Microstructure and corrosion resistance of nanocrystalline Alx CrCoNi high-entropy alloy films
AlxCrCoNi(x=0.08,0.3 and 0.7)high-entropy alloy films with different Al contents were prepared by magnetron co-sputtering using high-purity Al target and CrCoNi target.Surface morphology,composition and internal microstructure of the films were characterized,and the mechanical properties and corrosion resistance of the films were analyzed using nanoindentation and electrochemical testing.The results show that the AlxCrCoNi films exhibit good uniformity and density,and with the increase of Al content,the microstructure of the films gradually transforms from nanocrystalline structure to dual-phase structure of nanocrystalline and amorphous.Under the same nanoindentation testing conditions,the Al-0.3 film has the highest hardness value.The electrochemical test results show that the corrosion current density of the Al-0.7 film is the lowest,and the total resistance of the fitting circuit is the highest,showing excellent corrosion resistance.Theoretical analysis shows that a certain volume fraction of amorphous can effectively improve the hardness of the film,and the presence of amorphous can effectively hinder the diffusion of corrosive ions,thus significantly improving the corrosion resistance of the film.
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