Development And Application Of EAM Empirical Potential For Pt-Rh Alloys

Pt-Rh alloy is an excellent material.Due to its excellent high-temperature performance and catalytic performance,it has been highly valued in recent years in the aerospace,catalytic industry,glass industry and other fields.In order to gain a deeper understanding of the properties of Pt-Rh alloy,computational simulation from the atomic scale is a useful research method.The molecular dynamics method is an effective method to understand the properties of materials from the microscopic scale.It is based on Newton's second equation of motion.By integrating the Newton's second equation of motion,the position and velocity of the particles are obtained,and various properties of the material are calculated.Now molecular dynamics has been widely used in material simulation.Interatomic interaction potential is a necessary condition for classical molecular dynamics simulation.The accuracy of the potential function directly affects the description of the interaction force between atoms.However,due to the lack of suitable potential functions,a large number of metals or alloys cannot be studied using molecular dynamics simulations.The development of accurate and reliable potential functions has always been an essential subject of material calculation and simulation.The embedded atom method(EAM)potential is widely used to describe the interaction between atoms in metals.Compared with the traditional counterpart potential,the EAM potential introduces the contribution of electron density to the embedded energy,which can better describe the metal system.Obtained results similar to the experiment.In this paper,the EAM potential function suitable for the Pt-Rh alloy system is developed.In this paper,the first-principles calculation is used to obtain the data needed to fit the potential function.The force matching method is used to establish the empirical multi-body potential of the Pt-Rh alloy system under the theoretical framework of the embedded atom method(EAM).The EAM potential obtained by the application calculates the lattice constants,melting points,and elastic constants of Pt and Rh.It compares them with the first-principles calculation values or experimental data.The results show that the predicted values calculated using the EAM potential are in agreement with the experimental values or the first-principles calculation values,which can meet the requirements of molecular dynamics simulation of Pt-Rh alloy system.As an application of EAM potential in Pt-Rh alloy system,the uniaxial tensile deformation process of Pt₃Rh and Pt Rh₃ nanowires was simulated by using the constructed EAM potential function to explore the influence of strain rate,size and temperature on the deformation process of Pt₃Rh and Pt Rh₃ nanowires.The simulation results show that the mechanical properties of Pt₃Rh nanowires and Pt Rh₃ nanowires are related to the strain rate.Within the strain rate range of 1×10⁸ s^-1-1×10¹⁰ s^-1,the yield strength of the nanowires increases with the increase of the strain rate.This is because the high strain rate induces a disordered transformation of the crystal,which hinders the movement of dislocations;in exploring the effect of size on the uniaxial tensile mechanical properties of nanowires,small-sized Pt₃Rh nanowires and Pt Rh₃nanowires have a higher yield strength,which is related to the small surface nanowires having a higher ratio of surface atoms.During the stretching process,the small size nanowires require a more enormous external load to overcome the surface stress;In the study of the influence of axial tensile mechanical properties,it can be found that as the temperature increases from 10 K to 1000 K,the yield strength of Pt₃Rh nanowires decreases by 60%,while the yield strength of Pt Rh₃ nanowires decreases by 43%,at higher temperatures.The thermal motion of the atoms is more intense,the vibration generated at the equilibrium position is more significant,and it is easier to escape from the equilibrium position and participate in the slip of dislocations under the action of an external load,resulting in a decrease in the yield strength of the nanowire.