Y对(TiCrNbAlY)C高熵碳化物薄膜摩擦学性能的影响OA

In order to investigate the effect of Y content on the microstructure,mechanical and tribological properties of the(TiCrNbAlY)C high-entropy carbide(HEC)films.A series of(TiCrNbAlY)C HEC films with different Y contents were deposited on Inconel 718 high-temperature alloys and silicon wafers by the multi-arc ion plating(MAIP)system.The microstructures,mechanical and tribological properties,as well as the wear track and wear scar after the friction and wear tests were systematically characterized by X-ray diffractometer(XRD),scanning electron microscope(SEM),transmission electron microscope(TEM),nanoindentation tester,and ambient tribometer.It was found that with the increase of Y content in the HEC films,the phase structure of the films did not change significantly at first,and the original FCC structure was maintained.With the increasing Y content,the structure of the film could not maintain the FCC structure and would gradually transfer to amorphous structure.This mainly resulted from that the atomic radius of Y element was significantly larger than that of several other metal elements in the(TiCrNbAlY)C films.When excess Y were added into the HEC films,more Y atoms occupying the cationic sublattice sites in the FCC structure led to excessive lattice distortion.Thus,the films with Y content of 7.8at.%presented the amorphous structure in the XRD pattern.In addition,the excess Y was also present in the metallic phase,which was harmful to the mechanical properties of films.Corresponding to the structural evolution of the films,both the hardness and elasticity modulus did not change significantly with the increasing of Y content at first.However,when the Y content increased from 3.5at.%to 11.3at.%,the hardness and indentation modulus of the films synchronously decreased from(21.06±0.47)GPa and(273.32±16.02)GPa at 3.5at.%to(15.81±0.65)GPa and(224.06±17.73)GPa at 11.3at.%,respectively.This was not only related to the amorphization of the films,but also to the formation of the soft metal Y phase due to the excess Y.As regard to the tribological properties of the films,it was found that even a small amount of Y doping(3.5at.%)could significantly improve the tribological properties,especially for the wear rate.Benefiting from the formation of a stable transfer layer on the surface of the counterpart ball when friction tests were conducted on the films doped with Y,the wear rate drastically decreased from 3.18×10-6 mm3/(N·m)of films free of Y to the 7.23×10-7 mm3/(N·m)for films with 7.8at.%Y.However,since excess Y content substantially reduced the mechanical properties of the films,the wear rate of the films increased slightly to 1.56×10-6 mm3/(N·m)when the Y content increased to 11.3at.%.In summary,an appropriate doping amount of Y can effectively improve the bonding force and wear resistance of the(TiCrNbAlY)C HEC films without reducing the mechanical properties.The results in this work will provide a certain reference for the further development and industrial application of high-entropy carbide films.