Research On Structure And Properties Of Zr-Ta-Nb-Ti-W-N Multi-element Films

In order to improve the wear resistance of Ti6Al4V alloy, multi-target magnetronsputtering and nitrogen plasma based ion implantation are used to preparedquaternary TaNbTiW alloy films,（TaNbTiW）N nitride films, quinary ZrTaNbTiWalloy films and （ZrTaNbTiW）N nitride films. The chemical composition, chemicalbonds, constituent phase, microstructure are investigated using X-ray fluorescencespectroscopy （XRF）, X-ray photoelectron spectroscopy （XPS）, XRD, SEM andTEM techniques. Wear properties and its mechanism of the films are analyzed.Quaternary TaNbTiW alloy films are deposited on Ti6Al4V alloy by magnetronsputtering. Structure and performance of the films are investigated. XRD shows thatthe films have body-centered cubic （BCC） structure, and the diffraction peaks areshift to higher angle with the decreasing of Ta, Nb content and increasing of Ti, Wcontent. The films that annealed at500,700,900℃have good phase stability andoxidation resistance, and the oxidation resistance is enhanced with the increasing ofTi, W content. The field emission scanning electron microscope （FESEM）observation shows that the top surface of the films is granular-like structure, and thecross-section is columnar structure. The maximum hardness of the film deposited onTi6Al4V is5.2GPa; it is increased about13%compared to Ti6Al4V substrate. Thefriction coefficient of the films is higher than Ti6Al4V alloy, but the wear rate isdecreased17%.（TaNbTiW）N films are prepared by combining of magnetron sputtering depositionand nitrogen plasma based ion implantation （N-PBII）. XPS investigations indicatesthat the nitride films are like composed of Ta-N, Nb-N, TiNxOy, TaOx, Ta and W.XRD shows that the nitride films are composed of BCC and FCC solid solutionstructures. The hardness and modulus of the nitride films are increased withincreasing implantation time and the hardness and modulus of alloy filmTa_25.4Nb_13.4Ti_20.9W_40.3implanted3h reaches maximum values of9.0and154.1GPaafter nitrogen implantation. The friction coefficient and the wear rate of（TaNbTiW）N films are significantly decreased compared to TaNbTiW alloy filmsand substrate Ti6Al4V. The1h nitrogen implantation film has minimal wear rate. Ascompared to alloy film and substrate, it is decreased200%and223%, respectively.The wear mechanism of the nitride film is abrasive wear, accompanied by adhesivewear.Quinary ZrTaNbTiW alloy films are prepared by multi-targets magnetronsputtering. XRD shows that the alloy films ZrTaNbTiW are simple BCC structure or amorphous. When the atomic percent of Zr exceeded35%, the films are exhibitedamorphous phase. The films that annealed at500,700,900℃have good phasestability and oxidation resistance, and the oxidation resistance is enhanced with theincreasing of Ti, W content. FESEM analysis results show that the top surface of thefilms is granular-like structure, and the cross-section is columnar structure. Thesurface particles gradually become small and columnar crystal gradually becomesdense with the increasing of Zr content. The maximum hardness of the filmdeposited on Ti6Al4V alloy is6.7GPa. The friction coefficient of the films is about0.35, higher than Ti6Al4V alloy. But the wear rate is significantly lower thanTi6Al4V alloy; it is decreased more than2times. The wear mechanism is mainlyabrasive wear and adhesive wear, accompanied by oxidative wear.Multi-element （ZrTaNbTiW）N films are prepared by multi-target magnetronsputtering deposition and nitrogen plasma based ion implantation （PBII）. It is seenthat a mixture of ZrN, TaN, TiN, Nb-N, ZrO₂, Ta, Nb and W is formed. Afternitrogen implantation, the alloy films （ZrTaNbTiW）N are composed of BCC andFCC solid solution and the width of columnar grain is about5nm. The hardness andmodulus of the films are improved significantly after nitrogen ion implantation andreach maximum values of13.5and178.9GPa, respectively. The （ZrTaNbTiW）Nfilms have better wear resistance than its ZrTaNbTiW alloy films and Ti6Al4Vsubstrate, the wear rate is decreased3.6times and5times, respectively.Through studying on the nitrogen implantation in TaNbTiW films, Zr additionin TaNbTiW films, and Zr addition then nitrogen in TaNbTiW films, respectively. Itis found that FCC nitrides are formed in the TaNbTiW films after nitrogenimplantation. The structure of the films is changed to FCC and BCC solid solution.After Zr addition in TaNbTiW films, the lattice distortion is increased. When thecontent of the each element Zr, Ta, Nb, Ti and W are in the range of the high entropyfilms, the films have high mixing entropy. So the lattice distortion and high mixingentropy lead to the formation of amorphous phase. When the TaNbTiW films addedZr then nitrogen implanted, not only BCC nitrides formation but also significantlyincreases the mixing entropy of the films. The structure of the films is BCC andFCC solid solution. The TaNbTiW films have high hardness and wear resistance,and with the Zr addition, nitrogen implantation, Zr addition then nitrogenimplantation, the hardness and wear resistance presents successively increasingtrend.