Molecular Dynamics Simulations Of Mo And Ni₃Al Nanowires Under Uniaxial Tensile Strain

At present, nanomaterials are one of the hottest research points in international materials science. Nanotechnology is considered to be the most promising research area in the 21st century, which is widely used in ceramics, optoelectronics, microelectronics, biotechnology and so on. As a typical one-dimension nanomaterials, nanowires (NWs) which contain a lot of surface atoms and own large surface area to volume ratio is particularly active. The mechanical properties of NWs are the common concerns. Therefore, this article on the mechanical properties of NWs has important practical significance. In present paper, modified analysis embedded-atom method (EAM) is used to describe the interactions between atoms. Using molecular dynamics simulation, we studied the tensile behaviors of Mo and Ni3Al NWs under uniaxial tensile strain. It's analyzed that the mechanism of phase transitions and mechanical properties under uniaxial tension. The effects of temperature and size on the mechanical properties of NWs are also discussed.The phase transition processes of a single crystal Mo NWs under uniaxial tensile strains were studied at 50K with molecular dynamics simulation. Two phase transitions have been observed during the uniaxial tensile processes. The first one is the configuration of Mo NWs transformed from body-centered cubic (bcc) structure to face-centered cubic (fee) structure and the second one is that transformed from fee structure to bcc structure. The phase structures have also been demonstrated with radial distribution function (RDF) analyses. Two average atom energy curves of bcc structure and fee structure as the function of the double layer space along [001] direction were obtained with the help of embedded-atom method potential calculations, by which the strain-driven bcc-to-fcc and fcc-to-bcc phase transition mechanisms have been clarified clearly for Mo NWs under uniaxial tensile strain. In high temperature, the phase transition processes became more complicated and much more hexagonal close-packed (hcp) structure and fcc structure were found. It's obvious that hcp and fcc structures are good at high temperature and high pull. At the aspect of mechanical properties, the young's modulus and yield strengths are decreased with increasing temperature in the tensile processes of Mo and Ni3Al NWs. The young's modulus and yield strengths are increased with increasing NWs size in the tensile processes of Ni3Al NWs. The mechanical properties of the Ni3Al NWs with Re are different from ones of the Ni3Al NWs. The location of Re in NWs has the obvious effect on the mechanical properties of Ni3Al NWs. According to our study, the difference of mechanical properties is caused by the difference of the bonding strength in Re atom and other atoms around Re atom.