Study On The Precipitation Of Soft Metal In TiN-Cu Coatings And Mechanisms Of Defect Self-healing

Prepare TiN-Cu coatings with different Cu content(58%,75%)on Si(100)by magnetron sputtering(MSP-300B).Study on the micro-structure,component,mechanical properties and self-healing properties by X-ray diffraction(XRD),Energy Dispersive Spectrometer(EDS),roughness meter,Scanning Electron Microscope(SEM)and nano-indentation.In addition,the migration phenomenon of soft metal from inside the coating and the self-healing mechanism were also investigated.From the research we can draw following conclusion:The TiN-Cu coating was composed of TiN(fcc)and Cu(fcc)under room temperature.And because of the high content of Cu,the grains in the cross-section were not columnar,the columnar crystal was interrupted.In addition,on the surface of the coating,the grains were clustered and the size was about 0.1?m~0.15?m.There existed some micro-holes between the grains boundary,the size of the holes was about 50 nm.From the EDS mapping,it can be seen that the elements were distributed evenly in the coatings,which indicated the coating prepared by magnetron sputtering was even.It can be found that the vacuum heat treatment didn‘t affect the phase composition of the TiN-Cu coating,and the coating was still composed of TiN(fcc)and Cu(fcc).However,compared with the TiN-Cu coating at room temperature,the diffraction peak of Cu at 300? and 600? heat treatment was stronger and higher with the increase of the heat treatment temperature.The stronger peak indicated that the surface Cu content increased with the raising temperature,and the crystallization became better.Further observed the surface morphology of TiN-Cu coating with different heat treatment temperature,it can be observed that with the increase of the heat treatment temperature,micro particles were observed on the coating surface,and the particles were evenly distributed on the surface.For high Cu content coating,when the heat treatment temperature was 300?,the particle size was 1~2?m,while when the temperature increased to 600?,the particle size increased and they tended to spread on the coating surface.Combined with the analysis of the EDS and XRD patterns,it can be deduced that the particles on the surface were Cu.Nanoindentation test was conducted on the samples for further research.The result showed that at room temperature,the hardness and elastic modulus of the coating kept constant with the increase of the depth,and they were 3.7 GPa and 125.0 GPa respectively,the Cu was distributed evenly along depth.While after heat treatment at 300?,the hardness and elastic modulus gradually increased with the increase of depth,and finally they would reach the value under room temperature,the Cu content decreased with the increase of the depth.Because the Cu could migrate from inside to the coating surface,it can be indicated that Cu inside the coating may have positive effect in healing the coating defects.The self-healing effect was related to three aspects: the Cu content in the coating,vacuum heat treatment temperature and the defects morphology.