The structures of Al 14 Cu 12 clusters were optimized by B3LYP method and the six geometries ground states were obtained. Al 71 Cu 29 alloy melt has been investigated using X ray diffractometry at 700 ℃. The experime...The structures of Al 14 Cu 12 clusters were optimized by B3LYP method and the six geometries ground states were obtained. Al 71 Cu 29 alloy melt has been investigated using X ray diffractometry at 700 ℃. The experimental data were compared with calculated results to find the relation between the structures of Al Cu clusters and melt structure. It is shown that there exists a strong interaction between Al and Cu atoms. The bond length in some geometries is very close to the experimental atomic distance. Such optimized geometries have close correlation with the liquid structure of Al Cu alloy.展开更多
The study investigates the effects of pre-strain on the bake hardenability and precipitation behavior of Al-Mg-Si automotive body sheets. The scanning electron microscopy, transmission electron microscopy, tensile tes...The study investigates the effects of pre-strain on the bake hardenability and precipitation behavior of Al-Mg-Si automotive body sheets. The scanning electron microscopy, transmission electron microscopy, tensile test, Vickers hardness test, and differential scanning calorimetry were conducted for the purpose. It was found that the pre-strain treatment partially inhibits the natural aging hardening effect but cannot completely eliminate it. The pre-straining significantly enhances the bake hardening effect, with the 5% pre-strain sample showing the highest increase in yield strength and hardness. The formation of fine β" precipitates and dislocation structures contribute to the observed strengthening. Additionally, the study highlights the importance of optimizing pre-strain levels to achieve the best balance between strength and ductility in bake-hardened aluminum alloys.展开更多
Al2-Al40 clusters were studied by means of the all-electron DFT method. The properties of the aluminum clusters including binding energy, the second difference in energy, HOMO-LUMO gap, especially fragmentation energi...Al2-Al40 clusters were studied by means of the all-electron DFT method. The properties of the aluminum clusters including binding energy, the second difference in energy, HOMO-LUMO gap, especially fragmentation energies and ionization potentials, were analyzed. The main products from the dissociations of aluminum cluster ions are shown to be Al ＋ Al^＋n-1 for the larger clusters, and Al^＋ ＋Aln-1 for the smaller ones. And, the calculated ionization potentials are consistent with the experiment data.展开更多
Using first-principles pseudo-potential plane wave method, the energetics, geometrical and electronic structures of three Al13I cluster isomers were calculated. The calculation results of the binding energy indicate A...Using first-principles pseudo-potential plane wave method, the energetics, geometrical and electronic structures of three Al13I cluster isomers were calculated. The calculation results of the binding energy indicate Al13I cluster is more stable than Al13 cluster although its electrons are not a magic number as in Alia cluster, and among Al13I cluster isomers the ＂Bridge＂ structure is the most stable, the second is the ＂Ontop＂ structure, and the worst is the ＂Hollow＂ structure. By analyzing the geometrical structures of Al13I cluster isomers, it is found that after I atom and Al13 cluster combine the geometrical structures of Al13 moieties are changed besides Al13I Hollow cluster, in which the Alia moiety is still a regular icosahedron. For Al13I Ontop cluster, the Al13 moiety has a shrinking trend to I, whereas in Al13I Bridge cluster it is distorted. Mulliken population analysis shows for the interaction of electrons between Al-I atoms in Al13I cluster not only there exists an ionic bonding but there is a covalent bonding. Part of electrons in the Alia cluster transfer to I as Al13 cluster and I atom combine. The order of the strength of covalent bonding between Al13 moiety and I in Al13I cluster isomers is Al13IBridge〉Al13IHollow〉Al13I Ontop. Further analysis of electric structures of Al13 and Al13I clusters indicates a higher stability of Al13I cluster than Al13 cluster can be attributed to the s-p hybridization of 3s and 3p electrons of Al in Al13 moiety induced by 1 doped, which leads to fewer electrons N（EF） at EF in Al13I and a larger energy gap △EH-L between HOMO and LUMO levels in Al13I cluster. The distinguish of structural stability of Al13I cluster isomers mainly originates from their different magnitudes .in decrease of N（EF） and increase of △EH-L relative to Al13 cluster. The fewest N（EF） and the largest △EH-L are responsible for the high stability of Al13I Bridge cluster.展开更多
Starting from the configuration full optimized by Genetic Algorithm (GA), the melting behaviors of Binary Ni 13-xAl x(x=0 to 13) clusters have been investigated by Monte Carlo (MC) simulations with Metropolis algorith...Starting from the configuration full optimized by Genetic Algorithm (GA), the melting behaviors of Binary Ni 13-xAl x(x=0 to 13) clusters have been investigated by Monte Carlo (MC) simulations with Metropolis algorithm with a n-body Gupta potential. In contrast to bulk, these clusters have smeared first order transitions occurring over a range of temperature. The melting temperature T m calculated from Lindemann’s criterion vary drastically with concentrations x. For most clusters studied, the average energy per atom E, the relative root-mean-square (rms) bond length fluchuation δ and the heat capacity C per atom related to the energy fluctuation of the system change with temperature in the transition region in manners differing from LJ and alkali metal clusters. For Ni 12Al, Ni 7Al 6, Ni 6Al 7, Ni 5Al 8 clusters, there are behaviors characteristic of magic number in C, which do not exist in the pure TM clusters.展开更多
The evolution of configurations of Aln (n=3,4,6,13,19) clusters were investigated using linear synchronous transit (LST) method. The stable structures of Al3, Al4, Al6, Al13, Al19 clusters were confirmed to be triangl...The evolution of configurations of Aln (n=3,4,6,13,19) clusters were investigated using linear synchronous transit (LST) method. The stable structures of Al3, Al4, Al6, Al13, Al19 clusters were confirmed to be triangle, rhombus, octahedron, icosahedron and double icosahedron, respectively. For Al6 and Al19 clusters there are metastable structures of parallelogram and octahedron, respectively, whereas in the Al3, Al4 and Al13 clusters, no metastable configuration are validated. A large energy gap and a low energy barrier between the parallelogram and the octahedron of the Al6 cluster indicate the transformation from its metastable configuration to stable octahedron to be rather easy. By contrast, a small energy gap and a high energy barrier between the stable and metastable structures of Al19 cluster mean its configuration evolution from the octahedron to the double icosahedron occurs hardly, therefore the metastable octahedron configuration of Al19 cluster can be extensively detected in experiments and simulations.展开更多
Ordering and atom clustering in aging binary Al-Li alloy has been investigated by computer simulation through calculating the long range order (Iro.) parameter and composition deviation order parameter from single-sit...Ordering and atom clustering in aging binary Al-Li alloy has been investigated by computer simulation through calculating the long range order (Iro.) parameter and composition deviation order parameter from single-site occupation probabilities of Li atom. The results show that when the alloy lies in metastable region in the phase diagram ordering and atom clustering occur simultaneously. As the composition of the alloy increases ordering occurs earlier than atom clustering gradually. When the alloy lies in instable region atom clustering takes place after the congruent ordering completes. It has also been found that the incubation period of the phase transformation is shortened as the composition increases.展开更多
Based on the density functional theory with generalized gradient approximation, the stable geometrical structures of one or more CO molecules adsorbed on the Al6Si cluster are investigated and the corresponding adsorp...Based on the density functional theory with generalized gradient approximation, the stable geometrical structures of one or more CO molecules adsorbed on the Al6Si cluster are investigated and the corresponding adsorption energies are also calculated. It is found that the cluster Al6Si can adsorb six CO molecules. The thermal stability of the（CO）6@Al6Si complexes is examined using the atom centered density matrix propagation molecular dynamics calculations at 373 K. The results show that two isomers of Al6Si cluster can solidly adsorb six CO molecules, and the other isomer adsorbs four ones. Therefore, the Al6Si cluster is a promising candidate for eliminating CO effectively.展开更多
The geometry and electronic topology properties of Mg/Al hydrotalcite cluster models were comparatively investigated by means of density functional theory at GGA/DND levels.The results suggested that cluster model con...The geometry and electronic topology properties of Mg/Al hydrotalcite cluster models were comparatively investigated by means of density functional theory at GGA/DND levels.The results suggested that cluster model containing seven octahedral cations was the smallest size to be employed to simulate other properties.The fact that the n＋ charge of cluster models containing n aluminum atoms can reflect electronic properties of anionic clay layer sheet.The bond lengths of clusters can be modified by terminating with or without OH-/H2O groups in terms of principle of bond order conservation.展开更多
By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L...By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L12 Al3Ti-base intermetallic compound. The results are presented using the density of states (DOS) and one-electron properties, such as relative binding tendency between the atom and the model cluster, and hybrid bonding tendency between the alloying element and the host atoms. By comparing the four models of Ti4Al14X cluster, the effect of the Fe, Ni or Cu atom on the physical properties of Al3Ti-based L12 intermetallic compounds is analyzed. The results indicate that the addition of the Fe, Ni or Cu atom intensifies the relative binding tendency between Ti atom and Ti4Al14X cluster. It was found that the Fermi level (EF) lies in a maximum in the DOS for Ti4Al14Al cluster; on the contrary, the EF comes near a minimum tn the DOS for Ti4Al14X (X=Fe, Ni and Cu) cluster. Thus the L12 crystal structure for binary Al3Ti alloy is unstable, and the addition of the Fe, Ni or Cu atom to Al3Ti is benefical to stabilize L12 crystal structure. The calculation also shows that the Fe, Ni or Cu atom strengthens the hybrid bonding tendency between the central atom and the host atoms for Ti4Al14X cluster and thereby may lead to the constriction of the lattice of Al3Ti-base intermetallic compounds.展开更多
文摘The structures of Al 14 Cu 12 clusters were optimized by B3LYP method and the six geometries ground states were obtained. Al 71 Cu 29 alloy melt has been investigated using X ray diffractometry at 700 ℃. The experimental data were compared with calculated results to find the relation between the structures of Al Cu clusters and melt structure. It is shown that there exists a strong interaction between Al and Cu atoms. The bond length in some geometries is very close to the experimental atomic distance. Such optimized geometries have close correlation with the liquid structure of Al Cu alloy.
文摘The study investigates the effects of pre-strain on the bake hardenability and precipitation behavior of Al-Mg-Si automotive body sheets. The scanning electron microscopy, transmission electron microscopy, tensile test, Vickers hardness test, and differential scanning calorimetry were conducted for the purpose. It was found that the pre-strain treatment partially inhibits the natural aging hardening effect but cannot completely eliminate it. The pre-straining significantly enhances the bake hardening effect, with the 5% pre-strain sample showing the highest increase in yield strength and hardness. The formation of fine β" precipitates and dislocation structures contribute to the observed strengthening. Additionally, the study highlights the importance of optimizing pre-strain levels to achieve the best balance between strength and ductility in bake-hardened aluminum alloys.
基金Supported by the National Natural Science Foundation of China(Nos.20773047 and 20473030)
文摘Al2-Al40 clusters were studied by means of the all-electron DFT method. The properties of the aluminum clusters including binding energy, the second difference in energy, HOMO-LUMO gap, especially fragmentation energies and ionization potentials, were analyzed. The main products from the dissociations of aluminum cluster ions are shown to be Al ＋ Al^＋n-1 for the larger clusters, and Al^＋ ＋Aln-1 for the smaller ones. And, the calculated ionization potentials are consistent with the experiment data.
基金This work was supported by the Science & Technology Major Programs of Ministry of Education of China (No. 101139)
文摘Using first-principles pseudo-potential plane wave method, the energetics, geometrical and electronic structures of three Al13I cluster isomers were calculated. The calculation results of the binding energy indicate Al13I cluster is more stable than Al13 cluster although its electrons are not a magic number as in Alia cluster, and among Al13I cluster isomers the ＂Bridge＂ structure is the most stable, the second is the ＂Ontop＂ structure, and the worst is the ＂Hollow＂ structure. By analyzing the geometrical structures of Al13I cluster isomers, it is found that after I atom and Al13 cluster combine the geometrical structures of Al13 moieties are changed besides Al13I Hollow cluster, in which the Alia moiety is still a regular icosahedron. For Al13I Ontop cluster, the Al13 moiety has a shrinking trend to I, whereas in Al13I Bridge cluster it is distorted. Mulliken population analysis shows for the interaction of electrons between Al-I atoms in Al13I cluster not only there exists an ionic bonding but there is a covalent bonding. Part of electrons in the Alia cluster transfer to I as Al13 cluster and I atom combine. The order of the strength of covalent bonding between Al13 moiety and I in Al13I cluster isomers is Al13IBridge〉Al13IHollow〉Al13I Ontop. Further analysis of electric structures of Al13 and Al13I clusters indicates a higher stability of Al13I cluster than Al13 cluster can be attributed to the s-p hybridization of 3s and 3p electrons of Al in Al13 moiety induced by 1 doped, which leads to fewer electrons N（EF） at EF in Al13I and a larger energy gap △EH-L between HOMO and LUMO levels in Al13I cluster. The distinguish of structural stability of Al13I cluster isomers mainly originates from their different magnitudes .in decrease of N（EF） and increase of △EH-L relative to Al13 cluster. The fewest N（EF） and the largest △EH-L are responsible for the high stability of Al13I Bridge cluster.
基金supported by the nationa1 Natural Science Foundation of china(No.2980210).
文摘Starting from the configuration full optimized by Genetic Algorithm (GA), the melting behaviors of Binary Ni 13-xAl x(x=0 to 13) clusters have been investigated by Monte Carlo (MC) simulations with Metropolis algorithm with a n-body Gupta potential. In contrast to bulk, these clusters have smeared first order transitions occurring over a range of temperature. The melting temperature T m calculated from Lindemann’s criterion vary drastically with concentrations x. For most clusters studied, the average energy per atom E, the relative root-mean-square (rms) bond length fluchuation δ and the heat capacity C per atom related to the energy fluctuation of the system change with temperature in the transition region in manners differing from LJ and alkali metal clusters. For Ni 12Al, Ni 7Al 6, Ni 6Al 7, Ni 5Al 8 clusters, there are behaviors characteristic of magic number in C, which do not exist in the pure TM clusters.
基金Prqject(104139) supported by the Ministry of Education of China Project(03-Y3069) supported by the Hunan Province Natural Science Fund
文摘The evolution of configurations of Aln (n=3,4,6,13,19) clusters were investigated using linear synchronous transit (LST) method. The stable structures of Al3, Al4, Al6, Al13, Al19 clusters were confirmed to be triangle, rhombus, octahedron, icosahedron and double icosahedron, respectively. For Al6 and Al19 clusters there are metastable structures of parallelogram and octahedron, respectively, whereas in the Al3, Al4 and Al13 clusters, no metastable configuration are validated. A large energy gap and a low energy barrier between the parallelogram and the octahedron of the Al6 cluster indicate the transformation from its metastable configuration to stable octahedron to be rather easy. By contrast, a small energy gap and a high energy barrier between the stable and metastable structures of Al19 cluster mean its configuration evolution from the octahedron to the double icosahedron occurs hardly, therefore the metastable octahedron configuration of Al19 cluster can be extensively detected in experiments and simulations.
文摘Ordering and atom clustering in aging binary Al-Li alloy has been investigated by computer simulation through calculating the long range order (Iro.) parameter and composition deviation order parameter from single-site occupation probabilities of Li atom. The results show that when the alloy lies in metastable region in the phase diagram ordering and atom clustering occur simultaneously. As the composition of the alloy increases ordering occurs earlier than atom clustering gradually. When the alloy lies in instable region atom clustering takes place after the congruent ordering completes. It has also been found that the incubation period of the phase transformation is shortened as the composition increases.
基金supported by the National Natural Science Foundation of China(Nos.NSFC-11574125 and NSFC-11374132)the Taishan Scholar Project of Shandong Province(ts201511055)
文摘Based on the density functional theory with generalized gradient approximation, the stable geometrical structures of one or more CO molecules adsorbed on the Al6Si cluster are investigated and the corresponding adsorption energies are also calculated. It is found that the cluster Al6Si can adsorb six CO molecules. The thermal stability of the（CO）6@Al6Si complexes is examined using the atom centered density matrix propagation molecular dynamics calculations at 373 K. The results show that two isomers of Al6Si cluster can solidly adsorb six CO molecules, and the other isomer adsorbs four ones. Therefore, the Al6Si cluster is a promising candidate for eliminating CO effectively.
基金supported by China University of Petroleum (East China) (grant 09CX04045A)
文摘The geometry and electronic topology properties of Mg/Al hydrotalcite cluster models were comparatively investigated by means of density functional theory at GGA/DND levels.The results suggested that cluster model containing seven octahedral cations was the smallest size to be employed to simulate other properties.The fact that the n＋ charge of cluster models containing n aluminum atoms can reflect electronic properties of anionic clay layer sheet.The bond lengths of clusters can be modified by terminating with or without OH-/H2O groups in terms of principle of bond order conservation.
文摘By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L12 Al3Ti-base intermetallic compound. The results are presented using the density of states (DOS) and one-electron properties, such as relative binding tendency between the atom and the model cluster, and hybrid bonding tendency between the alloying element and the host atoms. By comparing the four models of Ti4Al14X cluster, the effect of the Fe, Ni or Cu atom on the physical properties of Al3Ti-based L12 intermetallic compounds is analyzed. The results indicate that the addition of the Fe, Ni or Cu atom intensifies the relative binding tendency between Ti atom and Ti4Al14X cluster. It was found that the Fermi level (EF) lies in a maximum in the DOS for Ti4Al14Al cluster; on the contrary, the EF comes near a minimum tn the DOS for Ti4Al14X (X=Fe, Ni and Cu) cluster. Thus the L12 crystal structure for binary Al3Ti alloy is unstable, and the addition of the Fe, Ni or Cu atom to Al3Ti is benefical to stabilize L12 crystal structure. The calculation also shows that the Fe, Ni or Cu atom strengthens the hybrid bonding tendency between the central atom and the host atoms for Ti4Al14X cluster and thereby may lead to the constriction of the lattice of Al3Ti-base intermetallic compounds.
基金Key Research and Development Program of Shandong Province,China (No. 2021ZLGX01)the National Natural Science Foundation of China (No. 52071190)the Shandong Provincial Natural Science Foundation,China (No. ZR2021YQ34)。
