Effects of Al or Mo Addition on Microstructure and Mechanical Properties of Fe-Rich Nonequiatomic FeCrCoMnNi High-Entropy Alloy

Shuliang Wang,Qilin Li,Luyu Chen,Shidong Wang,Mingyu Wu,Dinghan Xiang,Shuiyuan Yang

doi:10.3390/met12020191

Abstract

In this work, a Fe-rich nonequiatomic Fe40Cr15Co15Mn10Ni20 high-entropy alloy was successfully prepared based on phase analysis and cost reduction. Fe40Cr15Co15Mn10Ni20 high-entropy alloy with a single-phase face-centered cubic (FCC) structure was strengthened by the addition of 11 at.% Al or 10 at.% Mo, and the variations of phase and mechanical properties of the strengthened alloys were subsequently investigated. It has been found that the addition of 11 at.% Al led to the formation of FCC and body-centered cubic (BCC) dual-phase structure in the Fe40Cr15Co10Mn4Ni20Al11 alloy, while its yield strength (σ0.2) and tensile strength increased from 158 ± 4 MPa and 420 ± 20 MPa to 218 ± 7 MPa and 507 ± 16 MPa, respectively, as compared to the single-phase FCC structure Fe40Cr15Co15Mn10Ni20 alloy. The addition of 10 at.% Mo introduced intermetallic compounds of μ and σ phases, which resulted in improved yield strength of 246 ± 15 MPa for the Fe40Cr15Co10Mn5Ni20Mo10 alloy. However, the alloy exhibited premature brittle fracture due to the existence of a large number of intermetallic compounds, which led to deteriorated tensile strength of 346 ± 15 MPa. The findings of this work suggest that the introduced secondary phases by the addition of Al and Mo can effectively strengthen the high-entropy alloy; however, the number of intermetallic compounds should be controlled to achieve a combination of high strength and good ductility, which provides a reference for the follow-up study of nonequiatomic high-entropy alloys.

Highlights

The design and research of traditional alloys have long been limited to the idea of using one or two principal elements as the matrix which is supplemented with additional minor elements to adjust the performance [1–4]
Conventional wisdom holds that high-entropy alloys (HEAs) consist of five or more principal elements with each contributing 5 at.% to 35 at.%, usually at an equal atomic ratio or near equal atomic ratio [5–9]
face-centered cubic (FCC) plus body-centered cubic (BCC) structure owing to the lattice distortion as a result of the incorporation of Al

Summary

Introduction

The design and research of traditional alloys have long been limited to the idea of using one or two principal elements as the matrix which is supplemented with additional minor elements to adjust the performance [1–4]. The traditional alloy design concept was challenged since the design concept of high-entropy alloy (HEA) was proposed and the HEA was successfully prepared. Conventional wisdom holds that high-entropy alloys (HEAs) consist of five or more principal elements with each contributing 5 at.% to 35 at.%, usually at an equal atomic ratio or near equal atomic ratio [5–9]. The mixing entropy of the solid solution phase in the high-entropy alloy is much higher than that of the intermetallic compound at elevated temperatures. High-entropy alloys have delayed diffusion and Licensee MDPI, Basel, Switzerland

Methods

Results

Discussion

Conclusion