Choudhary, SO'Brien, SQiu, YThomas, SGupta, R KBirbilis, Nick2023-03-052023-03-051388-2481http://hdl.handle.net/1885/286593Recent exploration of multi-principal-element alloys (MPEAs), which include the so-called high-entropy alloys, has revealed hitherto unreported properties and phenomena arising from investigation of broader compositional space. Herein, a low cost and lightweight alloy (equiatomic AlFeMnSi) is presented that exhibits exceptional corrosion resistance in 0.6 M NaCl solution, despite a multiphase structure and the absence of well-known passivating elements (such as Cr, Mo, Ti and Nb). In-line inductively-coupled plasma mass spectroscopy (ICP-MS) analysis of alloy dissolution and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) of the surface film revealed that the alloy passivates by a unique mechanism involving dissolution–precipitation of Si. The dynamic precipitation of a Si hydroxide surface film results in excellent passivity of the alloy, revealing the possibility of developing low-cost corrosion-resistant alloys from metals available from waste streams.The authors gratefully acknowledge the use of facilities in Monash Centre for Electron Microscopy (MCEM), the Monash Analytical Plat- form and the Monash X-ray Platform (MXP). RKG and NB gratefully acknowledge the support of ONR Project N00014-17-1-2807 with Dr. Airan Perez as program officer. SC is supported by an MGS scholarshipapplication/pdfen-AU© 2021 The authorshttp://creativecommons.org/licenses/ by-nc-nd/4.0/Multi-principal-element alloyPassivityCorrosionMetallurgyICP-MSAR-XPS202110.1016/j.elecom.2021.1069892021-12-26Creative Commons Attribution licence