Ministry of Education, Culture, Sports, Science and Technology Grant-in-Aid“Scientific Research on Innovative Areas” for FY2018-22
NEWSLETTERVol.

High Entropy Alloys

42022 MAY

Science of New Class of Materials Based on
Elemental Multiplicity and Heterogeneity

Introduction to Publicly Offered Research Teams
New Teams Boost up the Second Half of the HEA ProjectA01

Low-density high entropy alloys composed of Group 1 and 2 elements

Shigehito Isobe (Hokkaido University), Hirotada Hashimoto (Hokkaido University), Hiroshi Oka (Hokkaido University),
Naoyuki Hashimoto (Hokkaido University)

Our target is low-density high entropy alloys (HEAs) mainly composed ofGroup 1 and 2 elements. Most of the existing or currently researched highentropy alloys, including Cantor alloys, are mainly composed of transition
metal elements. There are few reports on the HEAs mainly composed of alkali
metals and alkaline earth metals, because the alloys with alkali metals andalkaline earth metals are less likely to form solid solution. In this research, we
try to synthesize low-density HEAs by mechanical alloying. As an example, wehave succeeded to synthesize new alloys composed of Li, Mg, Al, and Ti. From
the results of XRD and SEM-EDS (Figure), it has been indicated that a solid
solution single phase (FCC structure) of LiMg0.5AlTi1.5 was obtained. As
applications, functional materials such as next-generation light metal materials
and hydrogen storage materials can be considered. Now, we are trying tosynthesize quinary HEAs composed of light elements.

A01

Mg

Ti

Development of novel functional materials in multi-anion high-entropy
compounds

Ryota Shimizu (Tokyo Institute of Technology)

We study the novel functionalities in high-entropy compounds of ionic crystals. Using
non-equilibrium epitaxial thin-film growth techniques such as pulsed laser deposition andreactive magnetron sputtering, we aim for the creation of novel materials that cannot be
synthesized in bulk. There are three topics as follows. (1): synthesis of layered oxide
epitaxial thin films containing four or more transition metal elements[1], (2): synthesis ofhigh-entropy fluoride epitaxial thin films with perovskite and rutile structures, and (3):synthesis of high-entropy multi-anion compounds simultaneously containing four anions(F, N, H, O). We expect this study to develop electrochemical applications such as
high-performance electrode materials and solid electrolytes for lithium and fluoride
batteries, and catalysts for oxygen-evolution reactions in water electrolysis.
Reference:[1]: Wang et al., “Synthesis of High-Entropy Layered Oxide Epitaxial Thin Films: LiCr1/6Mn1/6Fe1/6Co1/6Ni1/6
Cu1/6O2”, Cryst. Growth Des. 22, 1116 (2022).

Al

High Entropy Alloys Introduction to Publicly Offered Research Teams

A01

2022 MAY

Synthesis of nanostructured high entropy alloys by using multicomponenthydroxide nanoparticles

Naoki Tarutani (Hiroshima University), Yuka Hiragi (Hiroshima University), Kazumasa Suzuki (Shiga Prefecture University),
Kiyofumi Katagiri (Hiroshima University)

Synthesis of high-entropy alloys (HEAs) with controlled nanostructures has
been attracted attentions towards highly functional materials. Although HEA
nanoparticles were found to prepare through chemical ion reduction andthermal decomposition of salts, chemical composition are still limited andhard to design the nanostructures. Here we focus on developing a novel
approach to synthesize HEAs with controlled nanostructures using multicomponent hydroxide nanoparticles as precursors. Metal hydroxides are known toform crystals including multi metal elements with homogeneous distribution
by coprecipitation. The figure shown in right panel is a result of tracing thecoprecipitation process in the case of Co and Ni hydroxide nanoparticles.
Conductivity and potential correspond to ion concentration and solution pH,
respectively. With increasing the solution pH triggered by the addition ofreaction initiator, ion concentration decreased, which means formation of
metal hydroxide. Co-Ni system showed intermediate trend of the change ofsolution pH and ion concentration compared to the respective Co and Ni
systems. This indicates formation of binary metal hydroxides. Based on thesolution conductivity and potential measurements, we found to achieve
quinary metal hydroxide nanoparticles. It is expected to obtain HEAs by
reducing the quinary metal hydroxide nanoparticles.

A01

Production of High-Entropy Alloy Nanoparticles by Top-Down and Bottom-Up
Laser Processes

Tomoyuki Yatsuhashi (Osaka City University)

High-entropy alloy nanoparticles (NPs) have been increasingly recognized asimportant catalysts in chemical processes. Various synthetic methods have been
proposed, but there are difficulty originating from the use of complex templates aswell as low production yield. The goal of this study is to synthesize alloy NPs by
top-down and bottom-up laser processes in liquid phase. In bottom-up synthetic
process, alloy NPs are obtained by the confinement and fusion of desired elements.
Laser-induced nucleation is known as fast-heating and fast-cooling processes thatenables to produce noble metal alloy NPs from the corresponding metal ion mixture
solution. However, this method is not applicable to transition metal ions. We succeeded to synthesize transition metal NPs by using metal complex solution as reactants,
but the synthesis of alloy NPs is underway. In the case of top-down laser process,NPs are obtained by the ablation of bulk alloy materials in liquid medium. We
constructed new optical set-up using a galvamo mirror system to scan the laser
beam. FeCoNi medium entropy alloy that was produced by electrodeposition waschosen as a sample for laser ablation in water. Colloidal solution of NPs smaller than
10 nm in diameter was easily separated from bulk starting materials (picture).

High Entropy Alloys Introduction to Publicly Offered Research Teams

A01

2022 MAY

Robustness of superconductivity in HEA-type metal telluride
AgInSnPbBiTe5 under high pressures

Yoshikazu Mizuguchi (Tokyo Metropolitan University), Md. Riad Kasem (Tokyo Metropolitan University), Yuki Nakahira (Tokyo Metropolitan University),
Aichi Yamashita (Tokyo Metropolitan University), Ryo Matsumoto (NIMS), Hitoshi Yamaoka (RIKEN)

Recently, material development and studies of physical properties of
HEA-type superconductors have been one of hot topics in the field of superconductors. We observed anomalous superconducting states in AgInSnPbBiTe5
under high pressure; the transition temperature (Tc) of AgInSnPbBiTe5 does notchange with pressure in the high-pressure (CsCl-type) phase, which is clearly
different from the pressure dependence of Tc for PbTe, the zero-entropy counterpart [1]. Since the crystal and electronic structures for AgInSnPbBiTe5 and
PbTe are similar under high pressures, we propose that the robust superconductivity is induced by local disordering at the metal-Te bonding states.
[1] Md. Riad Kasem et al., “Robustness of superconductivity to external pressure inhigh-entropy-alloy-type metal telluride AgInSnPbBiTe5”, arXiv:2112.06461.

A01

Nanoporous ultra-high-entropy alloys containing fourteen elements forwater splitting electrocatalysis

Takeshi Fujita (Kochi University of Technology)

The dealloying method was applied as a facile synthetic route to nanoporous
ultra-high-entropy alloys (np-UHEAs) containing up to 14 elements (Al, Ag, Au,
Co, Cu, Fe, Ir, Mo, Ni, Pd, Pt, Rh, Ru, and Ti). TEM analysis of the alloys
indicated a hierarchical, nanoporous, and nanocrystalline fcc structure withuniformly distributed elements. The dealloying strategy shows great potential
for the design and preparation of np-UHEAs as it can accommodate a far greater number of elements than the 14 used in this study. Furthermore, they exhibit
high catalytic activities and electrochemical stabilities in the hydrogen evolution
reaction and oxygen evolution reaction in acidic media, superior to that ofcommercial Pt/graphene and IrO2 catalysts. This study not only provides thebasis for prospecting and designing np-HEAs with diverse compositions andstructures, but also provides unprecedented opportunities for element selection
for fabricating an omnipotent catalyst for various applications [1].
[1] Z. X. Cai, H. Goou, Y. Ito, T. Tokunaga, M. Miyauchi, H. Abe, T. Fujita, Nanoporous ultra-high-entropy alloys containing fourteen elements for water splitting
electrocatalysis, Chemical Science 12 (2021) 11306-11315.

A01

Atomic Dynamics in High-Entropy Alloys Investigated by Inelastic X-ray and
Neutron Scattering

Satoshi Tsutsui (JASRI), Kazuki Iida (CROSS), Ryoichi Kajimoto (JAEA), Masato Matsuura (CROSS), Takeshi Teramoto (Kobe University),
Mohamad Qayyumbin Mohamad Izlan (Kobe University), Ryota Shimohara (Kobe University), Katsushi Tanaka (Kobe University)

Phonon dispersion relations reflect elasticities of materials on microscopic viewpoints.
Inelastic X-ray scattering (IXS) and inelastic neutron scattering (INS) techniques arecomplementary to investigate phonon dispersion relations. Since X-rays (neutrons) arescattered by electrons (nuclei), comparison of dynamical structure factor corresponding
to phonon dispersion relations between IXS and INS techniques sometimes provides
element-specific phonon dispersion relations. In particular, the comparison of dynamical
structure factors between IXS and INS is helpful to understand contributions of eachelement to the elasticities of high-entropy alloys consisting of atoms whose atomic
numbers are close among them. We have successfully obtained the dynamical structure
factors in CrCoNi and CrMnFeCoNi with IXS at BL35XU in SPring-8 and INS at BL01 in
J-PARC MLF. The microscopic elasticity estimated from the dynamical structure factors
quantitatively agree with the macroscopic elasticity reported previously.

High Entropy Alloys Introduction to Publicly Offered Research Teams

A01

2022 MAY

Effect of stacking fault energy on irradiation damage in Co-free highentropy alloys

Naoyuki Hashimoto (Hokkaido University), Eyo Wada (Hokkaido University), Keisuke Fukumoto (Hokkaido University), Hiroshi Oka (Hokkaido University),
Shigehito Isobe (Hokkaido University)[1] N.Hashimoto, T.Fukushi, E.Wada, and W-Y.Chen: J. Nucl. Mater., 545 (2021),
152642.

A01

FeCr0.8NiMn1.3

FeCr0.8Ni1.3Mn1.3 FeCr0.8Ni1.5Mn1.5

WBDF

FeCr0.8NiMn

DF from relrod

In order to investigate the effect of stacking fault energy on
microstructural evolution [1] in reduced activation high entropy
alloys, electron and/or Au+ ion irradiation was performed to theCo-free FCC-type FeCr0.8NixMny (x, y = 1, 1.3, 1.5) alloys. TEM
observation of the 5%-deformed FeCr0.8NixMny alloys revealed theincrease in the stacking fault energy with increasing both Ni and
Mn concentration. In addition, FeCr0.8Ni1.5Mn1.5 had the highest
stacking fault energy, which was much higher value than that of
316SS. Furthermore, the yield strength and the elongation of
deformed FeCr0.8NixMny also showed the Ni and Mn concentration
dependence. It seems that s0.2, UTS, and e t are slightly increasing
with increasing Mn and Ni contents, while, the 0.2% proof
stress (s0.2), the ultimate tensile strength (UTS), and the total
elongation (e t) were comparable to that of 316H stainless steel. The
electron irradiation at 400 ºC resulted in the formation of black
dots, self-interstitial atom faulted loops, but no observable voids inall the FeCr0.8NixMny alloys. The comparison of microstructural
evolution revealed less faulted Frank loop formation in
FeCr0.8Ni1.3Mn1.3 and FeCr0.8Ni1.5Mn1.5 alloys. From these results,
it is suggested that FeCrNiMn-based Co-free high entropy alloys
would be developed as high irradiation resistant materials bycontrolling the stacking fault energy with optimized element
concentration.

Average size
48 nm
Density
2.9 x 1021 m-3

Average size
30 nm
Density
1.6 x 1021 m-3

Average size
40 nm
Density
1.1 x 1021 m-3

Local Structural Analysis in High-Entropy Alloys by using Synchrotronradiation X-ray.

Noriaki Hanasaki (Osaka University)

The high/medium-entropy alloys (HEA/MEAs) are promising materials fortheir high strength. Since the HEA/MEAs contain many kinds of element in
the same ratio, the conventional solvent-solute-atom concept cannot beapplied. Recently, it is suggested theoretically that some specific elements
such as Cr have large atomic displacement and their displacements haverelation with the strength of the HEA/MEAs. In order to clarify the element’s
character and the local structure in HEAs experimentally, we observed the
EXAFS (Extended x-ray absorption fine structure) in CrCoNi, and found thatthe local disorder in Cr sites is larger than in other constituent element sites[1]. This experimental result is consistent with the large Cr displacement
predicted by the previous first-principle calculations. By the systematic study
in various alloys, we will reveal a global element dependence of the local
disorder and the atomic displacement.
[1] N.Hanasaki et al., AIP Advances 11, 125216 (2021).

Average size
50 nm
Density
8.7 x 1020 m-3

High Entropy Alloys Introduction to Publicly Offered Research Teams

A02

2022 MAY

Intermittent Inelastic deformation in High-Entropy Alloys

Tomoaki Niiyama (Kanazawa University)

The inelastic deformation has an intermittent and critical nature
characterized by power-law statistics. For instance, a wide rangeof acoustic emissions, stress drops, and strain bursts can bemeasured in plastic deformation. The fracture can also showintermittent behavior. Our molecular dynamics simulation revealed
the details of the intermittent plasticity in crystals and metallic
glasses [1–3]. The intermittent dynamics of cleavage failure (crack
propagation in a single crystal) were also confirmed [4]. This study
aims to elucidate the influence of the variety of atom sizes, atypical feature of high-entropy alloys (HEAs), on the intermittent
dynamics of their inelastic deformation. This approach may bring abetter understanding of the excellent mechanical properties of
HEAs from the view of the critical feature and atomic-scale
dynamics.

Intermittent crack propagation by dislocation emissions [4].

Intermittent stress drops and avalanches
in metallic glass [3].
Power-lawstatistics [2].

[1] T. Niiyama, T. Shimokawa, Physical Review E, 91, (2015), 022401.
[2] T. Niiyama, T. Shimokawa, Physical Review B, 94, (2016), 140102.
[3] T. Niiyama, M. Wakeda, T. Shimokawa, and S. Ogata, Physical Review E,
100, (2019), 043002.
[4] T. Niiyama, T. Shimokawa, T. Fujimoto, Journal of the Society of Materials Science, Japan., 67 (2), (2018), 222–228.

A03

High-Entropy Oxides as Active Photocatalysts for CO2 Conversion

Saeid Akrami (Nagoya Institute of Technology), Yasushi Murakami (Kyushu University), Monotori Watanabe (Kyushu University), Tatsumi Ishihara (Kyushu
University), Makoto Arita (Kyushu University), Masayoshi Fuji (Nagoya Institute of Technology), Kaveh Edalati (Kyushu University)

Photocatalytic conversion of CO2 to reactive gasses such as COand fuels under sunlight is a clean technology to reduce the amountof CO2. In a recent study [1], a high-entropy oxide (HEO),
TiZrNbHfTaO11, was introduced as a new photocatalyst for CO2
conversion. The HEO, which had dual phases and various structuraldefects, showed simultaneous photocatalytic activity for CO2 to CO
and H2O to H2 conversion without the addition of a co-catalyst. The
photocatalytic activity of HEO for CO2 conversion was better thanconventional photocatalysts such as anatase TiO2 and BiVO4 andcomparable with P25 TiO2 as a benchmark photocatalyst. The study
confirmed the high potential of HEOs as a new type of photocatalysts for CO2 conversion.

Fig. 1. High-entropy oxide with high photocatalytic activity for CO2
to CO conversion.

[1] S. Akrami, Y. Murakami, M. Watanabe, T. Ishihara, M. Arita, M. Fuji, K. Edalati, “Defective high-entropy oxide photocatalyst with high activity for CO2 conversion”,
Applied Catalysis B, 303 (2022) 120896.

Activities of Young Researchers

Enthusiasm and flexible thinking of young researchers elucidate the essenceof high-entropy alloys!

Fundamental investigation on deformation behavior of Cr-Co-Ni edium-entropy alloys
Zhenghao Chen (Kyoto University), Le Li (Kyoto University), Kyosuke Kishida (Kyoto University), Haruyuki Inui (Kyoto University)

The considerable interests in Cr-Co-Ni medium-entropy alloys (MEAs) with face-centered cubic (fcc) structure are (1) the
highest strength among quaternary and ternary MEA derivatives of the Cr-Mn-Fe-Co-Ni HEA system, and (2) the excellent tensile
ductility that increases with decreasing temperature. In
order to figure out the origin of the fascinating mechanical properties, Group A01(a) makes comprehensive
investigations on Cr-Co-Ni and derivative MEAs basedon the knowledge of dislocation theory in following threeparts: (i) The relationship between the novel solid
solution parameter Mean Square Atomic Distance(MSAD) and the strength, (ii) The relationship among
the Stacking Fault Energy (SFE), twinning deformationand the tensile ductility, and (iii) The effect of the Short
Range ordering (SRO) on mechanical properties [1]. The
aim of this group is to make comprehensive understanding on mechanical properties in H/MEAs based on
dislocation theory and to hence establish an alloy-design
guideline for structural fcc-H/MEAs achieving highstrength and high ductility simultaneously.

[1] L. Li, Z.H. Chen, S. Kuroiwa, M. Ito, K. Kishida, H. Inui, E.P. George: “Tensile and compressive plastic deformation behavior of medium-entropy
Cr-Co-Ni single crystals from cryogenic to elevated temperatures”, International Journal of Plasticity, 148 (2022), 103144.

Contact information:
Zhenghao Chen, Assistant professor
Department of Materials Science and Engineering,
Graduate School of Engineering, Kyoto University
Yoshida-hommachi, Sakyo-ku, Kyoto 606-8501, JAPANTel : +81-75-753-5481
E-mail : chen.zhenghao.6e@kyoto-u.ac.jp◆Our current interests are the origin of the chemical short range ordering (SRO) in
fcc-H/MEAs and its influence on mechanical properties. The further in-depth understanding of SRO is believed to make contributions to achieving better strengthductility balance in structural H/MEAs.

High Entropy Alloys Activities of Young Researchers

2022 MAY

Essential characteristics of strengthening mechanisms in high/medium entropy alloys:
From the viewpoint of heterogeneity on atomic-scale
Shuhei Yoshida (Kyoto University)

High entropy alloys (HEAs) and medium entropy alloys (MEAs) are novel classes of solid solution alloys having five or more andfour or fewer constituent elements, respectively, with near equi-atomic fractions. Among them, HEAs and MEAs with facecentered cubic (FCC) structure have been known to
exhibit an exceptional balance of strength and ductility ina wide range of temperatures ranging from room
temperature to cryogenic temperatures. A series of ourstudies (Ref. [1] for instance) revealed that FCC HEAs
and MEAs showed significantly high friction stress(fundamental resistance to dislocation motion in solid
solutions), contributing to their high yield strength as wellas high tensile strength. The high friction stressobserved in FCC HEAs and MEAs was mainly attributed
to elastic interaction between the elastic field of edge
dislocations and large size misfits of alloying elements(severe lattice distortion) owing to the difference in theatomic sizes. The results suggest that the heterogeneity
on atomic-scale (i.e., different elements with different
sizes occupy different lattice sites) in HEAs and MEAs
plays an essential role in determining their mechanicalproperties.

[1] S. Yoshida, T. Ikeuchi, T. Bhattacharjee, Y. Bai, A. Shibata, N. Tsuji: “Effect of elemental combination on friction stress and Hall-Petch relationship in
face-centered cubic high / medium entropy alloys”, Acta Materialia, 171 (2019), 201.

Contact information:
Shuhei Yoshida, Assistant professor
Department of Materials Science and Engineering,
Graduate School of Engineering, Kyoto University
Yoshida Honmachi, Sakyo-ku, Kyoto, 606-8501, JAPAN
Tel: +81-75-753-5485
E-mail: yoshida.shuhei.5s@kyoto-u.ac.jp
URL: https://researchmap.jp/syoshida1992◆I’m currently working on experimental studies on physical metallurgy andmechanical/physical properties of various solid solution alloys including high/medium entropy alloys. I’m particularly interested in the relationship between microstructure evolution and macroscopic properties of alloys and in characterizing microstructures by using electron microscopy and quantum beam techniques.

High Entropy Alloys Activities of Young Researchers

2022 MAY

Phase separation with ordering in aged Fe-Ni-Mn medium entropy alloy
Fei Sun (Nagoya University), Goro Miyamoto (Tohoku University), Yikun Liu (Tohoku University), Yuichiro Hayasaka (Tohoku University),
Tadashi Furuhara (Tohoku University)

High- and medium-entropy alloys are currently receiving significant attention. Understanding short-range ordering andnano-scaled phase separation concerning elemental interaction is a key to controlling phase stability for designing high entropy
alloys. To elucidate the interaction between elements and their relationship with ordering and phase separation, it is desirable toinvestigate ternary alloys with a small number of constituent elements. Phase separation and ordering behavior at the atomic
scale have not been investigated in Fe-Ni-Mn alloys, and the effects of elemental interactions on them are still unknown. This
study is focused on the ordering and phase separation during the decomposition of Fe-Ni-Mn medium entropy alloys. Based on
the advanced characterization technologies (spherical aberration-corrected scanning transmission electron microscopy (Cscorrected STEM) and three-dimensional atom probe (3DAP)) combined with statistical thermodynamics calculation, we aim todeepen the understanding of the interactions among constituent elements that affect solid solution stability in HEAs for alloy
design and development. Obvious age hardening occurs after aging at 500 °C for 96 h due to the formation of the L10 orderedphase combined with phase separation. By aging at 400 °C or shorter time, obvious precipitation of the ordered phase is notdetected but the radial distribution functions obtained by 3DAP present that enrichment of Ni and Mn nearby the same kinds ofelement is observed, and this tendency is stronger for Mn. This result suggests that phase separation is induced by Mn clusteringin the early stage of aging. A statistical thermodynamic model of phase stability considering L10 ordered structure is developed.
The analyses using the model suggest that phase separation is not possible in a disordered state at 500 °C, therefore, nucleationof the L10 phase should precede phase separation at this temperature. On the other hand, phase separation is possible even in adisordered state at 400 °C, and ordering further enhances phase separation.

[1] F. Sun, G. Miyamoto, Y. Liu, Y. Hayasaka, T. Furuhara: “Phase separation with ordering in aged Fe-Ni-Mn medium entropy alloy”, Acta Materialia, 223(2022), 117487.

Contact information:
Fei Sun, Specially Appointed Lecturer
Department of Materials Design Innovation Engineering
Graduate School of Engineering
Nagoya University
Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
Tel : +81-52-789-4858
E-mail : sun.fei@material.nagoya-u.ac.jp
URL: https://www.material.nagoya-u.ac.jp/Adachi-lab/WWW/index-eng.html◆Our current interest focuses on the phase stability and elemental interactions of medium/high entropy alloys in terms of phaseseparation and ordering at nano-atomic scales using advanced characterization techniques (e.g. STEM, 3DAP, etc.) and thermodynamic calculations.

High Entropy Alloys Activities of Young Researchers

2022 MAY

Atomistic Study on Dynamic Grain Boundary Segregation and Atom Drag due to Grain
Boundary Migration in High-Entropy Alloys
Kohei Shiotani, Tomoaki Niiyama, Tomotsugu Shimokawa (Kanazawa University)

It has been reported that thermal stability of high-entropy alloys (HEAs) is better than that of pure materials and conventional
dilute alloys, suggesting that activation of grain boundary (GB) migration can be suppressed in HEAs. In order to elucidate themechanism for the excellent thermal stability of HEAs, understanding a detailed atomic-scale behavior of moving GBs is
indispensable. Therefore, we perform molecular dynamics simulations about GB migration with model HEAs and investigate
atomic-scale properties of moving GBs such as dynamic GB segregation in the HEAs. GB migration simulations by loading shear
stress at temperature of 85% of melting point are conducted with equiatomic FeNiCrCoCu-HEAs at various GB velocities. For thecomparison with the obtained results from the HEAs, we also conduct the same analyses with pure Cu as a representative of
single-element materials. As shown in the bottom left figure, the applied shear stress as a driving force required for GB migration
linearly increases with GB velocity in the whole velocity region in pure Cu, while the stress-velocity relation in the HEAs can bedivided into two regions; low-velocity (v < 1 m/s) and high-velocity region (v > 1 m/s). In the low-velocity region, the increasing
trend of the stress is clearly much stronger than that in the high-velocity region. The displacements of each atom within a crystalline region with 1 nm thick after being traversed by amoving GB are shown in the bottom right figure. We find
Shear strain
that the atoms in pure Cu are displaced by the GB as
Grain boundary
well as the ones in the HEAs. However, through calculatz
ing the mean displacement of each element, we also findxy
GB migrationthat no atom drag occurs in pure Cu, while Cu in the250
HEA
HEAs tends to be dragged by the moving GB over a long
Pure Cu
HEA
Pure Cu
200
distance. The velocity region in which Cu is strongly
Initial configuration
Initial configuration
1 nm
1 nm
dragged (< 1m/s) is coincidence to that in which the150
applied shear stress required for GB migration sharply
Fe Ni Cr Co Cu
Cu
100
increases. Importantly, we also confirm that Cu is themost segregable element to both stationary and moving
50
GBs in the HEAs and the trend is stronger with a0036
9 12 15decrease in GB velocity. Therefore, the segregated and
45!6+789:/;!0<=.3GBvelocity, v (m/s)
dragged atoms (that is Cu in this study) may make GB
migration difficult in the HEAs.
v = 0.07 m/s)*+,-!./-+..!012,3

Shear stress, τxy (MPa)v = 0.07 m/s

Final
GB position

Final
Initial
GB position GB position

Initial
GB position[1] K. Shiotani, T. Niiyama, and T. Shimokawa, “Dislocation Emission from Grain Boundaries in High-Entropy Alloys: Influence of Atomic Composition atGrain Boundaries”, Materials Transactions, 61 (2020), 1272-1279.

Contact information:
Kohei Shiotani, doctoral course student
Division of Mechanical Science and Engineering,
Graduate School of Natural Science and Technology, Kanazawa University
Kakuma-machi, Kanazawa, Ishikawa 920-1192, JAPANE-mail : k.shiotani@stu.kanazawa-u.ac.jp◆Our interest is to investigate the role of grain boundaries in excellent mechanicalproperties in high-entropy alloys. As one of the probable strengthening mechanisms
relevant to grain boundaries, we reported the effect of grain boundary segregation
on dislocation emission from grain boundaries in high-entropy alloys [1]. We now
focus on how the atomic-scale characteristics of high-entropy alloys, e.g., atomic
size difference and compositional heterogeneity of constitutional elements, have an
impact on grain boundary migration behavior.

High Entropy Alloys Introduction to Publicly Offered Research Teams

2022 MAY

AWARD
Haruyuki Inui, June 2021, THERMEC’ 2021 Distinguished Award, THERMEC’ 2021, Vienna, Austria.
Kodai Niitsu, Makoto Asakura, Koretaka Yuge and Haruyuki Inui, September 2021, The 1st Best Paper Award for Budding Author, The
Japan Institute of Metals and Materials, Japan.
Shuhei Yoshida, Takuto Ikeuchi, Yu Bai and Nobuhiro Tsuji, September 2021, The 1st Best Paper Award for Budding Author, The Japan
Institute of Metals and Materials, Japan.
Kaveh Edalati, September 2021, A Highly Cited Author of Materials Transactions, Japan.
Nobuhiro Tsuji, November 2021, 70th Anniversary Distinguished Achievement Award, The Japan Institute of Light Metals, Japan.
Takeshi Nagase, Mitsuharu Todai and Takayoshi Nakano, September 2021, The 69th Best Paper Award, The Japan Institute of Metals
and Materials, Japan.
Haruyuki Inui, November 2021, Humboldt Research Award, Alexander von Humboldt Foundation, Germany.
Takeshi Fujita, November 2021, Highly cited researcher 2021, Clarivate Analytics Co.,Ltd.
Saeid Akrami, Parisa Edalati, Masayoshi Fuji and Kaveh Edalati, January 2022, Top 3 Highly Read Manuscript of Materials Science andEngineering: R, Elsevier.
Shuhei Yoshida, February 2022, Inoue Research Award for Young Scientists, Inoue Foundation for Science, Japan.
Akihiko Chiba, March 2022, The 28th Masumoto Hakaru Award, The Japan Institute of Metals and Materials, Japan.
Akihiko Chiba, March 2022, The 61st Tanikawa-Harris Award, The Japan Institute of Metals and Materials, Japan.
Nobuhiro Tsuji, March 2022, The 61st Tanikawa-Harris Award, The Japan Institute of Metals and Materials, Japan.
Takeshi Wada, March 2022, The 80th Meritorious Award, The Japan Institute of Metals and Materials, Japan.
Masanori Enoki, Yohei Ohsawa and Horoshi Ohtani, March 2022, The Best Paper Award (Tawara Award), The Iron and Steel Institute ofJapan.
Katsunari Oikawa, March 2022, Ferrum Contribution Award, The Iron and Steel Institute of Japan.

PRESS
1
2
3
4
5

Press Release, 23 June 2021, “Decoupling between calorimetric and dynamical glass transitions in high-entropy metallic glasses”, J.
Jiang, Z. Lu, J. Shen, T. Wada, H. Kato, M. Chen, Nikkei Inc. URL: https://www.nikkei.com/article/DGXLRSP613072_T20C21A6000000/
Nature Index 2021 Materials Science, Nature Research., “Improving the mix for better control of nanocomposites”, H. Muto.
URL: https://www.nature.com/articles/d42473-021-00151-1
Press Release, 20 August 2021, “Nanoporous ultra-high-entropy alloys containing fourteen elements for water splitting electrocatalysis”,
Takeshi Fujita. URL: https://www.jst.go.jp/pr/announce/20210820/index.html.
Kyoto University HP: Latest research news, 31 August 2021, “Direct observation of local chemical ordering in a few nanometer range in
CoCrNi medium-entropy alloy by atom probe tomography and its impact on mechanical properties”, K. Inoue, S. Yoshida, N. Tsuji. URL:
https://www.kyoto-u.ac.jp/ja/research-news/2021-08-30-1
The Science News (No. 3843), 1st October 2021, “Direct observation of local chemical ordering in a few nanometer range inmedium-entropy alloy”, K. Inoue, S. Yoshida, N. Tsuji.

LATEST INFORMATIONInternational Meeting
High-Entropy Materials II-From Fundamentals to Potential Applications (MRS 2022 Spring Meeting), May 8-13, 2022, Honolulu, HI, USA(Hybrid). https://www.mrs.org/meetings-events/spring-meetings-exhibits/2022-mrs-spring-meeting
Symposium “High Entropy Alloys: Potential for industrial applications”, May 12, 2022 | Dresden & Online (Hybrid Event).
https://www.iws.fraunhofer.de/en/events/hea-symposium.html

Domestic Meeting
The Japan Institute of Metals (JIM) Symposium “Materials Science of High-Entropy Alloys”, March 15-17, 2022, Online meeting, Japan.
https://jim.or.jp/MEETINGS/me_index.html
2022 Startup Meeting of All Research Groups, May 17-18, 2022, Online meeting, Japan. https://highentropy.mtl.kyoto-u.ac.jp/members
The Japan Institute of Metals (JIM) Symposium “Materials Science of High-Entropy Alloys”, September 21-23, 2022, Fukuoka Instituteof Technology, Japan. https://jim.or.jp/MEETINGS/me_index.html
2023 Final Meeting of All Research Groups, March, 2023, Japan. https://highentropy.mtl.kyoto-u.ac.jp/members
The Japan Institute of Metals (JIM) Symposium “Materials Science of High-Entropy Alloys”, March, 2023, Tokyo City University, Japan.
https://jim.or.jp/MEETINGS/me_index.html

High Entropy Alloys
Science of New Class of Materials Based on
Elemental Multiplicity and Heterogeneity

CONTACTHEA Secretariat: In the Inui Research Group, Department ofMaterials Science and Engineering, Kyoto University
Yoshida Honmachi, Sakyo-ku, Kyoto, 606-8501, Japan
Tel: +81-75-753-5481, E-mail: hea-office@mtl.kyoto-u.ac.jp