Fe元素含量对FeCrMnAlCu高熵合金在3.5%NaCl溶液中耐腐蚀性能的影响

The Influence of Fe Content on the Corrosion Resistance of FeCrMnAlCu High-Entropy Alloys in 3.5% NaCl Solution

摘要:

本文采用真空电弧熔炼技术制备了FexCrMnAlCu(x=0, 0.5, 1, 1.5, 2)高熵合金，使用XRD、SEM、EDS对腐蚀前后合金的相结构与微观组织进行了表征，通过动电位极化曲线、EIS、XPS以及浸泡实验对合金在3.5% NaCl溶液中的腐蚀行为与氧化膜成分进行了表征，研究结果表明：FexCrMnAlCu高熵合金均为BCC+FCC相的双相结构，Fe元素的添加使得BCC相衍射峰强度逐渐增强。随着Fe含量的增加，合金的耐腐蚀性能先增强后减弱，添加了Fe元素的合金耐腐蚀性能均强于不含Fe的合金，这是由于Fe元素的加入使得晶粒尺寸发生了变化，使得单位面积上的晶界数量改变，从而造成耐腐蚀性能的变化。FexCrMnAlCu合金的腐蚀类型主要为晶间腐蚀，腐蚀后合金表面形成了由各元素氧化物组成的氧化膜。Fe1.5CrMnAlCu合金的自腐蚀电流密度最小(1.75×10-6 A/cm2)、自腐蚀电位最正(-0.589 V)，容抗弧半径最大。

Abstract:

This study employs vacuum arc melting technology to fabricate FexCrMnAlCu (x=0, 0.5, 1, 1.5, 2) high-entropy alloys. The phase structure and microstructure of the alloys before and after corrosion were characterized using XRD, SEM, and EDS. The corrosion behavior and oxide film composition of the alloys in a 3.5% NaCl solution were investigated through potentiodynamic polarization curves, EIS, XPS, and immersion tests. The results indicate that FexCrMnAlCu high-entropy alloys exhibit a dual-phase structure of BCC+FCC. The addition of Fe enhances the intensity of the BCC phase diffraction peaks. As the Fe content increases, the alloy"s corrosion resistance initially improves and then deteriorates. Alloys with added Fe exhibit superior corrosion resistance compared to those without Fe. This is attributed to the change in grain size caused by the addition of Fe, which alters the number of grain boundaries per unit area, consequently affecting the corrosion resistance. The primary type of corrosion observed in FexCrMnAlCu alloys is intergranular corrosion. After corrosion, an oxide film composed of various elemental oxides forms on the alloy surface. The Fe1.5CrMnAlCu alloy exhibits the lowest self-corrosion current density (1.75×10-6 A/cm2), the most positive self-corrosion potential (-0.589 V), and the largest impedance arc radius.