The Effect of a Light Impurity on the Electronic Structure of Dislocations in NiAl

The effect of light impurities (C, N) upon the electronic structure of the [100](010) edge dislocation core in NiAl single crystals is investigated by using the Dmol and the discrete variational method within the framework of density functional theory. The impurity segregation energy, interatomic energy and charge distribution are calculated, and the effects of impurity atoms upon the dislocation motion are discussed. The energy analysis shows that both C and N atoms can stabilize the [100](010) edge dislocation core, and prefer to occupy the interstitial site in the Center-Ni dislocation core. Meanwhile, the impurity atoms can form strong bonding states with their neighboring host atoms via hybridization between the 2p orbitals of the impurity atom and the 3d4s4p orbitals of the host Ni atoms; as well as between the 2p orbitals of the impurity atom and the 3s3p orbitals of the host Al atoms. The strong interaction between impurity atom and host atoms in the dislocation core may improve the strength of NiAl single crystals.

Weakening Hydrogen Bond of Thick Oil of Petroleum by Several Catalysts

The process of use catalyst or functional material that contains iron ion to weaken -O-H-X- (X=O, N and S) bond of the thick oil to reduce viscidity or crack, in aspects of the ion charge, covalent bond order, total energy and the average distance of Fe-X, is studied with density function theory and discrete variational method (DFT-DVM), one of the first principle methods. Sulfur is with positive charge, and the hydrogen bond of -O-H-S- does not form. The strength of -O-H-N- hydrogen bond is a bit larger than that of -O-H-O-. With the decrease of the distance of Fe-X (X=O, N), the charge of Fe ion increases, the charge of hydrogen ion decreases, and hydrogen bond is weakened.

Chemical Bond and Property of TiB2/Cu Composite and Doped Series

The related single phases, composites of TiB2/Cu and doped with Fe or Mo series were calculated by the density function and discrete variational method (DFT-DVM) to study the relation among electronic structure, chemical bond and properties. When Fe or Mo is doped into composite, the ionic and covalent bond become stronger, and the interaction between Cu and TiB2 phases also becomes stronger. The influence of doping Mo is more obvious than that of doping Fe. The results are consistent with the experiment that additives of Mo and Fe can improve preparation of TiB2/Cu composite, and effect of additive of Mo is more obvious than that of Fe.