Microstructure and Corrosion Resistance of a Novel AlNiLa Lightweight Medium Entropy Amorphous Alloy Composites

Abstract

A new type of lightweight AlNiLa medium entropy amorphous alloy composite ribbons (labled as MEAAC ribbons) were prepared by vacuum arc melting technology and high-speed single roller melt-spinning method. The microstructure and thermal stability of MEAAC ribbons were examined using X-ray diffraction, differential scanning calorimeter, and scanning electron microscope. Meanwhile, the hardness and surface roughness of these ribbons were measured by Vickers microhardness tester and atomic force microscope. The potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) were applied to investigate the corrosion behavior of these MEAAC ribbons in simulated seawater (3.5wt% NaCl corrosive solution) at room temperature. The results demonstrate that AlNiLa MEAAC ribbons in the as-received state are mainly composed of amorphous phase and intermetallic compounds. The hardness values of all melt-spun ribbons are above 310 HV_0.1. With the increase of Al content, the linear polarization resistances of four various AlNiLa MEAAC ribbons are negligibly different numerically. It is also found that Al₄₅Ni_27.5La_27.5 MEAAC ribbons have the most positive corrosion potential and the smallest corrosion current density at the same time; hence it may be a kind of potential material for metal surface protection in harsh ocean environment.

Keywords

medium entropy amorphous alloy composites / rapid solidification / microstructure / corrosion resistance / thermal stability