The phase behaviours of diblock copolymers under cylindrical confinement are studied in two-dimensional space by using the self-consistent field theory. Several phase parameters are adjusted to investigate the cylindr...The phase behaviours of diblock copolymers under cylindrical confinement are studied in two-dimensional space by using the self-consistent field theory. Several phase parameters are adjusted to investigate the cylindrical-confinement-induced phase behaviours of diblock copolymers. A series of lamella-cylinder mixture phases, such as the mixture of broken-lamellae and cylinders and the mixture of square-lamellae and cylinders, are observed by varying the phase parameters, in which the behaviours of these mixture phases are discussed in the corresponding phase diagrams. Furthermore, the free energies of these mixture phases are investigated to illustrate their evolution processes. Our results are compared with the available observations from the experiments and simulations respectively, and they are in good agreement and provide an insight into the phase behaviours under cylindrical confinement.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
The site occupations of the alloying elements of O phase in Ti 2AlNb based intermetallics are clarified. The ordering behaviours of the O phase in Ti y Al z Nb( y ≥ 25%, mole fraction) orthorhombic alloys are also in...The site occupations of the alloying elements of O phase in Ti 2AlNb based intermetallics are clarified. The ordering behaviours of the O phase in Ti y Al z Nb( y ≥ 25%, mole fraction) orthorhombic alloys are also investigated with a Bragg Williams model. In the temperature range where the O phases exist, the order parameters change with the alloy composition and temperature continuously, and the first order transition character is very "展开更多
This paper provides an investigation of the phase transition and spalling characteristic induced during shock loading and unloading in the pure iron and the FeMnNi alloy. The impact for the pure iron is symmetric and ...This paper provides an investigation of the phase transition and spalling characteristic induced during shock loading and unloading in the pure iron and the FeMnNi alloy. The impact for the pure iron is symmetric and with the same-thickness for both the flyer and the target plate. It is found that an abnormal multiple spalling happens in the pure iron sample as the pressure exceeds the α- ε transition threshold of 13 GPa. In the symmetric and same-thickness impact and reverse impact experiments of the FeMnNi alloy, two abnormal tension regions occur when the pressure exceeds the α - ε transition threshold of 6.3 GPa, and the reverse phase transition s - ~ begins below 4.2 GP. The experimental process is simulated successfully from the non-equilibrium mixture phase and Boettger＇s model. Such abnormal spalling phenomena are believed to relate to the shocked α - ε phase transition. The possible reasons for the abnormal multiple spalling, which occurs during the symmetric and same-thickness impact experiments of pure iron and FeMnNi alloy, are discussed.展开更多
The experiments show that the middle phase microemulsions can form in tetradecane pyridinium bromide/alcohol/n-heptane/brine systems. The phase behaviour was investigated by using concentration scanning and interfacia...The experiments show that the middle phase microemulsions can form in tetradecane pyridinium bromide/alcohol/n-heptane/brine systems. The phase behaviour was investigated by using concentration scanning and interfacial tension methods. The formation and characteristics of the middle phase microemulsions are affected obviously by the concentrations of TPB from 0.5 % to 6.0 %, the concentrations of n-butanol from 2.0 to 7.0 % and the n-alcohols from C3H7OH to C5H11 OH. The difference between systems with TPB and sodium dodecyl sulfonate (AS) is also discussed. Some rules are worked out.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 20574052 and 20774066)the Program for New Century Excellent Talents in University, China (Grant No. NCET-05-0538)the Natural Science Foundation of Zhejiang Province, China (Grant Nos. R404047, Y4090174, and Y405553)
文摘The phase behaviours of diblock copolymers under cylindrical confinement are studied in two-dimensional space by using the self-consistent field theory. Several phase parameters are adjusted to investigate the cylindrical-confinement-induced phase behaviours of diblock copolymers. A series of lamella-cylinder mixture phases, such as the mixture of broken-lamellae and cylinders and the mixture of square-lamellae and cylinders, are observed by varying the phase parameters, in which the behaviours of these mixture phases are discussed in the corresponding phase diagrams. Furthermore, the free energies of these mixture phases are investigated to illustrate their evolution processes. Our results are compared with the available observations from the experiments and simulations respectively, and they are in good agreement and provide an insight into the phase behaviours under cylindrical confinement.
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.
文摘The site occupations of the alloying elements of O phase in Ti 2AlNb based intermetallics are clarified. The ordering behaviours of the O phase in Ti y Al z Nb( y ≥ 25%, mole fraction) orthorhombic alloys are also investigated with a Bragg Williams model. In the temperature range where the O phases exist, the order parameters change with the alloy composition and temperature continuously, and the first order transition character is very "
基金Project supported by the National Science Foundations of China (Grant Nos. 10776032 and 10902102)Science Foundation of China Academy of Engineering Physics (Grant Nos. 20060104 and 2009B0201014)
文摘This paper provides an investigation of the phase transition and spalling characteristic induced during shock loading and unloading in the pure iron and the FeMnNi alloy. The impact for the pure iron is symmetric and with the same-thickness for both the flyer and the target plate. It is found that an abnormal multiple spalling happens in the pure iron sample as the pressure exceeds the α- ε transition threshold of 13 GPa. In the symmetric and same-thickness impact and reverse impact experiments of the FeMnNi alloy, two abnormal tension regions occur when the pressure exceeds the α - ε transition threshold of 6.3 GPa, and the reverse phase transition s - ~ begins below 4.2 GP. The experimental process is simulated successfully from the non-equilibrium mixture phase and Boettger＇s model. Such abnormal spalling phenomena are believed to relate to the shocked α - ε phase transition. The possible reasons for the abnormal multiple spalling, which occurs during the symmetric and same-thickness impact experiments of pure iron and FeMnNi alloy, are discussed.
文摘The experiments show that the middle phase microemulsions can form in tetradecane pyridinium bromide/alcohol/n-heptane/brine systems. The phase behaviour was investigated by using concentration scanning and interfacial tension methods. The formation and characteristics of the middle phase microemulsions are affected obviously by the concentrations of TPB from 0.5 % to 6.0 %, the concentrations of n-butanol from 2.0 to 7.0 % and the n-alcohols from C3H7OH to C5H11 OH. The difference between systems with TPB and sodium dodecyl sulfonate (AS) is also discussed. Some rules are worked out.
