A set of thermodynamic descriptions of the temary compounds （mainly α-CulnSe2, δ-CulnSe2, Culn3Se5 and CulnsSe8） in the Cu-In-Se system was established by adopting sub-lattice model. The model parameters are caref...A set of thermodynamic descriptions of the temary compounds （mainly α-CulnSe2, δ-CulnSe2, Culn3Se5 and CulnsSe8） in the Cu-In-Se system was established by adopting sub-lattice model. The model parameters are carefully evaluated by integrating the experimental data of thermodynamic properties, phase equilibrium and theoretical calculation of formation energies of different point defects. The evaluated Gibbs energies of the compounds reasonably agree with that estimated from EMF experiment and ab initio calculation. The calculated phase relationships in the Cu-In-Se system are in accord with the experimental phase diagrams. The obtained standard enthalpy of formation of CulnSe2 is close to that reported in the literatures.展开更多
Molecular dynamics simulation of uniaxial tension along [001] has been performed to study the influence of various surface defects on the initiation of plastic deformation and fracture of γ-TiAl single crystals.The r...Molecular dynamics simulation of uniaxial tension along [001] has been performed to study the influence of various surface defects on the initiation of plastic deformation and fracture of γ-TiAl single crystals.The results indicate that brittle fracture occurs in perfect bulk; surfaces and edges will be detrimental to the strength of materials and provide dislocation nucleation site. The defects on surfaces and edges cause further weakening with various effects depending on defect type, size, position and orientation,while the edge dimples are the most influential. For γ-TiAl rods with surface dimples, dislocations nucleate from an edge of the rod when dimples are small, dimple dislocation nucleation occurs only when the dimples are larger than a strain rate dependent critical size. The dislocations nucleated upon [001]tension are super dislocations with Burger vectors 〈011] or 1/2 〈 112] containing four 1/6 〈 112 〉 partials. The effects of surface scratches are orientation and shape sensitive. Scratches parallel to the loading direction have little influence, while sharp ones perpendicular to the loading direction may cause crack and thus should be avoided. This simulation also shows that, any type of surface defect would lower strength,and cause crack in some cases. But some may facilitate dislocation nucleation and improve ductility of TiAl if well controlled.展开更多
Equilibrium equation of point defects in Ll_2 type intermetallic compounds was established to calculate the relations of the concentration of antisite defects and vacancies and bulk composi- tion in Ni_3Al.The examina...Equilibrium equation of point defects in Ll_2 type intermetallic compounds was established to calculate the relations of the concentration of antisite defects and vacancies and bulk composi- tion in Ni_3Al.The examination of temperature effects on the point defects cleared up the mis. understanding of the properties of the“constitutional point defects”in Ni_3Al.展开更多
Formation of nuclear tracks in solids has been described as a thermal spike as well as a Coulomb explo- sion spike.Here,formation of nuclear tracks is described as a compound spike including partial roles of both ther...Formation of nuclear tracks in solids has been described as a thermal spike as well as a Coulomb explo- sion spike.Here,formation of nuclear tracks is described as a compound spike including partial roles of both thermal and Coulomb explosion spikes in track formation.Fractional roles of both spikes depend on atomic and electronic structure of a track detector and deposited energy density in the track detector by the incident charged particle.Be- havior of the cylindrical zone along the path of the incident particle is described mathematically in terms of bulk and individual atomic flow or movement.Defect structure of the latent nuclear tracks is described and conditions of con- tinuity and discontinuity of latent tracks are evaluated and discussed.This paper includes mathematical description, analysis and evaluation of the nuclear track formation issue in the light of published experimental and theoretical re- sults,which are useful for users of nuclear track detection technique and researchers involved in ion beam induced materials modification and ions implantation in semiconductors.展开更多
文摘A set of thermodynamic descriptions of the temary compounds （mainly α-CulnSe2, δ-CulnSe2, Culn3Se5 and CulnsSe8） in the Cu-In-Se system was established by adopting sub-lattice model. The model parameters are carefully evaluated by integrating the experimental data of thermodynamic properties, phase equilibrium and theoretical calculation of formation energies of different point defects. The evaluated Gibbs energies of the compounds reasonably agree with that estimated from EMF experiment and ab initio calculation. The calculated phase relationships in the Cu-In-Se system are in accord with the experimental phase diagrams. The obtained standard enthalpy of formation of CulnSe2 is close to that reported in the literatures.
基金supported by the National Basic Research Program of China (No.2011CB606404)the National Natural Science Foundation of China (No.51171195)the GM Research Project
文摘Molecular dynamics simulation of uniaxial tension along [001] has been performed to study the influence of various surface defects on the initiation of plastic deformation and fracture of γ-TiAl single crystals.The results indicate that brittle fracture occurs in perfect bulk; surfaces and edges will be detrimental to the strength of materials and provide dislocation nucleation site. The defects on surfaces and edges cause further weakening with various effects depending on defect type, size, position and orientation,while the edge dimples are the most influential. For γ-TiAl rods with surface dimples, dislocations nucleate from an edge of the rod when dimples are small, dimple dislocation nucleation occurs only when the dimples are larger than a strain rate dependent critical size. The dislocations nucleated upon [001]tension are super dislocations with Burger vectors 〈011] or 1/2 〈 112] containing four 1/6 〈 112 〉 partials. The effects of surface scratches are orientation and shape sensitive. Scratches parallel to the loading direction have little influence, while sharp ones perpendicular to the loading direction may cause crack and thus should be avoided. This simulation also shows that, any type of surface defect would lower strength,and cause crack in some cases. But some may facilitate dislocation nucleation and improve ductility of TiAl if well controlled.
文摘Equilibrium equation of point defects in Ll_2 type intermetallic compounds was established to calculate the relations of the concentration of antisite defects and vacancies and bulk composi- tion in Ni_3Al.The examination of temperature effects on the point defects cleared up the mis. understanding of the properties of the“constitutional point defects”in Ni_3Al.
文摘Formation of nuclear tracks in solids has been described as a thermal spike as well as a Coulomb explo- sion spike.Here,formation of nuclear tracks is described as a compound spike including partial roles of both thermal and Coulomb explosion spikes in track formation.Fractional roles of both spikes depend on atomic and electronic structure of a track detector and deposited energy density in the track detector by the incident charged particle.Be- havior of the cylindrical zone along the path of the incident particle is described mathematically in terms of bulk and individual atomic flow or movement.Defect structure of the latent nuclear tracks is described and conditions of con- tinuity and discontinuity of latent tracks are evaluated and discussed.This paper includes mathematical description, analysis and evaluation of the nuclear track formation issue in the light of published experimental and theoretical re- sults,which are useful for users of nuclear track detection technique and researchers involved in ion beam induced materials modification and ions implantation in semiconductors.
