conditions of single cold rolled(V_(70)Ti_(10)Cr_(20)-0.3)and single ...The study investigated the influence of Ce alloying and cold rolling on the activation behavior of V_(70)Ti_(10)Cr_(20)-based alloys.The activation conditions of single cold rolled(V_(70)Ti_(10)Cr_(20)-0.3)and single Ce replaced(V_(70)Ti_(10)Cr_(20)Ce_(1))samples were reduced from the origin-al two heat treatments to one heat treatment,and the incubation time was about 105 min.Unexpectedly,the two modification methods produce excellent synergistic effects that the co-modified sample(V_(70)Ti_(10)Cr_(20)Ce_(1)-0.5)was activated at room temperature(25℃)without incubation period,and reached saturation capacity(4wt%)within 12 min.Further studies show that CeO_(2) formed through Ce doping,serves as an active site for hydrogen absorption,facilitating the passage of hydrogen atoms through the dense oxide layer on the surface of vanadium-based alloys.Upon the foundation of Ce doping,cold rolling leads to the aggregation of dislocations around CeO_(2) sites,thereby further establishing a hydrogen diffusion pathway from the surface into the bulk phase,thus significantly improving the activation performance of the alloy.This work establishes a robust basis for the practical engineering use of vanadium-based hydrogen storage alloys.展开更多
GENERALLY the following two processes will take place simultaneously during hot deformation: one is work hardening caused by the increase of dislocation density on account of slip deforma-tion; the other is softening ...GENERALLY the following two processes will take place simultaneously during hot deformation: one is work hardening caused by the increase of dislocation density on account of slip deforma-tion; the other is softening caused by the process of recovery and recrystallization. The overalleffect of the development of the two contrary processes is influenced by deformation tempera-ture, rate and quantities. Among them temperature controls the rate of self-diffusion, whichaffects the proceeding of recovery and recrystallization as well. During recovery the dislocationdensity is mainly determined by deformation rate (ε) and strain quantities (ε).展开更多
Crystal orientation governs the plasticity of intermetallic alloys,yet the atomicscale mechanisms linking defect dynamics to mechanical properties remain elusive.Here,we unveil unprecedented deformation pathways in si...Crystal orientation governs the plasticity of intermetallic alloys,yet the atomicscale mechanisms linking defect dynamics to mechanical properties remain elusive.Here,we unveil unprecedented deformation pathways in single-crystal γ-TiAl through largescale molecular dynamics simulations under uniaxial tension across four crystallographic orientations:[100],[112],[110],and[111].Strikingly,a metastable body-centered cubic(BCC)phase emerges transiently during[100]-oriented stretching,acting as a critical bridge between elastic and plastic regimes—a phenomenon unreported in γ-TiAl.For[110]and[111]orientations,we identify a hierarchical defect evolution cascade(intrinsic stacking faults→extrinsic stacking faults→twin boundary(ISF→ESF→TB))driven by intersecting stacking faults and Shockley partial dislocation interactions,which govern twin boundary nucleation and growth.In contrast,[112]-oriented deformation adheres to conventional dislocation-mediated plasticity.These findings reveal how crystallographic anisotropy dictates defect dynamics,offering atomic-scale insights into deformation twinning and transient phase transitions.This work bridges atomistic processes to macroscopic properties,advancing the design of next-generation lightweight hightemperature materials.展开更多
基金The project supported by National Natural Science Foundation of China(Grant No.19974027)the Foundation of Sichuan Provincial Education Committee(Grant No.01LB04)
文摘The formation mechanism for the body-centered cubic structure of cluster is proposed and its total energy curve is calculated by the method of a Modified Arrangement Channel Quantum Mechanics. The energy is the function of separation R between the nuclei at the center and an apex of the body-centered cubic structure. The result of the calculation shows that the curve has a minimal energy . The binding energy of with respect to was calculated to be 0.8857 a.u. This means that the cluster ofmay be formed in the body-centered cubic structure of .
文摘Body-centered tetragonal C4 （bct C4） is a new form of crystalline spa carbon, which is found to be transparent, dynamically stable at zero pressure and more stable than graphite beyond 18.6 GPa. Symmetry analysis of the vibrational modes of bct C4 at Brillouin zone center is performed, Raman and infrared active modes are identified. The analysis results show that, different from cubic diamond and hexagonal diamond, there is an infrared active mode in bct C4. Based on first-principle method within the local density approximation, vibrational frequencies, Born effective charge tensors, and infrared absorption intensity of bct C4 are obtained. The vibrational modes of bct C4 are presented and compared with those of cubic diamond and hexagonal diamond in detail
文摘Background: The roots of autism spectrum disorders become evident in first attunement mechanisms between mother and child that allow a first level of mentalizing. Neurosciences and current developmental theories confirm the existence of defensive mechanisms related to body and affectivity that psychodynamic theories had already highlighted. Reading child’s behavior not only by administering tests but also through careful clinical observations allows a better understanding of the communication and social difficulties present in autistic children. The identification of the zone of proximal development can promote a therapeutic intervention that respects the individuality of the child and the specificity of his relational approach to the world. Conclusion: The paper presents the theoretical principles of a body-centered therapy to promote the attunement processes necessary to activate cognitive resources.
基金the foundation of Westlake University for financial supportThe work at Zhejiang University was supported by the National Key Research and Development Program of China(2017YFA0303002)。
文摘The introduction of carbon interstitials into high-entropy alloys(HEAs)provides an effective way to improve their properties.However,all such HEA systems explored so far are limited to those with the face-centered-cubic(fcc)structure.Here we report the structural,mechanical and physical properties of the refractory(Nb_(0.375)Ta_(0.25)Mo_(0.125)W_(0.125)Re_(0.125))_(100−x)C_(x) HEAs over a wide x range of 0≤x≤20.It is found that,whereas the starting HEA(x=0)is composed of a major body-centered-cubic(bcc)phase with significant impurities,the bcc phase fraction increases with the C concentration and achieves almost 100%at x=20.Moreover,the increase of C content x results in an expansion of the bcc lattice,an enhancement of the microhardness,an increase in residual resistivity and a small variation of density of states at the Fermi level.All these features are consistent with the expectation that carbon atoms occupy the interstitial site.For x≥11.1,the X-ray photoelectron spectroscopy indicates the bond formation between the carbon and metal atoms,suggesting that some carbon atoms may also reside in the lattice site.In addition,a semiquantitative analysis shows that the enhanced mixing entropy caused by carbon addition plays a key role in stabilizing the(nearly)single solid-solution phase.Our study not only provides the first series of carbon interstitial HEAs with a bcc structure,but also helps to better understand the alloying behavior of carbon in refractory HEAs.
基金supported by the Key Project of the National Natural Science Foundation of China(11234011)
文摘Submicron and nanostructured body-centered cubic(BCC) metals exhibit unusual mechanical performance compared to their bulk coarse-grained counterparts, including high yield strength and outstanding ductility. These properties are important for their applications in micro-, nano-and even atomic-scale devices as well as for their usages as components for enhancing the performances of structural materials. One aspect of the unusual mechanical properties of small-sized BCC metals is closely related to their dimensional confinement. Decreasing the dimensions of single crystalline metals or the grain sizes of polycrystalline metals contributes significantly to the strengthening of the small-sized BCC metals.In the last decade, significant progress has been achieved in understanding the plasticity and deformation behaviors of small-sized BCC metals. This paper aims to provide a comprehensive review on the current understanding of size effects on the plasticity and deformation mechanisms of small-sized BCC metals. The techniques used for in situ characterization of the deformation behavior and mechanical properties of small-sized samples are also presented.
基金supported by the National Key Research and Development Program of China(Grant Nos.2019YFA0209900 and 2017YFB0304403)the National Natural Science Foundation of China(Grant No.12075179)+1 种基金the Nuclear Material Technology Innovation Center Project(Grant No.ICNM 2020 ZH05)the Continuous Basic Scientific Research Project(Grant No.WDJC-2019-10)
文摘High-entropy alloys greatly expand the alloy design range and offer new possibilities for improving material performance.Based on the worldwide research efforts in the last decade,the excellent mechanical properties and promising radiation and corrosion resistance of this group of materials have been demonstrated.High-entropy alloys with body-centered cubic(BCC)structures,especially refractory high-entropy alloys,are considered as promising materials for high-temperature applications in advanced nuclear reactors.However,the extreme reactor conditions including high temperature,high radiation damage,high stress,and complex corrosive environment require a comprehensive evaluation of the material properties for their actual service in nuclear reactors.This review summarizes the current progress on BCC high-entropy alloys from the aspects of neutron economy and activation,mechanical properties,high-temperature stability,radiation resistance,as well as corrosion resistance.Although the current development of BCC high-entropy alloys for nuclear applications is still at an early stage as the large design space of this group of alloys has not been fully explored,the current research findings provide a good basis for the understanding and prediction of material behaviors with different compositions and microstructures.Further in-depth understanding of the degradation mechanisms and characterization of material properties in response to conditions close to reactor environment are necessary.A critical down-selection of potential candidates is also crucial for further comprehensive evaluation and engineering validation.
基金supported by the National Natural Science Foundation of China(Grant Nos.51931005 and 51901235).
文摘Martensite is one of the most important structures determining the ability to tailor the performance of steel and several other engineering materials.In previous studies,the face-centered cubic(FCC)to hexag-onal close-packed(HCP)(or body-centered cubic(BCC))martensitic transformation and the FCC to body-centered tetragonal(BCT)(or BCC)martensitic transformation during deformation and quenching were widely investigated;these transformations usually improve the plasticity and strength of steel,respec-tively.In this work,detailed transmission electron microscopy(TEM)observations and electron diffraction pattern analyses of the BCT and BCC twins are performed along the[110],[131],and[¯153]zone axes.The transformation of BCT twins into BCC twins along the[131]zone axis is also analyzed through in situ heating during the TEM observations.The high-resolution TEM observations of mutually perpendicular BCT variants are consistent with the atomic arrangement obtained for the quenching pathway during the martensitic transformation.In addition,different orientation relationships between austenite and marten-site are explained in terms of the atomic migration occurring during the deformation pathway and the quenching pathway of the martensitic transformation.
基金Projects(51471087,61370042,21173041,11204031,11472080)supported by the National Natural Science Foundation of ChinaProject(13KJA430003)supported by the Jiangsu Higher Education Institutions of ChinaProject(BK20141336)supported by the Natural Science Foundation of Jiangsu Province,China
文摘In order to improve the discharge capacity and cyclic life of Mg-Co-based alloy, ternary Mg45M5Co50 （M=Pd, Zr） alloys were synthesized via mechanical alloying. TEM analysis demonstrates that these alloys all possess body-centered cubic （BCC） phase in nano-crystalline. Electrochemical experiments show that Mg45Zr5Co50 electrode exhibits the highest capacity （425 mA·h/g） among the Mg45M5Co50 （M=Mg, Pd, Zr） alloys. And Mg45Pd5Co50 electrode lifts not only the initial discharge capacity （379 mA·h/g）, but also the discharge kinetics, e.g., exchange current density and hydrogen diffusion ability from that of Mg50Co50. It could be concluded that the electrochemical performances were enhanced by substituting Zr and Pd for Mg in Mg-Co-based alloy.
基金supported by an Australian Research Council Discovery Project(Grant No.DP160104632)an Aus-tralian Government Research Training Program Scholarship.Y.J.Chen acknowledges the support provided by the Australian Re-search Council(Grant No.DE210101773).
文摘Fe_(72.4)Co_(13.9)Cr_(10.4)Mn_(2.7)B_(0.34)high entropy steel was prepared by magnetron sputtering.The alloy exhibits a high yield strength of 2.92±0.36 GPa while achieving appreciable plasticity of 13.7±1.9%at the ultimate compressive strength(3.37±0.36 GPa).The distribution of iron and chromium shows an un-usual,characteristic spinodal-like pattern at the nanometer scale,where compositions of Fe and Cr show strong anticorrelation and vary by as much as 20 at.%.The high strength is largely attributable to the compositional modulations,combined with fine grains with body-centered cubic(BCC)crystal structure,as well as grain boundary segregation of interstitial boron.The impressive plasticity is accommodated by the formation and operation of multiplanar,multicharacter dislocation slips,mediated by coherent in-terfaces,and controlled by shear bandings.The excellent strength-ductility combination is thus enabled by a range of distinctive strengthening mechanisms,rendering the new alloy a potential candidate for safety-critical,load-bearing structural applications.
基金supported by National Key R&D Program of China(Grant No.2023YFB3712002)E.M.acknowledge National Natural Science Foundation of China(Grant No.52231001).
文摘Refractory multi-principal element alloys(RMPEAs)have garnered attention for their potential in high-temperature applications.Additive manufacturing(AM)provides opportunities to tailor RMPEAs’microstructures to enhance these properties.However,controlling defects and addressing the challenges posed by the complex thermal history during the AM process are crucial for optimizing RMPEAs’performance.This study aims to fabricate a high-quality oxygen-doped NbTiZr alloys using laser powder bed fusion and investigate their microstructure and mechanical properties.Our analysis reveals refined grain sizes and a periodic combination of fine near-equiaxed and columnar grain morphologies in the AM-fabricated alloy.Its substructure is characterized by the coexistence of loosely defined cellular dislocation networks and elemental segregation.Compared to its cast counterpart,the additively manufactured alloy exhibits a combination of high yield strength,excellent tensile ductility,and enhanced work hardening.These attributes make the AM-fabricated oxygen-doped NbTiZr alloy a promising candidate for applications required balanced mechanical properties.Understanding the specific effects of different crystal structures and deformation mechanisms is essential for optimizing AM processes to tailor the microstructure and achieve the desired mechanical performance in various engineering applications.
基金supported by the Natural Science Foundation of Zhejiang Province(No.LQ24E010003)the Baima Lake Laboratory Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(Nos.LBMHY24E060004 and LBMHY24E060005)+1 种基金the Guangxi Major Science and Technology Program(No.AA24206007)Science and Technology Plan Project of Zhejiang Province(No.2025C01171).
文摘The study investigated the influence of Ce alloying and cold rolling on the activation behavior of V_(70)Ti_(10)Cr_(20)-based alloys.The activation conditions of single cold rolled(V_(70)Ti_(10)Cr_(20)-0.3)and single Ce replaced(V_(70)Ti_(10)Cr_(20)Ce_(1))samples were reduced from the origin-al two heat treatments to one heat treatment,and the incubation time was about 105 min.Unexpectedly,the two modification methods produce excellent synergistic effects that the co-modified sample(V_(70)Ti_(10)Cr_(20)Ce_(1)-0.5)was activated at room temperature(25℃)without incubation period,and reached saturation capacity(4wt%)within 12 min.Further studies show that CeO_(2) formed through Ce doping,serves as an active site for hydrogen absorption,facilitating the passage of hydrogen atoms through the dense oxide layer on the surface of vanadium-based alloys.Upon the foundation of Ce doping,cold rolling leads to the aggregation of dislocations around CeO_(2) sites,thereby further establishing a hydrogen diffusion pathway from the surface into the bulk phase,thus significantly improving the activation performance of the alloy.This work establishes a robust basis for the practical engineering use of vanadium-based hydrogen storage alloys.
文摘GENERALLY the following two processes will take place simultaneously during hot deformation: one is work hardening caused by the increase of dislocation density on account of slip deforma-tion; the other is softening caused by the process of recovery and recrystallization. The overalleffect of the development of the two contrary processes is influenced by deformation tempera-ture, rate and quantities. Among them temperature controls the rate of self-diffusion, whichaffects the proceeding of recovery and recrystallization as well. During recovery the dislocationdensity is mainly determined by deformation rate (ε) and strain quantities (ε).
基金financial support by the National Science and Technology Major Project(No.2025ZD0618600)the General Projects for Key Industrial Chain Technology Research and Development of Xi'an(No.24ZDCYJSGG0050)the Key Technology Project of Ningbo"Science and Technology Innovation Yongjiang 2035"(No.2024Z155).
文摘Crystal orientation governs the plasticity of intermetallic alloys,yet the atomicscale mechanisms linking defect dynamics to mechanical properties remain elusive.Here,we unveil unprecedented deformation pathways in single-crystal γ-TiAl through largescale molecular dynamics simulations under uniaxial tension across four crystallographic orientations:[100],[112],[110],and[111].Strikingly,a metastable body-centered cubic(BCC)phase emerges transiently during[100]-oriented stretching,acting as a critical bridge between elastic and plastic regimes—a phenomenon unreported in γ-TiAl.For[110]and[111]orientations,we identify a hierarchical defect evolution cascade(intrinsic stacking faults→extrinsic stacking faults→twin boundary(ISF→ESF→TB))driven by intersecting stacking faults and Shockley partial dislocation interactions,which govern twin boundary nucleation and growth.In contrast,[112]-oriented deformation adheres to conventional dislocation-mediated plasticity.These findings reveal how crystallographic anisotropy dictates defect dynamics,offering atomic-scale insights into deformation twinning and transient phase transitions.This work bridges atomistic processes to macroscopic properties,advancing the design of next-generation lightweight hightemperature materials.
