Atom Packing Study Of The Σ5 Grain Boundary In TiAl Alloys By Simulations

y-TiAl alloy has excellent comprehensive properties,low density,high yield strength,high specific rigidity,good oxidation resistance and good creep resistance at high temperature.As an important structural materials used in high-temperature regime in the contemporary aerospace,weapons,civilian industry and other fields,γ-TiAl has a wide range of applications.But the alloy is brittle at room temperature,and has poor ductility.Therefore,its deformation processing is difficult To further meet the practical application needs of the TiAl alloy,it is necessary to investigate the structural changes as the temperature increases.Grain boundary structure has a significant effect on the properties of alloys.It is important to study the structural changes in grain boundaries with the temperature increase.In this paper,we perform the molecular dynamics simulations to study atom packing changes of a CSL5 grain boundary on heating within the framework of Embedded Atom Method(EAM).The heating processes include directly heating process and continuously heating processes,where the continuously heating processes have two heating rates of 6.25×1012K/s and 3.125×1012K/s.The grain boundary energy and atom packing changes are analyzed.The following results are obtained..The simulated system includes grain boundary region,the regions between the grain boundary and the bulk region,and the bulk regions.The atom packing structures in the grain boundary region and the matrix are affected by the temperature.At room temperature,most of the atoms in the grain boundary are located at lattice points.As the temperature increases,a considerable number of atoms can not be located at the coherent lattice points.In the grain boundary area there are vacancies,interstitial atoms,and other defects,while the regions being adjacent to the grain boundary area also have a variety of defects.In the directly increasing temperature,at the high temperatures,the atomic packing structures in the grain boundary region,transition region between the grain boundary-grain matrix,and the matrix region are changed significantly.When the temperature is very high,the grain boundary region appears disorderly packing of atoms.At different continuously heating rates,the temperature change mainly affects the atomic packing structures in the grain boundary region.