The Preparation And Microstructure Of Ti₂AlN(Max Phase) Thin Films

As a new type of three component compound,Ti₂AlN has the properties of low density,high modulus,good conductivity,high temperature oxidation resistance and low friction coefficient.This series of excellent properties make it have wide application prospect and become the research focus.The purpose of study was to optimize the preparation process of Ti₂AlN thin films,and researched the influence of process parameters,annealing temperature and substrate materials on the microstructure of the films.In this paper,Ti-Al-N thin films were prepared by magnetron sputtering ion plating,and the films were annealed in vacuum.The phase composition and micro-structure of Ti₂AlN films were examined by X-ray diffraction,Scanning electron microscopy,Atomic force microscope,Transmission electron microscopy.The hardness and elastic modulus of Ti₂AlN films were measured by nano-indentation.The tribological properties were measured by the friction and wear-tests.The oxidation resistance was analyzed by oxidation experiments.The Ti-Al-N thin films prepared by Ti and Al metal targets were mainly TiN phase,and the Ti₂AlN phase was not detected after vacuum annealing.With the improvement of the process,Ti-Al-N thin films prepared by the Ti-Al(Ti:Al=2:1)compound targets mainly exist amorphous,and the Ti2AIN phase was detected by vacuum annealing.The process of Ti-Al compound targets and the biaxial rotation of workpiece frame made the films more uniform,and the Ti₂AlN films was successfully prepared after vacuum annealing.With the increase of annealing temperature,the crystallinity of the films becomes larger,and it will produced other phase when the temperature was too high.In addition to the Si substrate,the films prepared on the single crystal MgO and poly crystal line Al2O3 substrates were successfully detected Ti₂AlN phase after vacuum annealing.The results show that the substrates has little effect on the microstructure of the films.At 700?vacuum annealing the films had a high degree of crystallization and no impurity phase.The hardness was about 25.3GPa and the elastic modulus was about 315.2GPa.The wear mode of the annealed films were electric die grinder.The surface morphology of the films is relatively smooth,and the Al2O3 was attached to the surface,which prevented the further reaction of oxygen and made the film had good oxidation resistance.