The Microstructure and Mechanical Properties of Refractory High-Entropy Alloys with High Plasticity.

Yiwen Chen,Chao Wu,Xingwang Cheng,Bo Cheng,Ziqi Xu,Yunkai Li

doi:10.3390/ma11020208

Abstract

Refractory high-entropy alloys (RHEAs) are promising materials used at high temperature, but their low plasticity restricts their application. Based on the valence electron concentration (VEC) principle, four kinds of RHEAs (ZrTiHfV0.5Nb0.5, Zr2.0TiHfVNb2.0, ZrTiHfNb0.5Mo0.5, and ZrTiHfNb0.5Ta0.5) are designed (VEC < 4.5). The experimental results show that the plasticity of these alloys was greatly improved: the static compressive strain was higher than 50% at room temperature (RT), and some elongations were produced in the tensile process. Moreover, the microstructure and phase composition are discussed in detail. The addition of Nb, Mo, and Ta contributed to the high-temperature strength. Finally, the dynamic mechanical properties of these RHEAs with coordination between strength and plasticity are investigated.

Highlights

In recent years, a great number of new ideas have emerged in alloys [1]
Because of the high configuration entropy in some Refractory high-entropy alloys (RHEAs), the solid solution phase with the lowest energy can stay stable at room temperature (RT) [18,19]
ZrTiHfNb0.5Mo0.5, and ZrTiHfNb0.5Ta0.5) were designed by controlling the valence electron concentration (VEC), and they were synthesized via vacuum arc melting in order to certify the accuracy of the VEC principle

Summary

Introduction

High-entropy alloys (HEAs) were proposed by Yeh et al [2,3], and have attracted much attention because of their extraordinary properties. HEAs are composed of five or more elements with equal or near-equal mole ratios (5–35 at %). In contrast with traditional theories, HEAs form a simple crystal structure for their high entropy. These alloys have good corrosion resistance [4,5], high hardness [6], and excellent thermal stability [7]. Refractory high-entropy alloys (RHEAs) display good mechanical properties at a high temperature [8,9,10], as they contain refractory elements (Zr, Ti, Hf, V, W, Ta, Mo, et al.)

Methods

Results

Conclusion