High temperature oxidation and hot corrosion behaviors of Fe65.7Ni11.7Ti1Mo6.6Co15 high entropy alloy

Understanding the surface oxidation and hot corrosion properties of the Fe65.7Ni11.7Ti1Mo6.6Co15 high entropy alloy (HEA) at high temperatures and hot corrosion media could provide useful insights into designing the high performance of the metallic materials, which is indispensable for its wide applications. Herein, at about 1923 K, the HEA was prepared by vacuum induction melting with five principal metals (Fe, Ni, Ti, Mo, and Co) in the solid-solution form. The high temperature oxidation tests at 823 K, 923 K, and 1023 K, and the hot corrosion tests using mixtures of NaCl and Na2SO4 as the hot corrosion media at 923 K were carried out, respectively. High temperature oxidation and hot corrosion behaviors were investigated via surface and cross-section morphologies observation, oxidation and corrosion products tests, and chemical composition distribution maps analysis. The effect of temperature on the oxidation resistance, as well as the effect of the content of NaCl in the mixed salt medium on the hot corrosion resistance were revealed. The results show that the HEA exhibited good high temperature oxidation resistance at 923 K according to mass gain and products after oxidation. The higher content of NaCl in the mixed salt medium can bring more intense hot corrosion. In addition, more oxygen and molten salts can be migrated via cracks and dense pores, which is not conducive to enhancing the high temperature oxidation resistance and hot corrosion resistance.