Investigation of the Oxidation Behavior of Cr20Mn17Fe18Ta23W22 and Microdefects Evolution Induced by Hydrogen Ions before and after Oxidation.

Bao-Zhen Wu,Kun Zhang,Fu-Jun Gou,Xing-Zhong Cao,Zhao-Ming Yang,Te Zhu,Yuan Wang

doi:10.3390/ma15051895

Bao-Zhen Wu, Kun Zhang + Show 5 more

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https://doi.org/10.3390/ma15051895

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Abstract

The oxidation behavior of body-centered cubic (bcc) structure Cr20Mn17Fe18Ta23W22 refractory high-entropy alloy (RHEA) and the microdefects induced by hydrogen ions before and after oxidation were investigated. The results revealed that compared with oxidizing Cr20Mn17Fe18Ta23W22 at 800 °C (6.7 °C/min) for 4 h (ST3, Ar:O2 = 3:1), the heating procedure of oxidizing Cr20Mn17Fe18Ta23W22 at 300 °C (6 °C/min) for 2 h and then increased to 800 °C (5 °C/min) for 4 h is more conducive to the production of oxides without spalling on the surface, i.e., HT1 (Ar:O2 = 1:1), HT2 (Ar:O2 = 2:1) and HT3 (Ar:O2 = 3:1) samples. The oxidation of Cr20Mn17Fe18Ta23W22 RHEA is mainly controlled by the diffusion of cations instead of affinities with O. Additionally, HT1 and HT3 samples irradiated with a fluence of 3.9 × 1022 cm−2 hydrogen ions (60 eV) were found to have a better hydrogen irradiation resistance than Cr20Mn17Fe18Ta23W22 RHEA. The microdefects in irradiated Cr20Mn17Fe18Ta23W22 mainly existed as hydrogen bubbles, hydrogen-vacancy (H-V) complexes and vacancy/vacancy clusters. The microdefects in irradiated HT3 were mainly vacancies and H-V complexes, while the microdefects in irradiated HT1 mainly existed as vacancies and vacancy clusters, as large amounts of hydrogen were consumed to react with oxides on the HT1 surface. The oxides on the surface of the HT3 sample were more stable than those on HT1 under hydrogen irradiation.

Highlights

The GIXRD pattern of Cr20 Mn17 Fe18 Ta23 W22 refractory high-entropy alloy (RHEA) revealed that the structure of the as-deposited Cr20 Mn17 Fe18 Ta23 W22 was a BCC phase (Figure 1a)
The BCC peak had a significant broadening as the grain of Cr20 Mn17 Fe18 Ta23 W22 RHEA was nanocrystalline and the grain size was ~9 nm
A Cr20 Mn17 Fe18 Ta23 W22 RHEA coating was fabricated via magnetron sputtering

Summary

Introduction

Hydrogen isotopes (deuterium and tritium) are the primary fuel for nuclear fusion; the migration and retention of hydrogen in structural materials affect the fuel efficiency, which could lead to hydrogen embrittlement [1–5]. Research on preparing stable hydrogen permeation barriers to reduce hydrogen solubility and diffusivity has become an important issue in the study of nuclear materials [6–9]. To simulate the bombardment of the material in the fusion reactor by hydrogen isotopes plasma, hydrogen irradiation experiments have been conducted and investigated by researchers [10,11]. Hydrogen irradiation often produces lots of vacancy type defects, like vacancy and H-V complexes. These defects lead to irreversible plastic deformation of materials. Investigating the evolution of defects caused by hydrogen irradiation is crucial for the development of fusion reactor material.

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