Construction Of Interatomic Potentials For Binary Alloys Of Transition Metals And Its Application

The development of quantum mechanics,calculation algorithm and computer capability make a distinct progress in the Computation Physics and Computational Materials. Despite of the great success on the first principle calculational method based on density function theory and its broad applications, it is still difficult to calculate the complicated characteristic of system with thousands upon thousands atoms by ab initio method based on the actual calculational condition and theoretics. Therefore the effective interatomic potentials are widely used and playing an important role in the investigation of the statics, dynamics and statistical mechanics for various materials.For binary metallic alloy system, n-body potential scheme is widely employed, which is usually constructed by fitting the physical properties of various intermetallic compounds in the alloys system. However, when turned to alloys system that features positive heat of formation and has no intermetallic compounds or that although characterizes negative heat of formation yet exists little formation, no enough physical properties necessary in fitting the n-body potential are available, and consequently no means to construct a realistic interatomic potential.The development of the interatomic potentials and the leading of Numerical Method were introduced. The interatomic potentials model for pure metals and alloys and its method which can be fitted were mainly presented. The Finnis-Sincalir n-body potential for binary alloys which were composed of transition metals can be fitted by cohesive energy and the lattice parameters, Rose of P-V relationship, the Least Square Method and overdetermined equations under the condition of no-equilibrium states. The cohesive energy and the lattice parameters can be acquired by first-principles.Following this idea, four binary alloys systems, i.e. Fe-Al, Fe-Cr, Cr-Ni and Fe-V, were chosen to fit their respective Finnis-Sincalir n-body potential.The derived potentials were proved to be able to reproduce those important physical properties and the reproduced data matched well with those obtained by first-principles calculations or from experiments. Morever, based on the constructed potentials, the alloys of bulk modulus of Fe-Al,Fe-Cr,Cr-Ni,Fe-V, and their first derivation for pressure were calculated .The calculation results of bulk modulus were agreed with the theoretics: which were increased as the pressure increasing. The first derivations of bulk modulus were reduced as the pressure increasing in case of compression ratio is large. Lend support to the feasibility of the potential construction approach.