7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

High Entropy Alloys In Advanced Nuclear Fusion Applications
Maryna Bilokur1, Surinder Singh2, Ashok Meghwal2, Matt Thompson1, Andrew S. M. Ang2, Frank
Brink1, Christopher C. Berndt2 and Cormac Corr1
1
Department of Materials Physics, Research School of Physics, Australian National University,
2
Industrial Transformation Training Centre on “Surface Engineering for Advanced Materials”,
Swinburne University of Technology
e-mail (speaker): maryna.bilokur@anu.edu.auThe safety and reliability of tokamak fusion reactors
rely on the successful design and fabrication of advanced
structural materials resilient to the incident flux ofhelium and neutron particles at both low and hightemperatures (>700°C). While some traditional
refractory materials, such as tungsten (W), have been
considered for application in the first wall and divertor
region of tokamaks due to their suitable properties—suchas a high melting point, low tritium (T) retention, andfavorable mechanical response—they experienceintergranular brittle failure due to the accumulation ofhelium bubbles and susceptibility to neutron-induced
swelling and embrittlement. The new quest in fusion
reactor material search focuses on overcoming theselimitations by developing a new class of engineering
materials that can withstand the extreme conditions
within the tokamak environment while maintaining
optimal structural integrity and mechanical response toirradiation and high heat loads.
In this work, we address the above limitations bydeveloping a non-conventional class of alloys, highentropy alloys (HEA), based on several principal
elements W, Ta, Mo, Ni, Cr and Mo, Co, Cr, Fe, Ni in thenear-equiatomic composition. The W-based HEA wasgrown as thin film (100 nm) showing a homogeneous
chemical distribution of W, Ta, Mo, Ni and Cr across thedepth of the film. The analysis of the cross-sectional
TEM shows the columnar structure in the as-deposited
W-based high entropy alloy with the columnar size about
5nm. To test the irradiation resilience the HEA samples
were exposed to He ions with the fluence of 1.2 x 1025m-2
in the magnetized plasma interaction experiment(MAGPIE) [1]. No phase separation or elemental
segregation was observed in the irradiated samples asevidenced by the EDS analysis (Figure 1(c)). The Wbased HEA thin film show perseverance of the uniform
elemental distribution and structural integrity without
any distinct sign of He irradiation damage in the form ofobservable microcracks, blistering, or compositional
shifts.
The nanomechanical testing shows large hardness inthe as-deposited HEA films of 20.74 GPa with the nearnegligible irradiation hardening of ~1GPa and ~5GPa in
the irradiated at 500°C and 700°C W-based HEA thinfilms, respectively. The nanoindentation analysis
confirms exceptional radiation tolerance to the Heirradiation damage in W-Ta-Mo-Ni-Cr high entropy alloy
showing promise for applications demanding robustmaterials under extreme conditions.

(a)

(b)

(c)

Figure 1 - Cross-sectional TEM micrograph of (a) asdeposited and (c) He irradiated at 700°C W-Ta-Mo-Ni-Cr
based HEA, (b) elemental distribution of principal
elements across the as-deposited W-Ta-Mo-Ni-Cr thin
film
Treatment
Hardness,
Elastic modulus,
Hv, GPa
E, GPaAs-deposited
500°C He irradiation

20.74
21.34

209.28217.29700°C He irradiation

25.47

219.15

Table 1 - Results for mechanical properties of W-Ta-MoNi-Cr HEA after He irradiation (Elastic modulus, E, andVickers hardness, HV)
References[1] Blackwell, Boyd D., et al. "Design andcharacterization of the Magnetized Plasma Interaction
Experiment (MAGPIE): a new source for plasma–material interaction studies." Plasma Sources Scienceand Technology 21.5 (2012): 055033.