高熵合金Al0.3CrMnFe1.5Ni_x應用在硫酸溶液中之腐蝕特性質研究

Corrosion Property Studies of High Entropy Alloy Al0.3CrMnFe1.5Nix in Sulfuric Acids

高熵合金Al0.3CrMnFe1.5Nix於先前之研究中顯示，具有絕佳之強度、硬度、極高溫時效硬化能力，且在高溫環境中不易發生潛變的現象，因此在機械性質上已被廣泛研究，然而在腐蝕性質方面之研究至今仍所知有限。本成分之高熵合金於硫酸性環境中，合金中之Al易與溶液作用造成腐蝕破壞，使試片表面因而產生十分嚴重的局部腐蝕；然而合金中之Ni則有助於表面鈍態膜之形成。對於Al0.3CrMnFe1.5Nix高熵合金抗蝕能力之欠佳，藉由將合金成分中Ni含量提高至1份，會有助於表面鈍態膜之完整及其保護能力，因而可有效的提升於硫酸溶液中的抗蝕能力。由電化學阻抗頻譜分析，此結果應為試片表面Ni的氧化物或鈍態膜之強化作用，經由微觀結構分析及觀察也能明顯見到其抗蝕能力的提升。

In earlier research, high entropy alloy Al0.3CrMnFe1.5Nix has shown excellent mechanical strength, hardness, and harden-ability at high temperatures, and it does not creep easily in high temperature environments either. Although their mechanical properties have been extensively studied, their corrosion properties still remain mostly unknown at present. When exposed to an acid solution, the aluminum component in high entropy alloy Al0.3CrMnFe1.5Nix might react with the solution, leading to a serious localized corrosion on the alloy surface, but the added Ni element would enhance the integrity of the passive film. It is therefore necessary to increase the nickel content to 1 molar to improve the corrosion resistance of this alloy in sulfuric acid solutions. According to analyses by electrochemical impedance spectroscopy (EIS), the improvement resulted from the formation of nickel oxide and the accompanied passivity on the alloy surface. Through microanalyses, we were also able to observe the enhanced corrosion resistance by scanning electron microscopy.