The Construction And Application Of Nb And β-stype Ti-25%Nb Alloys Interatomic Potentials

In recent years, the β-stype in Ti-Nb alloys has received considerable attentionwith its low elastic modulus,high strength and excellent shape memory effect aroundthe world.This alloy is used for a variety of industries,such as cell phone antenna,coffee maker, vacuum flask;and also for its corrosion resistance and brilliantbiocompatibility,making use wide substantial increase in clinical medicine. In order tounderstand the unique properties of Ti-Nb alloy,the micro-level is an effective methodto study the deformation mechanism.On this micro-level,molecular dynamics simulation is one of the main theoreticaltools to research the material properties,and based on interatomic potential betweenthe atoms of the material.This article describes models of the interatomic potentialand its range of application, are divided into the pair potential and the many-bodypotential.Pair potential include Lennard-Jones potential,Morse potential andBorn-Mayer potential; The many-body potential include Effective Medium BasedMethod, Embedded Atom Method, F-S potential and longe-range F-S potential.We build the FCC structure of Ti, BCC structure of Nb, β-stype in Ti-25%Nballoy with EAM potential format. Firstly, we fit their pair potentials, according to thewave function data,we fit the electron density of Ti, Nb and the β-stype in Ti-25%Nballoy, and then fit the embedded potential curve, obtain the interatomic potential ofmetals and alloy.In order to investigate the stability of their structures, we compare their cohesiveenergy curve with Rose curve, then discover the curve after truncation processingcoincide with Rose curve substantially, the results of using the built potential tocalculate the elastic constants and elastic modulus, the average shear modulus and thecohesive energy, are also satisfactory. In the constant volume conditions，wecalculate cohesive energy of the three structures, the results show that the BCCstructure of the β-stype in Ti-25%Nb alloy’s cohesive energy is stronger than theFCC and HCP structure’s, so consistent with the facts. Finally, calculation of Ti, Nb and the β-stype in Ti-25%Nb alloy single vacancy formation energy is in acceptablerange,compared with input values.