Phase formation and structural evolution of multicomponent (CrFeCo)1-yNy films

Smita G Rao,Robert Boyd,Rui Shu,Arnaud Le Febvrier,Grzegorz Greczynski,Per Eklund

doi:10.1016/j.surfcoat.2021.127059

Abstract

The Cantor alloy (CoCrFeMnNi) and its variants, in bulk as well as thin films, have been extensively studied. They are known to exhibit cubic crystal structures and thermodynamic stability regardless of their complex chemical composition. Therefore, they may find use as hard, wear-resistant, corrosion and oxidation-resistant coatings. The addition of light elements, such as nitrogen, is known to help improve these properties further through processes such as amorphization and nitride compound formation. Here, we investigate the ternary CrFeCo system to study the effects of nitrogen addition. (CrFeCo) 1-y N y multicomponent thin films are grown on silicon substrates by DC magnetron sputtering. Changes in crystal structure, morphology, mechanical and electrical properties with gradual increases of nitrogen in the film are described and discussed. Increased addition of nitrogen from 14 at.% to 28 at.% in the film leads to a transformation from an fcc to a bcc crystal structure, affects both the mechanical and electrical properties. XPS analysis shows the tendency of nitrogen to bond with Cr over other metals. The films display hardness values between 7 and 11 GPa with resistivities values ranging between 28 and 165 μΩ cm. • Multicomponent (CrFeCo)Ny coatings deposited by reactive magnetron sputtering • Effect of nitrogen content on structure, morphology and composition was studied. • Phase formation and evolution with changes in nitrogen content • Mechanical and electrical properties of (CrFeCo)Ny thin films

Highlights

The need for materials that enhance life span, performance, and economic viability among various other properties has propelled research in alloy design from traditional binary to more complex sys tems multicomponent alloys
The present study aims to understand the role played by small amounts of nitrogen on the crystal structure, morphology, and mechanical properties of 3d transition metal (Cr, Fe and Co) multi component thin films
Differentiating between the individual metals (Cr, Fe, Co) in the ToF-ERDA measurement data was not possible due to signal overlap

Summary

Introduction

The need for materials that enhance life span, performance, and economic viability among various other properties has propelled research in alloy design from traditional binary to more complex sys tems multicomponent alloys. The concept of multicomponent and high entropy alloys (HEA) was theoretically conceived in the 1980s [1,2]. HEAs form stable solid solutions due to low Gibbs free energy (ΔG) resulting in a high entropy of mixing (ΔSmix). The same reasoning is not completely applicable to all multi component alloys, a concept which includes a broader selection including but not limited to HEAs. Multicomponent alloys are attractive candidates for industrial applications because of the formation of stable solid solutions and due to the combination of properties that can be achieved [5,6]. Trends in current research which are shifting from bulk alloys to thin films brings the requirement of an in-depth knowledge on growth processes, phase formation, physical and chemi cal properties [3,7,8]

Results

Discussion

Conclusion