Investigation of micro and nanostructure on porous high-entropy alloy surface influences its hydrophobicity

Abstract

The micro and nanostructures of materials have an important effect on the wettability of materials' surfaces. For AlCoCrFeNi 2.1 and AlCoCrFe Ni High-entropy alloy, the special porous micro and nanostructure can be fabricated by electrochemical dealloying in 5 wt.% sulfuric acid solution aiming to improve the hydrophobicity of the material surface. The surface crystal structure of the prepared porous HEAs was characterized by X-ray diffraction, the micromorphologies were characterized by a Scanning electron microscope, and the static water contact angles were measured by a contact angle goniometer. The results showed that AlCoCrFeNi 2.1 HEA showed nanoscale pores and smooth surfaces, while AlCoCrFeNi HEA showed microscale pores but rough surfaces generated from nanoscale short rod-like particles. AlCoCrFeNi 2.1 HEA showed FCC (Fe-, Cr-and Ni-rich) and BCC (Al-and Ni-rich) dual phase structures and AlCoCrFeNi HEA showed BCC (Al-and Ni-rich) and B2 (Fe-and Cr-rich) phase structure. The prepared porous AlCoCrFeNi HEA possessed quite good hydrophobicity than that of AlCoCrFeNi 2.1 HEA, and this can be explained as the result of the "lotus effect" formed by the aggregation of nanoscale short rod-like particles.