Characterization Of Al-Cu-Fe Films Prepared By Three-target Magnetron Cosputtering

The Al-Cu-Fe film has attracted more and more attention about its application ofproperties such as wear resistance, anti-friction, non adhesive, heat resistance, corrosionresistance, because it possess good properties, easy achieved and low cost. Althoughmore studies on the fabricated methods, microstructure and properties of Al-Cu-Fe filmwere reported, the relationships between the surface morphology, nucleation and growth,control of composition, microstructure, interface characteristics and the properties for theAl-Cu-Fe film by three-targets cosputtering are needed more research, in order toaccelerate its practical application in industry.In the condition of the different cosputtering parameters （such as sputter power,sputter pressure, substrate temperature, sputter bias, sputter time） and anneal parameters,the Al-Cu-Fe films were prepared by three-targets magnetic cosputtering. The surfacemorphology, nucleation and growth, composition control, atomic uniting state,microstructure, interface characteristics and phase transformation were studied by meansof AFM, EDS, XPS, TEM and XRD. Nano-indentation and nano-scratch meter wereused to investigate the influence of film preparation parameters on the nano-hardness andmodulus of film. The bond strength and tribological property between the film anddifferent substrates were discussed. The main conclusions are summarized as follows:Firstly, the surface roughness exponent of Al-Cu-Fe film is increased with theincrease of the sputter power and prolongation of sputter time. The surface roughness ofAl-Cu-Fe film is increased firstly and then induced, the size of island particles changessmaller. As the sputter pressure declines from2.0Pa to1.0Pa, the growth exponent ofAl-Cu-Fe film, β, drops from0.38±0.08to0.31±0.10. The surface roughness of film is obviously increased with the increase of substrate temperature. The size of islandparticles changes bigger. These results demonstrate that the film growth mechanism isdominated by the mode of vapor-coagulating diffusion. The surface roughness exponentand surface roughness of Al-Cu-Fe film is greatly decreased because of the reduction ofsputter bias. The surface roughness exponent of Al-Cu-Fe film on the stainless steel ishigher than that on the silicon. Furthermore, the greater the substrate surface roughness is,the smaller the surface roughness of Al-Cu-Fe film is.Secondly, the related Al content of film is raised as the substrate temperature rise up,and the related Cu and Fe content of film is decreased to some extent. The enhancementof sputter bias results in the increase of the related Al content of film. The composition ofAl-Cu-Fe film is influenced greatly. The increase or decrease of sputter pressure will notincrease or decrease linearly the relative content of film. Under the non-sputter bias, theoxides such asAl₂O₃, CuO and Fe₂O₃are formed on the film surface by the reason of theincrease of substrate temperature. However, Al₂O₃is just formed on the film surfaceunder the sputter bias and at room temperature. All composition around the interfacebetween the films and substrates is well-distributed and transition state.Thirdly, the Al-Cu-Fe film as deposited has generally amorphous microstructure.When the substrate temperature rises up to450℃, the crystalline microstructure is partlyformed in the film. While the substrate temperature increase to550℃, many phases suchas θ-Al₂Cu（Fe）, ω-Al₇Cu₂Fe, β-AlCu（Fe） and I-Al₆Cu₂Fe are evidently formed in thefilm according to the sputter power and time. The increase of sputter bias results to thegreat change of film microstructure at room temperature, and the film microstructurechanges from the amorphous structure to the amorphous plus microcrystallinecommixture structure. The transformation of Al-Cu-Fe film as deposited is depended bythe anneal temperature and anneal time, and the film microstructure changes from theamorphous structure to the quasicrystalline or crystalline structure.Finally, the increase of sputter power gives rise to the great increase in thenano-hardness of film. The major reason is that the activity of bond between the atoms in the film increases with the increase of sputter power. The enhancement of sputter biasresults in the increase of the nano-hardness and modulus of film. This results concernwith the fact, which the sputter bias improves the film density and increases the bondstrength between the film and substrate. Along with the prolongation of sputter time andthe increase of substrate temperature, the nano-hardness and modulus of Al-Cu-Fe film isslightly raised. The great improvement of nano-hardness and modulus of film afterannealing at550℃for60min is related with the dispersed strengthening that is producedby the formation of little quasicrystalline or crystalline phase. The bond strength andfriction coefficient between the film and substrate is increased with an increase ofsubstrate temperature and sputter pressure. The friction coefficient of film on the purealuminium substrate is minimum value while that on the pure copper substrate maximum.The bond strength of interface between the film and the1Cr18Ni9Ti stainless steelsubstrate is the greatest value; however that between the film and the pure coppersubstrate is least.