Al_(0.3)CoCrFeNi纳米晶高熵合金在碱性溶液中的电化学性能

Electrochemical Properties of Nanocrystalline Al_(0.3)CoCrFeNi High-entropy Alloy in Alkaline Solution

通过高压扭转方法制备了平均晶粒尺寸为30nm的Al_(0.3)CoCrFeNi纳米晶高熵合金,利用电子背散射衍射仪、透射电镜、动电位极化曲线和交流阻抗谱测试等方法研究了其显微组织和在NaOH溶液中的电化学性能,并与铸态粗晶高熵合金进行了对比。结果表明:粗晶和纳米晶高熵合金的显微组织均为简单面心立方结构,但纳米晶高熵合金的位错密度较粗晶高熵合金的提高了近10个数量级;同时,相比于粗晶高熵合金,纳米晶高熵合金的自腐蚀电流密度降低了42.9%,维钝电流密度降低了21.6%,表现出优异的耐腐蚀性能,这主要归因于高压扭转过程引入的高密度晶界和位错;通过高压扭转使晶粒细化至纳米级是增强高熵合金耐碱腐蚀能力的一个有效途径。

The nanocrystalline Al0.3CoCrFeNi high-entropy alloy（HEA）with an average grain size of 30 nm was prepared by the high-pressure torsion（HPT）method.The microstructures and electrochemical properties in NaOH solution of the nanocrystalline HEA were investigated by electron backscatter diffraction,transmission electron microscope,potentiodynamic polarization curves and electrochemical impedance spectroscope and compared with those of the as-cast coarse-grained HEA.The results show that the microstructures of both coarse-grained and nanocrystalline HEAs exhibited a face-centered cubic structure,but the dislocation density of the nanocrystalline HEA was improved by 10 orders of magnitude than that of the coarse-grained HEA.Comparing to that of the coarse-grained HEA,the corrosion current density and passive current density of the nanocrystalline HEA were reduced by 42.9% and 21.6% respectively,showing the superior corrosion resistance,which was mainly ascribed to the high densities of grain boundaries and dislocations induced by HPT.Refining the grain size to nanoscale by HPT was an effective access to improving the alkali resistance of the high-entropy alloy.