Structural, Compositional, and Mechanical Characterization of WxCryFe1-x-y Layers Relevant to Nuclear Fusion, Obtained with TVA Technology.

Mihail Lungu,Paul Dinca,Oana Gloria Pompilian,Cornel Staicu,Ioana Porosnicu,Parau Anca Constantina,Bogdan Butoi,Alin Velea,Ion Tiseanu,Cristian Lungu,Corneliu Porosnicu,Flaviu Baiasu

doi:10.3390/ma12244072

Abstract

Reduced activation ferritic and martensitic steel like EUROFER (9Cr-1W) are considered as potential structural materials for the first wall of the future next-generation DEMOnstration Power Station (DEMO) fusion reactor and as a reference material for the International Thermonuclear Experimental Reactor (ITER) test blanket module. The primary motivation of this work is to study the re-deposition of the main constituent materials of EUROFER, namely tungsten (W), iron (Fe), and chromium (Cr), in a DEMO type reactor by producing and analyzing complex WxCryFe1−x−y layers. The composite layers were produced in laboratory using the thermionic vacuum arc (TVA) method, and the morphology, crystalline structure, elemental composition, and mechanical properties were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-X-ray fluorescence (micro-XRF), and glow discharge optical emission spectrometry (GDOES), as well as nanoindentation and tribology measurements. The results show that the layer morphology is textured and is highly dependent on sample positioning during the deposition process. The formation of polycrystalline WxCryFe1−x−y was observed for all samples with the exception of the sample positioned closer to Fe anode during deposition. The crystalline grain size dimension varied between 10 and 20 nm. The composition and thickness of the layers were strongly influenced by the in-situ coating position, and the elemental depth profiles show a non-uniform distribution of Fe and Cr in the layers. The highest hardness was measured for the sample positioned near the Cr anode, 6.84 GPa, and the lowest was 4.84 GPa, measured for the sample positioned near the W anode. The tribology measurements showed an abrasive sliding wear behavior for most of the samples with a reduction of the friction coefficient with the increase of the normal load.

Highlights

In the last 50 years, the fast development of civilization combined with the need for reducing the CO2 emissions worldwide determined an increasing demand for a cleaner energy, both in the household and in the industrial sector
The future design of the International Thermonuclear Experimental Reactor relies on the selection of the proper materials as first-wall materials [3]
The Wx Cry Fe1−x−y layers that present a high interest in the nuclear fusion domain were co-deposited by means of the thermionic vacuum arc (TVA) method

Summary

Introduction

In the last 50 years, the fast development of civilization combined with the need for reducing the CO2 emissions worldwide determined an increasing demand for a cleaner energy, both in the household and in the industrial sector. Researchers worldwide make considerable efforts to further develop new types of energy sources in order to overcome the need for a cleaner energy and to reduce today’s growing dependence on fossil fuels [1]. One of the several challenges regarding the production of fusion energy on Earth is represented by the determination of materials to be integrated in the blanket modules and as plasma facing components (PFC).

Methods

Results

Conclusion