As a new structure of solid matter quasicrystal brings profound new ideas to the traditional condensed matter physics, its elastic equations are more complicated than that of traditional crystal. A contact problem of ...As a new structure of solid matter quasicrystal brings profound new ideas to the traditional condensed matter physics, its elastic equations are more complicated than that of traditional crystal. A contact problem of decagonal two? dimensional quasicrystal material under the action of a rigid flat die is solved satisfactorily by introducing displacement function and using Fourier analysis and dual integral equations theory, and the analytical expressions of stress and displacement fields of the contact problem are achieved. The results show that if the contact displacement is a constant in the contact zone, the vertical contact stress has order -1/2 singularity on the edge of contact zone, which provides the important mechanics parameter for contact deformation of the quasicrystal.展开更多
Double-well potentials are used for molecular dynamics simulation in monatomic systems. The potentials change as their parameters are adjusted, resulting in different structures. Of particular interest, we obtain deca...Double-well potentials are used for molecular dynamics simulation in monatomic systems. The potentials change as their parameters are adjusted, resulting in different structures. Of particular interest, we obtain decagonal and dodecagonal quasicrystals by simulations. We also verify the results and explain the formation of quasicrystals from the perspective of potential energy.展开更多
In this work, an elegant method is proposed to derive the thermoelastic field in- duced by thermomechanical loadings in a decagonal quasicrystalline composite composed of an infinite matrix reinforced by an elliptical...In this work, an elegant method is proposed to derive the thermoelastic field in- duced by thermomechanical loadings in a decagonal quasicrystalline composite composed of an infinite matrix reinforced by an elliptical inclusion. The thermomechanical loadings include a uniform temperature change, remote uniform in-plane heat fluxes and remote uniform in-plane stresses. The corresponding boundary value problem is ultimately reduced to the solution of two independent sets of four coupled linear algebraic equations, each of which involves four complex constants characterizing the internal stress field. The solution demonstrates that a uniform tem- perature change and remote uniform stresses will induce an internal uniform stress field, and that uniform heat fluxes will result in a linearly distributed internal stress field within the elliptical inclusion. The induced uniform rigid body rotation within the inclusion is given explicitly.展开更多
This investigation presents the Green functions for a decagonal quasicrystalline ma- terial with a parabolic boundary subject to a line force and a line dislocation by means of the complex variable method. The surface...This investigation presents the Green functions for a decagonal quasicrystalline ma- terial with a parabolic boundary subject to a line force and a line dislocation by means of the complex variable method. The surface Green functions are treated as a special case, and the explicit expressions of displacements and hoop stress at the parabolic boundary are also given. Finally, the stresses and displacements induced by a phonon line force acting at the origin of the lower half-space are presented.展开更多
We investigate the elastic field near the tip of an anticrack in a homogeneous decagonal quasicrystalline material subject to plane strain deformations. The phonon and phason stresses exhibit a square root singularity...We investigate the elastic field near the tip of an anticrack in a homogeneous decagonal quasicrystalline material subject to plane strain deformations. The phonon and phason stresses exhibit a square root singularity at the anticrack tip. Two realvalued phonon stress intensity factors and two real-valued phason stress intensity factors are introduced to scale four separate modes of deformation. We obtain four analytic functions which completely characterize the induced phonon and phason stresses as well as the displacement field. In particular, we derive a concise yet elegant representation of the anticrack contraction force.展开更多
It is undeniable that wireless communication technology has become a very important component of modern society. One aspect of modern society in which application of wireless communication technologies has tremendous ...It is undeniable that wireless communication technology has become a very important component of modern society. One aspect of modern society in which application of wireless communication technologies has tremendous potential is in agricultural production. This is especially true in the area of sensing and transmission of relevant farming information such as weather, crop development, water quantity and quality, among others, which would allow farmers to make more accurate and timely farming decisions. A good example would be the application of wireless communication technology to transmit soil moisture data in real time to help farmers make irrigation scheduling decisions. Although many systems are commercially available for soil moisture monitoring, there are still many important factors, such as cost, limiting widespread adoption of this technology among growers. Our objective in this study was, therefore, to develop and test an affordable wireless communication system for monitoring soil moisture using Decagon EC-5 sensors. The new system uses Arduino-compatible microcontrollers and communication systems to sample and transmit values from four Decagon EC-5 soil moisture sensors. Developing the system required conducting lab calibrations for the EC-5 sensors for the microcontroller operating in either 10-bit or 12-bit analog-to-digital converter (ADC) resolution. The system was successfully tested in the field and reliably collected and transmitted data from a wheat field for more than two months.展开更多
The interface crack problems in the two-dimensional(2D)decagonal quasicrystal(QC)coating are theoretically and numerically investigated with a displacement discontinuity method.The 2D general solution is obtained base...The interface crack problems in the two-dimensional(2D)decagonal quasicrystal(QC)coating are theoretically and numerically investigated with a displacement discontinuity method.The 2D general solution is obtained based on the potential theory.An analogy method is proposed based on the relationship between the general solutions for 2D decagonal and one-dimensional(1D)hexagonal QCs.According to the analogy method,the fundamental solutions of concentrated point phonon displacement discontinuities are obtained on the interface.By using the superposition principle,the hypersingular boundary integral-differential equations in terms of displacement discontinuities are determined for a line interface crack.Further,Green’s functions are found for uniform displacement discontinuities on a line element.The oscillatory singularity near a crack tip is eliminated by adopting the Gaussian distribution to approximate the delta function.The stress intensity factors(SIFs)with ordinary singularity and the energy release rate(ERR)are derived.Finally,a boundary element method is put forward to investigate the effects of different factors on the fracture.展开更多
A decagonal quasicrystal, which is weakened by an arc-shaped crackpenetrating through the solid in the period direction, and which is subjected to remote uniformphonon stresses, is investigated by applying the complex...A decagonal quasicrystal, which is weakened by an arc-shaped crackpenetrating through the solid in the period direction, and which is subjected to remote uniformphonon stresses, is investigated by applying the complex variable method which is just developed bythe authors. It is found that the phonon and phason stresses near the crack tips exhibit inversesquare root singularities. The four complex stress functions characterizing the phonon and phasonfields are derived. Explicit expressions for the phonon and phason stress intensity factors, crackopening displacements and energy release rate are also presented.展开更多
The detailed atomic structure of quasicrystals has been an open problem for decades. Here we present a quasilattiee-conserved optimization method （quasi-OPT）, under particular quasiperiodic boundary conditions. As t...The detailed atomic structure of quasicrystals has been an open problem for decades. Here we present a quasilattiee-conserved optimization method （quasi-OPT）, under particular quasiperiodic boundary conditions. As the atomic coordinates are described by basic cells and quasilattices, we are able to maintain the self-similarity characteristics of qusicrystals with the atomic structure of the boundary region updated timely following the relaxing region. Exemplified with the study of decagonal Al-Co-Ni （d-Al-Co-Ni）, we propose a more stable atomic structure model based on Penrose quasilattice and our quasi-OPT simulations. In particular, rectangle-triangle ruIes are suggested for the local atomic structures of d-Al-Co-Ni quasicrystals.展开更多
On account of the Mori-Tanaka approach,the effective elastic performance of composites containing decagonal symmetric two-dimensional(2D)quasicrystal(QC)coatings is studied.Explicit expressions for the effective elast...On account of the Mori-Tanaka approach,the effective elastic performance of composites containing decagonal symmetric two-dimensional(2D)quasicrystal(QC)coatings is studied.Explicit expressions for the effective elastic constants of rare-earth QC reinforced magnesium-based composites are provided.Detailed discussion is presented on the effects of the volume fraction of the inclusions,the aspect ratio of the inclusions,the coating thickness,and the coating material parameters on the effective elastic constants of the composites.The results indicate that considering the coating increases the effective elastic constants of the composites to some extent.展开更多
This article represents a pioneering study centered on the corrosion kinetics of untreated and thermally processed mechano-synthesized Al_(x)Cr_(y)Ni_(z) two-dimensional decagonal quasicrystalline structure and crysta...This article represents a pioneering study centered on the corrosion kinetics of untreated and thermally processed mechano-synthesized Al_(x)Cr_(y)Ni_(z) two-dimensional decagonal quasicrystalline structure and crystalline approximants.It sheds light on the distinguished corrosion behavior of untreated and heat-treated mechano-synthesized Al_(72)Cr_(15)Ni_(13) and Al_(86)Cr_(12)Ni_(2)alloys,including a wide diversity of miscellaneous intermetallic phases.A comprehensive characterization was performed to analyze crystallographic structure and thermal characteristics of Al_(x)Cr_(y)Ni_(z) powder particles.Electrochemical evaluations of the mechano-synthesized Al_(72)Cr_(15)Ni_(13) and Al_(86)Cr_(12)Ni_(2) specimens and their heat-treated counterparts were conducted under cyclic potentiodynamic polarization tests with 0.1 mol/L Na_(2)SO_(4)(pH=2) and 3.5%NaCl(pH=8.5) electrolytes at room temperature,respectively.Al_(72)Cr_(15)Ni_(13) two-dimensional decagonal quasicrystalline phase was attained following 6 h mechanosynthesis and subsequent annealing treatment at 1035℃.There is no evidence of quasicrystal formation in the Al_(86)Cr_(12)Ni_(2) alloy system after 6 h mechano-synthesis and successive thermal processing at 445 and 570℃.In this study,we conducted the first investigation into electrochemical performance of both Al_(72)Cr_(15)Ni_(13) and Al_(86)Cr_(12)Ni_(2) intermetallics.Both Al_(72)Cr_(15)Ni_(13) and Al_(86)Cr_(12)Ni_(2) alloys develop a protective passive film in 0.1 mol/L Na_(2)SO_(4) electrolyte.It was determined that 6 h mechano-synthesized Al_(72)Cr_(15)Ni_(13) sample,subjected to annealing at 1035℃,stands out in the Al-Cr-Ni alloy systems for applications necessitating exceptional corrosion resistance,passivation behavior,and minimal susceptibility to pitting corrosion when compared to other tested counterparts.This alloy is characterized by a corrosion current density of 3.73μA/cm^(2) and a corrosion potential of-0.16 V(vs.Ag/AgCl),revealing a remarkably stable passive film up to a current density of 0.02 A/cm^(2) and a potential of 2.41 V(vs.Ag/AgCl)within 0.1 mol/L Na_(2)SO_(4) medium.Likewise,it exhibited a drastically diminished corrosion current density of 11.65μA/cm^(2) and a reduced corrosion potential of-0.27 V(vs.Ag/AgCl)within 3.5%NaCl electrolyte,attributed to the formation of two-dimensional decagonal quasicrystalline phase and hexagonalδ-Al_(3)Ni_(2) crystalline approximant at 1035℃.It also encompassed a re-passivation current density and potential of 50.35μA/cm^(2)and-0.04 V(vs.Ag/AgCl),respectively,within the latter solution.Its corrosion mechanism may be ascribed to a two-step surface precipitation process:initially,Al dissolves into a hydroxide,succeeded by the formation and precipitation of Al oxides,such as NaAlO_(2) and Al_(2)O_(3)·xH_(2)O.展开更多
High-entropy alloys(HEAs)contain multiple principal alloying elements,but usually with simple crystal structures.Quasicrystals are structurally complex phases,but are generally dominated by only one element.However,ne...High-entropy alloys(HEAs)contain multiple principal alloying elements,but usually with simple crystal structures.Quasicrystals are structurally complex phases,but are generally dominated by only one element.However,nearequiatomic high-entropy quasicrystals have rarely been reported because they are difficult to prepare experimentally and predict theoretically.Therefore,the preparation and crystal structures of near-equiatomic high-entropy quasicrystals have drawn much interest.We report a quinary decagonal quasicrystal(DQC)with near-equiatomic alloying elements in Al20Si20Mn20Fe20Ga20 melt-spun ribbons,which is the first to our knowledge.Meanwhile,the structural features of the DQC are characterized in detail.The configurational entropy of both the alloy and DQC satisfies the entropy-based criterion for HEAs,suggesting a high-entropy DQC.Our findings provide a new strategy to develop high-entropy quasicrystals.展开更多
Electron-diffraction pattern with 'tenfold rotational symmetry' of Al-Fe alloyphase is assumed to be produced by periodic structure. One 3D periodic structure is presentedbased on so-called C polyhedra. The st...Electron-diffraction pattern with 'tenfold rotational symmetry' of Al-Fe alloyphase is assumed to be produced by periodic structure. One 3D periodic structure is presentedbased on so-called C polyhedra. The structure can be used as atomic model to describethe Al-Fe alloy phase. The Fourier transform patterns of the model are in good agreementwith the corresponding electron-diffraction patterns. Several other models with' tenfold symmetry' Fourier transform patterns have briefly been mentioned.展开更多
文摘As a new structure of solid matter quasicrystal brings profound new ideas to the traditional condensed matter physics, its elastic equations are more complicated than that of traditional crystal. A contact problem of decagonal two? dimensional quasicrystal material under the action of a rigid flat die is solved satisfactorily by introducing displacement function and using Fourier analysis and dual integral equations theory, and the analytical expressions of stress and displacement fields of the contact problem are achieved. The results show that if the contact displacement is a constant in the contact zone, the vertical contact stress has order -1/2 singularity on the edge of contact zone, which provides the important mechanics parameter for contact deformation of the quasicrystal.
基金Supported by the National Natural Science Foundation of China under Grant No 11674102
文摘Double-well potentials are used for molecular dynamics simulation in monatomic systems. The potentials change as their parameters are adjusted, resulting in different structures. Of particular interest, we obtain decagonal and dodecagonal quasicrystals by simulations. We also verify the results and explain the formation of quasicrystals from the perspective of potential energy.
基金supported by the National Natural Science Foundation of China(No.11272121)Innovation Program of Shanghai Municipal Education Commission,China(No.12ZZ058)the Natural Sciences and Engineering Research Council of Canada
文摘In this work, an elegant method is proposed to derive the thermoelastic field in- duced by thermomechanical loadings in a decagonal quasicrystalline composite composed of an infinite matrix reinforced by an elliptical inclusion. The thermomechanical loadings include a uniform temperature change, remote uniform in-plane heat fluxes and remote uniform in-plane stresses. The corresponding boundary value problem is ultimately reduced to the solution of two independent sets of four coupled linear algebraic equations, each of which involves four complex constants characterizing the internal stress field. The solution demonstrates that a uniform tem- perature change and remote uniform stresses will induce an internal uniform stress field, and that uniform heat fluxes will result in a linearly distributed internal stress field within the elliptical inclusion. The induced uniform rigid body rotation within the inclusion is given explicitly.
文摘This investigation presents the Green functions for a decagonal quasicrystalline ma- terial with a parabolic boundary subject to a line force and a line dislocation by means of the complex variable method. The surface Green functions are treated as a special case, and the explicit expressions of displacements and hoop stress at the parabolic boundary are also given. Finally, the stresses and displacements induced by a phonon line force acting at the origin of the lower half-space are presented.
基金the National Natural Science Foundation of China(No.11272121)the Natural Sciences and Engineering Research Council of Canada(No.RGPIN-2017-03716115112)。
文摘We investigate the elastic field near the tip of an anticrack in a homogeneous decagonal quasicrystalline material subject to plane strain deformations. The phonon and phason stresses exhibit a square root singularity at the anticrack tip. Two realvalued phonon stress intensity factors and two real-valued phason stress intensity factors are introduced to scale four separate modes of deformation. We obtain four analytic functions which completely characterize the induced phonon and phason stresses as well as the displacement field. In particular, we derive a concise yet elegant representation of the anticrack contraction force.
文摘It is undeniable that wireless communication technology has become a very important component of modern society. One aspect of modern society in which application of wireless communication technologies has tremendous potential is in agricultural production. This is especially true in the area of sensing and transmission of relevant farming information such as weather, crop development, water quantity and quality, among others, which would allow farmers to make more accurate and timely farming decisions. A good example would be the application of wireless communication technology to transmit soil moisture data in real time to help farmers make irrigation scheduling decisions. Although many systems are commercially available for soil moisture monitoring, there are still many important factors, such as cost, limiting widespread adoption of this technology among growers. Our objective in this study was, therefore, to develop and test an affordable wireless communication system for monitoring soil moisture using Decagon EC-5 sensors. The new system uses Arduino-compatible microcontrollers and communication systems to sample and transmit values from four Decagon EC-5 soil moisture sensors. Developing the system required conducting lab calibrations for the EC-5 sensors for the microcontroller operating in either 10-bit or 12-bit analog-to-digital converter (ADC) resolution. The system was successfully tested in the field and reliably collected and transmitted data from a wheat field for more than two months.
基金the National Natural Science Foundation of China (Nos. 11572289,1171407,11702252,and 11902293)the China Postdoctoral Science Foundation (No. 2019M652563)。
文摘The interface crack problems in the two-dimensional(2D)decagonal quasicrystal(QC)coating are theoretically and numerically investigated with a displacement discontinuity method.The 2D general solution is obtained based on the potential theory.An analogy method is proposed based on the relationship between the general solutions for 2D decagonal and one-dimensional(1D)hexagonal QCs.According to the analogy method,the fundamental solutions of concentrated point phonon displacement discontinuities are obtained on the interface.By using the superposition principle,the hypersingular boundary integral-differential equations in terms of displacement discontinuities are determined for a line interface crack.Further,Green’s functions are found for uniform displacement discontinuities on a line element.The oscillatory singularity near a crack tip is eliminated by adopting the Gaussian distribution to approximate the delta function.The stress intensity factors(SIFs)with ordinary singularity and the energy release rate(ERR)are derived.Finally,a boundary element method is put forward to investigate the effects of different factors on the fracture.
基金Project supported by the National Excellent Young Scholar Science Fund of China(No.10125209)the Teaching and Research Award Fuud for Outstanding Young Teachers in High Education Institutions of the Ministry of Education of China
文摘A decagonal quasicrystal, which is weakened by an arc-shaped crackpenetrating through the solid in the period direction, and which is subjected to remote uniformphonon stresses, is investigated by applying the complex variable method which is just developed bythe authors. It is found that the phonon and phason stresses near the crack tips exhibit inversesquare root singularities. The four complex stress functions characterizing the phonon and phasonfields are derived. Explicit expressions for the phonon and phason stress intensity factors, crackopening displacements and energy release rate are also presented.
基金Supported by the National Natural Science Foundation of China under Grant No 11174082
文摘The detailed atomic structure of quasicrystals has been an open problem for decades. Here we present a quasilattiee-conserved optimization method （quasi-OPT）, under particular quasiperiodic boundary conditions. As the atomic coordinates are described by basic cells and quasilattices, we are able to maintain the self-similarity characteristics of qusicrystals with the atomic structure of the boundary region updated timely following the relaxing region. Exemplified with the study of decagonal Al-Co-Ni （d-Al-Co-Ni）, we propose a more stable atomic structure model based on Penrose quasilattice and our quasi-OPT simulations. In particular, rectangle-triangle ruIes are suggested for the local atomic structures of d-Al-Co-Ni quasicrystals.
基金Project supported by the Inner Mongolia Natural Science Foundation of China(No.2021MS01013)。
文摘On account of the Mori-Tanaka approach,the effective elastic performance of composites containing decagonal symmetric two-dimensional(2D)quasicrystal(QC)coatings is studied.Explicit expressions for the effective elastic constants of rare-earth QC reinforced magnesium-based composites are provided.Detailed discussion is presented on the effects of the volume fraction of the inclusions,the aspect ratio of the inclusions,the coating thickness,and the coating material parameters on the effective elastic constants of the composites.The results indicate that considering the coating increases the effective elastic constants of the composites to some extent.
文摘This article represents a pioneering study centered on the corrosion kinetics of untreated and thermally processed mechano-synthesized Al_(x)Cr_(y)Ni_(z) two-dimensional decagonal quasicrystalline structure and crystalline approximants.It sheds light on the distinguished corrosion behavior of untreated and heat-treated mechano-synthesized Al_(72)Cr_(15)Ni_(13) and Al_(86)Cr_(12)Ni_(2)alloys,including a wide diversity of miscellaneous intermetallic phases.A comprehensive characterization was performed to analyze crystallographic structure and thermal characteristics of Al_(x)Cr_(y)Ni_(z) powder particles.Electrochemical evaluations of the mechano-synthesized Al_(72)Cr_(15)Ni_(13) and Al_(86)Cr_(12)Ni_(2) specimens and their heat-treated counterparts were conducted under cyclic potentiodynamic polarization tests with 0.1 mol/L Na_(2)SO_(4)(pH=2) and 3.5%NaCl(pH=8.5) electrolytes at room temperature,respectively.Al_(72)Cr_(15)Ni_(13) two-dimensional decagonal quasicrystalline phase was attained following 6 h mechanosynthesis and subsequent annealing treatment at 1035℃.There is no evidence of quasicrystal formation in the Al_(86)Cr_(12)Ni_(2) alloy system after 6 h mechano-synthesis and successive thermal processing at 445 and 570℃.In this study,we conducted the first investigation into electrochemical performance of both Al_(72)Cr_(15)Ni_(13) and Al_(86)Cr_(12)Ni_(2) intermetallics.Both Al_(72)Cr_(15)Ni_(13) and Al_(86)Cr_(12)Ni_(2) alloys develop a protective passive film in 0.1 mol/L Na_(2)SO_(4) electrolyte.It was determined that 6 h mechano-synthesized Al_(72)Cr_(15)Ni_(13) sample,subjected to annealing at 1035℃,stands out in the Al-Cr-Ni alloy systems for applications necessitating exceptional corrosion resistance,passivation behavior,and minimal susceptibility to pitting corrosion when compared to other tested counterparts.This alloy is characterized by a corrosion current density of 3.73μA/cm^(2) and a corrosion potential of-0.16 V(vs.Ag/AgCl),revealing a remarkably stable passive film up to a current density of 0.02 A/cm^(2) and a potential of 2.41 V(vs.Ag/AgCl)within 0.1 mol/L Na_(2)SO_(4) medium.Likewise,it exhibited a drastically diminished corrosion current density of 11.65μA/cm^(2) and a reduced corrosion potential of-0.27 V(vs.Ag/AgCl)within 3.5%NaCl electrolyte,attributed to the formation of two-dimensional decagonal quasicrystalline phase and hexagonalδ-Al_(3)Ni_(2) crystalline approximant at 1035℃.It also encompassed a re-passivation current density and potential of 50.35μA/cm^(2)and-0.04 V(vs.Ag/AgCl),respectively,within the latter solution.Its corrosion mechanism may be ascribed to a two-step surface precipitation process:initially,Al dissolves into a hydroxide,succeeded by the formation and precipitation of Al oxides,such as NaAlO_(2) and Al_(2)O_(3)·xH_(2)O.
基金the National Natural Science Foundation of China(51871015 and 51471024)the Selfdetermined Project of the State Key Laboratory for Advanced Metals and Materials(2016Z-13)。
文摘High-entropy alloys(HEAs)contain multiple principal alloying elements,but usually with simple crystal structures.Quasicrystals are structurally complex phases,but are generally dominated by only one element.However,nearequiatomic high-entropy quasicrystals have rarely been reported because they are difficult to prepare experimentally and predict theoretically.Therefore,the preparation and crystal structures of near-equiatomic high-entropy quasicrystals have drawn much interest.We report a quinary decagonal quasicrystal(DQC)with near-equiatomic alloying elements in Al20Si20Mn20Fe20Ga20 melt-spun ribbons,which is the first to our knowledge.Meanwhile,the structural features of the DQC are characterized in detail.The configurational entropy of both the alloy and DQC satisfies the entropy-based criterion for HEAs,suggesting a high-entropy DQC.Our findings provide a new strategy to develop high-entropy quasicrystals.
文摘Electron-diffraction pattern with 'tenfold rotational symmetry' of Al-Fe alloyphase is assumed to be produced by periodic structure. One 3D periodic structure is presentedbased on so-called C polyhedra. The structure can be used as atomic model to describethe Al-Fe alloy phase. The Fourier transform patterns of the model are in good agreementwith the corresponding electron-diffraction patterns. Several other models with' tenfold symmetry' Fourier transform patterns have briefly been mentioned.
