Inducing surface nanoporosity on Fe-based metallic glass matrix composites by selective dealloying

Nanoporosity (i.e. nanohole formation) is induced at the surface of Fe-based metallic glass matrix composites by selective chemical or electrochemical (at 1 V) etching of a Fe65Cu10Zr10B15 composite material using a 0.065 M HNO3 aqueous electrolyte. While electrochemical treatments are found to remove the Cu-rich precipitates present at the surface of this alloy, chemical etching (in absence of applied potential) only causes partial dissolution of the Fe-rich amorphous matrix. In both cases, the resulting pores exhibit random shapes and their lateral size ranges from a few tens to hundreds of nm. The investigated material is ferromagnetic at room temperature, both before and after dealloying and it does not crystallize during the (electro)chemical etching process. The contact angle in deionized water decreases in the dealloyed states in comparison with the as-spun ribbon. This procedure is appealing for applications that could benefit from the combination of increased surface area and the amorphous character (lack of crystallinity) at the surface of dealloyed metallic glass composite materials.