Ion Beam Polishing Processing And Mechanism Of TC4 Titanium Alloy

Due to the advantages of processing complex shaped surface,high machining precision and little effect on the base materials,Ion beam polishing technique,widely applied on the processing of semi-conduct materials and optical devices.However few researches focus on the possibility of ion beam polishing processing on metal materials.To take advantage of ion beam polishing technique abilities,investigation of the processing parameter suitable for implanted cardiovascular devices made by titanium alloy and research on the polishing mechanism have research and application value.In this research,a ion beam polishing device had been made for the investigation of Ar+ ion beam polishing parameters suitable for annealed TC4 titanium alloy preprocessed by mechanical grinding,with a origin surface roughness between 0.1 to 0.3 ?m.The possible effects on the microstructure,phase and ingredient of base material made by ion beam polishing process was studied.The surface binding energies of Ti,Al and V atom and the ZBL potential energy that descript the interaction of Ti and Ar atom were calculated based on the first principal calculation and density function theory,To deeply analysis the polishing mechanism,surface models with different orientation and morphologies was built and the evolution of surface models under ion beam bombardment was studied by molecular dynamic simulation.The results indicates that with proper parameters of ion energy,ion flux,and incidence angle,surface roughness Ra can drop to a minimum of 60 ?m after the bombardment of Ar+ ion flux.The analysis of the post-processed base materials shows that ion beam polishing process has little effect on the microstructure,phase and macro component distribution,while the X-ray photoelectron spectroscopy examination indicates that the atom percentage of Ti was dropped after the process.The molecular dynamic simulation shows that atom sputtering and surface atom displacement occurred under the ion beam bombardment process,the evolution of surface morphology made by the interaction of atom sputtering and atom displacement.The sputtering yield of atom,the average displacement of atoms and the degree of post-processed lattice distortion varied with different orientation and surface morphology,a higher average atom displacement and lattice distortion occurred with the dense crystal orientation and high roughness surface model while a smooth surface under ion bombardment sputtered more atoms than rough surface.