纳米晶Al_(x)CrCoNi高熵合金薄膜的组织结构及耐腐蚀性能

Microstructure and corrosion resistance of nanocrystalline Al_(x)CrCoNi high-entropy alloy films

选用高纯Al靶和CrCoNi靶,采用磁控溅射共沉积的方法制备了不同Al含量的Al_(x)CrCoNi(x=0.08、0.3和0.7)高熵合金薄膜。对薄膜的表面形貌、成分及内部微观结构进行了表征,并采用纳米压痕及电化学测试分析了薄膜的力学性能和腐蚀性能。结果表明:Al_(x)CrCoNi薄膜均表现出较好的均匀性和致密性,且随着Al含量的增加,薄膜的微观结构由纳米晶结构逐渐转变成纳米晶和非晶混合的双相结构;在相同的纳米压痕测试条件下,Al-0.3薄膜的硬度值最高。电化学测试结果表明,Al-0.7薄膜的腐蚀电流密度最低,拟合电路的总电阻最高,表现出较为优异的耐腐蚀性能。理论分析可知,一定体积分数的非晶可以有效提高薄膜的硬度,且非晶的存在可以有效阻碍腐蚀离子的扩散,因此显著改善薄膜的耐腐蚀性能。

Al_(x)CrCoNi(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 Al_(x)CrCoNi 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.