Obtenção de filmes finos de ligas de alta entropia à base de CoFeNi por eletrodeposição em meio aquoso

Abstract

High-entropy alloys, also called multicomponent alloys, are alloys that have five or more elements whose composition is formed between 5% and 35% in terms of atomic composition of the elements. These alloys have gained prominence recently because they present very distinct and attractive properties in relation to conventional alloys composed of a single major element. In this context, the alloys have been produced by different physical and chemical methods. The present work addresses the subject of obtaining thin films of high-entropy alloys based on CoFeNi by the electrodeposition technique in aqueous medium, with additions of elements such as Mo, Mn, Sn and W. A simple and low-cost technique in relation to other methods proposed in the literature. By using the direct current (galvanostatic) method at room temperature and by varying the current density to obtain thin films in a range of 5 to 100 mA/cm2, the high entropy alloy CoFeNiMoW and the possibility of obtaining the CoFeNiMnSn alloy on a brass substrate (CuZn) are demonstrated. The electrodeposited films are characterized by Energy Dispersive Spectroscopy (EDS), Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD) and Mossbauer Spectroscopy techniques. EDS analyses reveal that the composition of the alloys is strongly influenced by the applied current density. In the high entropy alloy with five elements CoFeNiMoW formed from applied current density of 50 mA cm-2, the atomic proportion obtained is Co 30%, Fe 21%, Ni 19%, Mo 25%, W 5%. For the CoFeNiMnSn alloy, its composition formed by means of a current density equal to 50 mA cm-2 is Co 26.2%, Fe 33.8%, Ni 5.5%, Mn 1.8%, Sn 32.6%, thus evidencing the formation of alloys with five elements by the proposed method.