Effect Of TiN On The Properties Of AlCoCrFeNi High Entropy Alloys And Coatings

High-entropy alloy?HEA?is a kind of multi-principle alloy,which can obtain excellent properties such as higher hardness,good wear resistance and corrosion resistance by designing the principal elements of high-entropy alloys and adjusting the content of elements.Due to its good comprehensive properties,the development prospect of HEA is relatively broad,and it gradually attractes lots of attention in the field of materials in recent years.In this paper,AlCoCrFeNiTiN_x?x=0.0,0.2,0.4,0.6,0.8,1.0?HEA coatings were prepared by a combination of plasma spraying and laser remelting technologies.At the same time,Al_0.5Cr_0.9FeNi_2.5?TiN?_x?x=0.0,0.2,0.4,0.6,0.8,1.0?and AlCoCrFe Ni?TiN?_x?x=0.0,0.2,0.4,0.6,0.8,1.0?HEA were prepared using a vacuum arc melting equipment.The alloy materials were compared to study the effect of different TiN content on the microstructure and properties of AlCoCrFeNi?TiN?_x HEA coating.Phase composition and microstructure morphology of the coatings and alloy were investigated by XRD,SEM equiped with EDS,and the microhardness,friction,wear and compression were tested.The results indicate that the addition of TiN can promote the BCC phase formation in FCC-dominant Al_0.5Cr_0.9FeNi_2.5 HEA and BCC-dominant AlCoCrFeNi HEA.Ti N has a dispersive strengthening effect on the alloy,In addition,there is solution strengthening effect in smelting process,which is because Ti and other elements are easy to form solid solution after decomposition of TiN.In contrast,the phenomenon of TiN dissolution and precipitation occurs in the AlCr FeNi?TiN?_x HEA coatings after laser remelting,and the precipitated phase appears is Ti-Al-N phase.Therefore,the coating of AlCoCrFeNi?TiN?_x HEA after laser remelting is strengthened by dispersion strengthening and precipitation strengthening.With the addition of TiN,the microhardness values of Al_0.5Cr_0.9FeNi_2.5 HEA,AlCoCrFeNi HEA,and laser remelted AlCrFeNi?TiN?_x HEA coatings have been increased.When x=1,the peak values of microhardness in each HEAs system are 657.7HV,635HV,and 659.1HV respectively.Among them,Al_0.5Cr_0.9FeNi_2.5 HEA is obvious affected by TiN,and the peak value of its microhardness is 3 times that of the HEA without TiN added.With the addition of TiN,the wear resistance and microhardness of alloys with different compositions showed a consistent trend.In the friction and wear test,with the increase of TiN content,the wear debris decreased gradually and the furrow became shallow,which indicated that the wear resistance was improved significantly.At the same time,the reason why the wear machine changes from adhesive wear to abrasive wear.Among them,the coefficient of friction of the AlCoCrFeNi?TiN?_x HEA coating after remelting,at x=1.0,obtains a minimum value between 0.28 and 0.29.When x=0.8,the friction coefficient of Al_0.5Cr_0.9FeNi_2.5?TiN?_x HEA reaches the minimum value?about 0.45?.The addition of TiN can improve the strength and plasticity of Al_0.5Cr_0.9FeNi_2.5 HEA and AlCoCrFeNi HEA in a certain range.Its optimal fracture strengths were 2006MPa?x=0.8?and1864MPa?x=0.6?respectively.