Organic ferroelastics with metal free features and intrinsically light weight are highly desirable for future applications in flexible,smart and biocompatible devices.However,organoferroelastics with plastic phase tra...Organic ferroelastics with metal free features and intrinsically light weight are highly desirable for future applications in flexible,smart and biocompatible devices.However,organoferroelastics with plastic phase transition have rarely been reported yet.Herein,we discovered ferroelasticity in a pair of organic enantiomers,(1S and/or 1R)-2,10-camphorsultam(S-and R-CPS),which undergoes a high-T_(c)plastic phase transition.Both large entropies change of∼45 J mol^(-1)K^(-1)and evidently ductile deformation process confirm the plastic phase feature.Strip-like ferroelastic domain patterns and bidirectional domain movements have been observed via polarized light microscopy and nanoindentation technique,respectively.This work highlights the discovery of organic ferroelastic combining the features of enantiomers and plastic phase transition,which contributes insights into exploration of organic multifunctional materials.展开更多
1 Scope This standard specifies the definition, classification, technical requirements, test methods, inspection rules, packing, marking, transportation and quality certificate of corundum block containing plastic ph...1 Scope This standard specifies the definition, classification, technical requirements, test methods, inspection rules, packing, marking, transportation and quality certificate of corundum block containing plastic phase.展开更多
For the first time, for different organic and inorganic compounds possessing the plastic crystalline phase, a new semiempirical equation describing dependence of their fusion enthalpies on such physico-chemical quanti...For the first time, for different organic and inorganic compounds possessing the plastic crystalline phase, a new semiempirical equation describing dependence of their fusion enthalpies on such physico-chemical quantities as normal melting temperature, surface tension, molar volume and critical molar volume is received on the base of the principle of corresponding states and the energy equipartition theorem. Moreover, the proposed equation allows one to take into account the particularities of one-particle molecular rotation in the plastic crystalline phase.展开更多
The relations of bulk modulus, shear modulus, Young's modulus and the Poisson's ratio with porosity of foam plastics are determined by a three phase spheroidal model commonly used in Composite Mechanics. The r...The relations of bulk modulus, shear modulus, Young's modulus and the Poisson's ratio with porosity of foam plastics are determined by a three phase spheroidal model commonly used in Composite Mechanics. The results are compared with those using differential scheme. It is shown that the material properties derived from the present model normally are larger than those obtained by differential scheme for foam plastics with identical porosity. The differences in shear moduli and Young's moduli obtained by the two methods are small but they are larger for bulk moduli of incompressible matrix and Poisson's ratios. The Young's moduli of high density foam plastics derived by the present model agree better with experimental ones.展开更多
High temperature rupture specimens with different rapture plasticity are investigated. The rupture fracture failure of Inconel 783 superalloy is researched by analyzing the fracture surface and microstructure of the r...High temperature rupture specimens with different rapture plasticity are investigated. The rupture fracture failure of Inconel 783 superalloy is researched by analyzing the fracture surface and microstructure of the rupture specimens. The intergranular β phase precipitated sufficiently with favorable morphology can efficiently strengthen grain boundaries that can achieve a full plastic deformation of grains. Additionally, the intergranular β phase can effectively restrain the occurrence and expansion of intergranular cracks during the rupture test. The intergranular β phase insufficiently precipitated can weaken the intergranular cohesion and lead to the occurrence and expansion of cracks; thus, the grains cannot be fully deformed before breaking. Therefore, the β phase precipitated in the grain boundaries can significantly increase the rupture plasticity of Inconel 783 superalloy.展开更多
Phase transformations in steels play a major role on the generation of residual stresses and distortions during thermal processes such as welding and heat treatments. In this paper, we focus on the influence of phase ...Phase transformations in steels play a major role on the generation of residual stresses and distortions during thermal processes such as welding and heat treatments. In this paper, we focus on the influence of phase transformations on the plastic behaviour of a low-alloy steel. It is now well known that the plastic strain rate can then be decomposed as the sum of two terms. The first one corresponds to classical plasticity while the second one is due to the evolution of the transformation and is usually referred to as corresponding to transformation induced plasticity. A theoretical approach of the problem has been achieved ([1][2][3]] and a macroscopic model has been proposed in the case of ideal-plastic phases. The theoretical approach has been assessed and completed using micromechanical numerical simulations but these were based on rather coarse 3D meshes due to limited computer capabilities in the 80’s. This paper presents new finite element micromechanical calculations using refined meshes to analyse the classical plastic behaviour and transformation induced plasticity. The results of the computations are discussed and compared with the calculations initially performed. Finally improvements of the macroscopic model are proposed.展开更多
Additive manufacturing technology based on laser powder bed fusion(LPBF)offers a novel approach for fabricating bulk metallic glass(BMG)products without restriction in size and geometry.Nevertheless,the BMGs prepared ...Additive manufacturing technology based on laser powder bed fusion(LPBF)offers a novel approach for fabricating bulk metallic glass(BMG)products without restriction in size and geometry.Nevertheless,the BMGs prepared by LPBF usually suffered from less plasticity and poorer fracture toughness as compared to their cast counterparts due to partial crystallization in heat-affected zones(HAZs).Since crystallization in HAZs is hard to avoid completely in LPBF BMGs,it is desirable to design a suitable alloy system,in which only ductile crystalline phase,instead of brittle intermetallics,is formed in HAZs.This unique structure could effectively increase the toughness/plasticity of the LPBF BMGs.To achieve this goal,a quaternary BMG system with a composition of Zr_(47.5)Cu_(45.5)Al_(5)Co_(2)is adopted and subjected to LPBF.It is found that nearly a single phase of B_(2)-ZrCu is precipitated in HAZs,while a fully amorphous phase is formed in molten pools(MPs).This B_(2)phase reinforced BMG composite exhibits excellent mechanical properties with enhanced plasticity and toughness.Furthermore,it is easy to modulate the mechanical properties by altering the amount of the B_(2)phase via adjusting the laser energy input.Finally,the best combination of strength,plasticity,and notch toughness is obtained in the BMG composite containing 27.4%B_(2)phase and 72.6%amorphous phase,which exhibits yield strength(σ_(s))of 1423 MPa,plastic strain(ε_(p))of 4.65%,and notch toughness(K_(q))of 53.9 MPa m 1/2.Furthermore,a notable strain-hardening is also observed.The improvement of plasticity/toughness and appearance of strain-hardening behavior are mainly due to the martensite phase transformation from the B_(2)phase to the Cm phase during plastic deformation(i.e.,the phase transformation-induced plasticity effect).The current work provides a guide for making advanced BMGs and BMG composites by additive manufacturing.展开更多
Coupled relations among temperature, phase transformation and stress have beendiscussed here in the present paper. Thermo-elasto-plastic constitutive equationsincluding creep and iterative finite element formulation d...Coupled relations among temperature, phase transformation and stress have beendiscussed here in the present paper. Thermo-elasto-plastic constitutive equationsincluding creep and iterative finite element formulation during continuous casting withphase change have also been presented.展开更多
Based on the assumption that a representative element of apearlitic steel is an aggregate of numerous spherical pearliticcolonies with randomly distributed orientations, and that each colonyis com- posed of many paral...Based on the assumption that a representative element of apearlitic steel is an aggregate of numerous spherical pearliticcolonies with randomly distributed orientations, and that each colonyis com- posed of many parallel fine lamellas of ferrite andcementite, a description for the dual-phase pearlitic steel isobtained by making use of a microstructure-based constitutiveequation for a single dual-phase pearlitic colony and the Hill'sself-consistent scheme. The elastoplastic response of dual-phasepearlitic steel BS11 subjected to asymmetrically cyclic loading isanalyzed, and a comparison with the experimental results showssatisfacto- ry agreement. The non-proportional cyclic plasticity ofBS11 is also analyzed, in which stress develops along a semi-circlein a biaxial tension/compression and shear stress plane, as istypically experienced by the sur- face elements in rolling andsliding contact.展开更多
Phase transitions widely exist in nature and occur when some control parameters are changed. In neural systems, their macroscopic states are represented by the activity states of neuron populations, and phase transiti...Phase transitions widely exist in nature and occur when some control parameters are changed. In neural systems, their macroscopic states are represented by the activity states of neuron populations, and phase transitions between different activity states are closely related to corresponding functions in the brain. In particular, phase transitions to some rhythmic synchronous firing states play significant roles on diverse brain functions and disfunctions, such as encoding rhythmical external stimuli, epileptic seizure, etc. However, in previous studies, phase transitions in neuronal networks are almost driven by network parameters （e.g., external stimuli）, and there has been no investigation about the transitions between typical activity states of neuronal networks in a self-organized way by applying plastic connection weights. In this paper, we discuss phase transitions in electrically coupled and lattice-based small-world neuronal networks （LBSW networks） under spike-timing-dependent plasticity （STDP）. By applying STDP on all electrical synapses, various known and novel phase transitions could emerge in LBSW networks, particularly, the phenomenon of self-organized phase transitions （SOPTs）： repeated transitions between synchronous and asynchronous firing states. We further explore the mechanics generating SOPTs on the basis of synaptic weight dynamics.展开更多
基金supported by the National Natural Science Foundation of China(No.22271131)the Department of Science and Technology in Jiangxi Province(No.20225BCJ23029).
文摘Organic ferroelastics with metal free features and intrinsically light weight are highly desirable for future applications in flexible,smart and biocompatible devices.However,organoferroelastics with plastic phase transition have rarely been reported yet.Herein,we discovered ferroelasticity in a pair of organic enantiomers,(1S and/or 1R)-2,10-camphorsultam(S-and R-CPS),which undergoes a high-T_(c)plastic phase transition.Both large entropies change of∼45 J mol^(-1)K^(-1)and evidently ductile deformation process confirm the plastic phase feature.Strip-like ferroelastic domain patterns and bidirectional domain movements have been observed via polarized light microscopy and nanoindentation technique,respectively.This work highlights the discovery of organic ferroelastic combining the features of enantiomers and plastic phase transition,which contributes insights into exploration of organic multifunctional materials.
文摘1 Scope This standard specifies the definition, classification, technical requirements, test methods, inspection rules, packing, marking, transportation and quality certificate of corundum block containing plastic phase.
文摘For the first time, for different organic and inorganic compounds possessing the plastic crystalline phase, a new semiempirical equation describing dependence of their fusion enthalpies on such physico-chemical quantities as normal melting temperature, surface tension, molar volume and critical molar volume is received on the base of the principle of corresponding states and the energy equipartition theorem. Moreover, the proposed equation allows one to take into account the particularities of one-particle molecular rotation in the plastic crystalline phase.
基金Supported by the National Natural Science Foundation of China and Laboratory for Nonlinear Mechanics of Continuous Media,Institute of Mechanics,Chinese Academy of Sciences.
文摘The relations of bulk modulus, shear modulus, Young's modulus and the Poisson's ratio with porosity of foam plastics are determined by a three phase spheroidal model commonly used in Composite Mechanics. The results are compared with those using differential scheme. It is shown that the material properties derived from the present model normally are larger than those obtained by differential scheme for foam plastics with identical porosity. The differences in shear moduli and Young's moduli obtained by the two methods are small but they are larger for bulk moduli of incompressible matrix and Poisson's ratios. The Young's moduli of high density foam plastics derived by the present model agree better with experimental ones.
文摘High temperature rupture specimens with different rapture plasticity are investigated. The rupture fracture failure of Inconel 783 superalloy is researched by analyzing the fracture surface and microstructure of the rupture specimens. The intergranular β phase precipitated sufficiently with favorable morphology can efficiently strengthen grain boundaries that can achieve a full plastic deformation of grains. Additionally, the intergranular β phase can effectively restrain the occurrence and expansion of intergranular cracks during the rupture test. The intergranular β phase insufficiently precipitated can weaken the intergranular cohesion and lead to the occurrence and expansion of cracks; thus, the grains cannot be fully deformed before breaking. Therefore, the β phase precipitated in the grain boundaries can significantly increase the rupture plasticity of Inconel 783 superalloy.
文摘Phase transformations in steels play a major role on the generation of residual stresses and distortions during thermal processes such as welding and heat treatments. In this paper, we focus on the influence of phase transformations on the plastic behaviour of a low-alloy steel. It is now well known that the plastic strain rate can then be decomposed as the sum of two terms. The first one corresponds to classical plasticity while the second one is due to the evolution of the transformation and is usually referred to as corresponding to transformation induced plasticity. A theoretical approach of the problem has been achieved ([1][2][3]] and a macroscopic model has been proposed in the case of ideal-plastic phases. The theoretical approach has been assessed and completed using micromechanical numerical simulations but these were based on rather coarse 3D meshes due to limited computer capabilities in the 80’s. This paper presents new finite element micromechanical calculations using refined meshes to analyse the classical plastic behaviour and transformation induced plasticity. The results of the computations are discussed and compared with the calculations initially performed. Finally improvements of the macroscopic model are proposed.
基金supported by the National Natural Science Foundation of China(Grant Nos.52192604 and 52201181)the Key R&D Program of Hubei(No.2022BAA023).
文摘Additive manufacturing technology based on laser powder bed fusion(LPBF)offers a novel approach for fabricating bulk metallic glass(BMG)products without restriction in size and geometry.Nevertheless,the BMGs prepared by LPBF usually suffered from less plasticity and poorer fracture toughness as compared to their cast counterparts due to partial crystallization in heat-affected zones(HAZs).Since crystallization in HAZs is hard to avoid completely in LPBF BMGs,it is desirable to design a suitable alloy system,in which only ductile crystalline phase,instead of brittle intermetallics,is formed in HAZs.This unique structure could effectively increase the toughness/plasticity of the LPBF BMGs.To achieve this goal,a quaternary BMG system with a composition of Zr_(47.5)Cu_(45.5)Al_(5)Co_(2)is adopted and subjected to LPBF.It is found that nearly a single phase of B_(2)-ZrCu is precipitated in HAZs,while a fully amorphous phase is formed in molten pools(MPs).This B_(2)phase reinforced BMG composite exhibits excellent mechanical properties with enhanced plasticity and toughness.Furthermore,it is easy to modulate the mechanical properties by altering the amount of the B_(2)phase via adjusting the laser energy input.Finally,the best combination of strength,plasticity,and notch toughness is obtained in the BMG composite containing 27.4%B_(2)phase and 72.6%amorphous phase,which exhibits yield strength(σ_(s))of 1423 MPa,plastic strain(ε_(p))of 4.65%,and notch toughness(K_(q))of 53.9 MPa m 1/2.Furthermore,a notable strain-hardening is also observed.The improvement of plasticity/toughness and appearance of strain-hardening behavior are mainly due to the martensite phase transformation from the B_(2)phase to the Cm phase during plastic deformation(i.e.,the phase transformation-induced plasticity effect).The current work provides a guide for making advanced BMGs and BMG composites by additive manufacturing.
文摘Coupled relations among temperature, phase transformation and stress have beendiscussed here in the present paper. Thermo-elasto-plastic constitutive equationsincluding creep and iterative finite element formulation during continuous casting withphase change have also been presented.
基金the National Natural Science Foundation of China (No.19872079)the Fund of the Ministry of Education of China.
文摘Based on the assumption that a representative element of apearlitic steel is an aggregate of numerous spherical pearliticcolonies with randomly distributed orientations, and that each colonyis com- posed of many parallel fine lamellas of ferrite andcementite, a description for the dual-phase pearlitic steel isobtained by making use of a microstructure-based constitutiveequation for a single dual-phase pearlitic colony and the Hill'sself-consistent scheme. The elastoplastic response of dual-phasepearlitic steel BS11 subjected to asymmetrically cyclic loading isanalyzed, and a comparison with the experimental results showssatisfacto- ry agreement. The non-proportional cyclic plasticity ofBS11 is also analyzed, in which stress develops along a semi-circlein a biaxial tension/compression and shear stress plane, as istypically experienced by the sur- face elements in rolling andsliding contact.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11135001 and 11174034)
文摘Phase transitions widely exist in nature and occur when some control parameters are changed. In neural systems, their macroscopic states are represented by the activity states of neuron populations, and phase transitions between different activity states are closely related to corresponding functions in the brain. In particular, phase transitions to some rhythmic synchronous firing states play significant roles on diverse brain functions and disfunctions, such as encoding rhythmical external stimuli, epileptic seizure, etc. However, in previous studies, phase transitions in neuronal networks are almost driven by network parameters （e.g., external stimuli）, and there has been no investigation about the transitions between typical activity states of neuronal networks in a self-organized way by applying plastic connection weights. In this paper, we discuss phase transitions in electrically coupled and lattice-based small-world neuronal networks （LBSW networks） under spike-timing-dependent plasticity （STDP）. By applying STDP on all electrical synapses, various known and novel phase transitions could emerge in LBSW networks, particularly, the phenomenon of self-organized phase transitions （SOPTs）： repeated transitions between synchronous and asynchronous firing states. We further explore the mechanics generating SOPTs on the basis of synaptic weight dynamics.
