The Design And Properties Of Refractory Multiple-basis-element Alloy Films

Multiple-basis-element(MBE)alloys have potential application prospects in heat-resistant hard coatings and solar-thermal conversion coating due to its high strength and excellent phase stability.However,the studies on the thermal stability and mechanical properties of MBE alloy films are few,and the prediction of their phase structure is not perfect,which greatly limits the application and development of MBE films.On the other hand,the traditional way to develop MBE alloy films was lack of efficiency due to the complex components of MBE alloy.To solve these problems,the structural transformation of magnetron sputtered MBE alloys and their nitrides films with temperature and elemental changes was studied by means of composition adjustment and high-throughput fabrication.The mechanical properties,solar-thermal conversion efficiency and heat resistance were mainly focused.The mean issues include:The new parameter ?T was proposed to predict the phase formation of the MBE films.The parameter was applied to the composition design of NbZrTiSiAlNx,NbZrFeCoNiNx and(Ta0.5W0.5)100-x(Cr0.33Fe0.33V0.33)x MBE films,which verified its reliability.NbZrTiSiAlNx MBE films have good phase stability at 600 ? and can remain amorphous phase for a long time without crystallization.The NbZrTiSiAl MBE alloy films still have good amorphous structure at 900 ?.The nitride films of the alloys were nanocrystallized and precipitated with face-centered cubic structure.In addition,the hardness and modulus of elasticity of the films decreased after annealing at 700 ? for 24 hours.The thermal stability of NbZrTiSiAl MBE films can be reduced by adding nitrogen.Excess nitrogen can reduce the hardness of NbZrTiSiAl MBE films,but a small amount of nitrogen can strengthen the films.With the increase of deposition temperature,a small amount of nanocrystallization occurs in NbZrTiSiAl films.The hardness of NbZrTiSiAl films increases with the increase of deposition temperature.For NbZrFeCoNiNx MBE films,the increase of nitrogen content will reduce the mechanical properties of the films.NbZrFeCoNiNx MBE films are typical amorphous films in deposited state.When RN increases to 33.3%,the phase structure remains amor:phous.The hardness and modulus decrease with the increase of nitrogen content at room temperature.With the increasing content of Ta and W,the phase structure of(Ta0.5W0.5)100-x(Cr0.33Fe0.33V0.33)x MBE alloy films transforms from amorphous structure to BCC structure when x=24.The roughness of Ta42W40Cr6Fe6V6 thin films reaches the maximum of 61.95 nm in the range of measured composition.The visible and near infrared reflectance of Ta42W40Cr6Fe6V6 thin films are greatly reduced due to the optical trap effect.The solar absorption of Ta42W40Cr6Fe6V6 thin films reaches the maximum of 80.91%among the(Ta0.5W0.5)100-xCr0.33Fe0.33V0.33)x films.The hardness of(Ta0.5W0.5)100-x(Cr0.33Fe0.33V0.33)x films increased with the formation of BCC phase.At the composition point of Ta42W40Cr6Fe6V6 the hardness of the films can reach 11.5 GPa,which is the highest hardness within the range of tested components.After annealing for 0.5 h at 600 C,the nucleation and growth of the BCC phase grains occurred at x=43,and the hardness of the films increased greatly.The maximum hardness of the films after annealing could reach 20.96 GPa.The increase of BCC phase in(Ta0.5W0.5)100-x(Cr0.33Fe0.33V0.33)x MBE films will lead to the increase of corrosion tendency of the films,but the corrosion rate has not changed significantly.At x=43,the corrosion resistance of the film decreased obviously.The contact angle of Ta38W38Cr8Fe8V8 can reach 104° and its hydrophobicity is the best.The contact angle of Ta45W42Cr4Fe5V4 is only 61°,and its hydrophilicity is the best.In the amorphous phase region with x=82?33,the surface energy of the films with high mixing entropy is the highest,which is 34.4 mJ.m-2.After BCC phase precipitated in the film,the surface energy increased gradually.The surface energy of Ta45W42Cr4Fe5V4 thin films with complete BCC phase structure is the largest in the range of measured composition,which is 46.1 mJ.m-2.