Effects of Vacancy Concentration on Damping Property of γ-TiAl Coating
In order to study the effect of vacancy defects on the damping performance of γ-TiAl coating,molecular dynamics(MD)was used to simulate the reciprocating vibration of γ-TiAl coating with different vacancy concentrations.The changes of stress-strain,stored potential energy,dislocation line density,defect area,and microstructure were compared and analyzed.The results show that with the increase in vacancy concentration,the energy consumption of γ-TiAl coating increases gradually,and the damping performance is enhanced obviously.The stored potential energy of γ-TiAl coating with different vacancy concentrations changes periodically,and the range of variation decreases gradually with the increase in vacancy concentration.In the process of vibration simulation,vacancy defects will evolve into dislocation lines and other defects,resulting in increased dislocation density and defect area.The movement,evolution and annihilation of different defects are the main sources of energy consumption of γ-TiAl coating.In addition,γ-TiAl coating with high vacancy concentrations produces more plastic deformation,neck shrinkage and more holes,which further increases the energy dissipation.
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