MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
ISSN-L : 1345-9678
Current Trends in Research
Best Papers Awarded for Young Scientists by JILM and JIMM in Materials Transactions
Zenji Horita
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Keywords: Verband der Automobilindustrie, nanocluster, dislocation density, pore, hydrogen embrittlement, thermal conductivity, conversion treatment, multimodal microstructure, crystalline polymer, iridium
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2025 Volume 66 Issue 9 Pages 1272-1285

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Abstract

The ten best papers for young scientists were awarded by The Japan Institute of Light Metals (JILM) and The Japan Institute of Metals and Materials (JIMM) in Materials Transactions. Here, the awarded papers are briefly summarized as current trends in research of Materials Transactions. Among the ten best papers, six were from JILM for young scientists whose ages are 30 or below and four from JIMM for those with ages of 35 or below. A total of six best papers were originally published in Japanese in Journal of the Japan Institute of Light Metals and Journal of The Japan Institute of Metals and Materials as cutting-edge research in JILM and JIMM. In association with all the awarded papers, special issues edited in Materials Transactions are also briefly introduced to show the recent activities of Materials Transactions.

1. Introduction

As current trends in research of Materials Transactions, it is our great pleasure to introduce the young scientists best papers [1–10] which were awarded in 2023 and 2024 by The Japan Institute of Light Metals (JILM) and The Japan Institute of Metals and Materials (JIMM). The best papers include a total of ten where six papers are from JILM [1–6] and four papers from JIMM [7–10]. The JILM and JIMM are two companion institutes among 14 institutes and societies sharing publication from Materials Transactions [https://jimm.jp/en/publications/journal.html]. Authors may chose either one of the 14 institutes and societies depending on the specialties in terms of materials, analytical procedures and processing technologies, although some institutes and societies accept the submission only from members including expected members. Since 2020, Materials Transactions has made a series of announcements for the best paper awards [11–15].

The selection of the best papers in JILM [1–6] was made in two-step processes: first through a recommendation committee and second through an evaluation committee. The members in the recommendation committee nominates around ten papers out of all the papers published through JILM in the past one year. Members of the evaluation committee then score the whole nominated papers, and the three papers which earned the highest scores are awarded as Light Metal Paper Prize. If the first author is at the age of 30 or less, the corresponding paper wins the award as Light Metal Paper-by-Newcomer Prize (Young Scientists Best Paper). Scoring for the best papers in JILM is made based on the following criterions: (a) sufficient originality, (b) high potential for significant research advancement, (c) solving long-term problem, (d) being far ahead of others and (e) enormous contribution to application development.

For the young scientists best papers in JIMM, the selection committees carefully evaluated the papers of which authors are at the age of 35 or less. Recommendation of the papers is made by referees of reviewing processes, editorial members of Materials Transactions and board members of the Japan Institute of Metals and Materials including authors’ self-recommendation. Each paper was rigorously scored by about 10 members of the award selection committee representing either of the following six research areas: (1) materials physics, (2) microstructures of materials, (3) mechanics of materials, (4) materials chemistry, (5) materials processing, and (6) engineering materials and their applications. The evaluation criteria in JIMM are based on (a) sufficient originality and novelty and (b) good potential for significant research advancement.

It is noted that five of the young scientist best papers in JILM [2–6] and one of the young scientist best papers in JIMM [10] were originally published in Japanese in Journal of The Japan Institute of Light Metals [16–20] and in Journal of The Japan Institute of Metals and Materials [21], respectively. They were translated to English following the rule of Materials Transactions. Here, the ten best papers for young scientists are introduced below [1–10, 16–21] with brief summaries provided by the corresponding authors.

2. (JILM Young Scientist Best Paper Award) “Influence of Initial Extruded Microstructures of Al-4.4Zn-1.4Mg Alloy Flat Bar on VDA Bendability” by Amalina Aina Kaharudin, Ran Saeki, Mai Takaya, Tadashi Minoda, Tomoyuki Homma (Vol. 64, No. 2 (2023) pp. 421–428) [1]

The bendability of extruded Al-4.4Zn-1.4Mg (mass%) alloy flat bars with a cross section of 70 mm width and 1.4 mm thickness, having two types of microstructures, which are fibrous and recrystallized, is evaluated by a Verband der Automobilindustrie (VDA) bending test without pre-strain [22]. The recrystallized specimen has a larger bending angle until a 30 N load drop (α–30N) from the maximum load during the VDA bending deformation [23]. The recrystallized microstructure shows a strong Cube texture in the inner microstructure, while the crystal orientation distributions of the fibrous microstructure {322}⟨230⟩ to {212}⟨021⟩ and {211}⟨131⟩ to Goss are predominant in the initial state. A finite element analysis confirms that the tensile side of both specimens experiences a high maximum shear stress at a depth of approximately 300–500 µm from the outermost surface. At a maximum load bending angle (αFmax), the pole figure of the fibrous microstructure shows the assemblage of crystal orientations towards Brass {110}⟨112⟩, as shown in Fig. 1 [24]. This could be the cause of a faster 30 N load drop, as the Brass orientation contributes to a faster shear bands formation [25]. In addition, the fibrous microstructure has a higher volume fraction of second phase particles than the recrystallized microstructure, leading to a larger area fraction of microvoids at αFmax. During bending deformation, the shear bands tend to accumulate at localized shear strain areas, resulting in a crack approximately 300 µm long at the tensile side of the fibrous microstructure at α–30N. Despite having a larger α–30N, the recrystallized microstructure only shows a small crack in the coarse grains because the shear bands are evenly distributed within a 300 µm depth range from the outermost surface (Fig. 1). The accumulation of shear bands in both microstructures up to 300 µm from the outermost surface of the tensile side indicates that texture control and microvoid suppression are crucial in this region to enhance VDA bendability.

Fig. 1

Band contrast and local misorientation images, inverse pole figure maps and (100) pole figures of both samples at αFmax and tensile sides (region A). ND and TD indicate the extrudate normal and transverse directions, respectively. The observations were conducted on the ND-TD plane, which is parallel to the VDA bending punch load direction. (online color)

3. (JILM Young Scientist Best Paper Award) “Effects of Local Bonding between Solute Atoms and Vacancy on Formation of Nanoclusters in Al–Mg–Si Alloys” by Kensuke Kurihara, Ivan Lobzenko, Tomohito Tsuru, Ai Serizawa (Vol. 64, No. 8, (2023), pp. 1930–1936) [2]

In Al-Mg-Si alloys, two types of solute-atom clusters (nanoclusters), Cluster (1) and Cluster (2), are formed depending on the formation temperature. It is thought that Cluster (1) formed at near room temperature is less likely to transition to the strengthening phase, in contrast, Cluster (2) formed at near 100°C is more likely to transition to the strengthening phase [26]. To clarify such complicated behavior of nanocluster formation, various research has been conducted including TEM observations [27] soft X-ray XAFS analysis [28, 29], positron annihilation spectroscopy [30] and computer simulations [31, 32]. The thermal stability of nanoclusters is presumed to be significantly affected by the local structure because nanoclusters do not have a specific long-range structure, unlike metastable phases. Thus, it is essential to clarify the effect of local bonding to discuss the thermal stability of nanoclusters, which are mainly composed of solute atoms. In the present study, first-principles calculations were carried out to evaluate the two- and three-body interactions between Mg, Si atoms and vacancies in the Al matrix and estimate the effect of local bonding on the formation of nanoclusters. Monte Carlo simulations were subsequently performed to investigate the stable structure of the nanocluster formed in Al-Mg-Si alloys. The main findings are that the Mg–Si and Si–Vac pairs are stable in the Al matrix. The result shows that the solute atoms easily aggregate with different types of solute atoms and that the Si atom has a strong attractive interaction with a vacancy. Furthermore, Mg–Si–vacancy triplets are more stable than Mg–Si and Si–vacancy pairs in the Al matrix (Fig. 2). In addition, the nanoclusters in the Al matrix were thermally stabilized by the stable configurations between solute atoms and vacancy. Finally, the first-principles calculations suggested that the local bondings within a nanocluster play a significant role in not only the thermal stability but also the formation and growth behavior of nanoclusters during aging at low temperatures.

Fig. 2

Binding energies of triplet composed of two solute atoms (Mg, Si) and a vacancy in the Al matrix. (a) (Mg, Vac) and (Si, Vac) and (b) Mg, Si and Vac.

4. (JILM Young Scientist Best Paper Award) “Effect of Precipitation Size on Dislocation Density Change during Tensile Deformation in Al-Zn-Mg Alloy” by Masahiro Hirata, Koichi Iwata, Daisuke Okai and Hiroki Adachi (Vol. 64, No. 11 (2023), pp. 2584–2590) [3]

The effect of changing the precipitate radius from 0 to 6 nm on the flow stress and dislocation density during tensile deformation in the Al–Zn–Mg precipitation-hardening alloy was investigated. The dislocation densities during tensile deformation were measured using in-situ X-ray diffraction with a time resolution of about 2 s at the SPring-8 synchrotron radiation facility [33, 34], and the precipitate sizes were measured using small-angle X-ray scattering measurements [35]. In region III, which is the plastic deformation region, the increase in dislocation density with deformation was largest under the peak aging condition. However, as shown in Fig. 3, the amount of work hardening was small, and the contribution of work hardening was minimal. On the other hand, under under-aging and over-aging conditions, the increase in dislocation density in region III was smaller than in the peak aging condition, but the amount of work hardening was larger than in the peak aging condition. This revealed that the amount of work hardening is not determined solely by the amount of dislocation multiplication, but varies depending on the amount and strength of obstacles that provide stronger resistance to the movement of mobile dislocations than forest dislocations. This result shows that the flow stress in precipitation hardening alloys cannot be expressed as a simple sum of the amounts of precipitation hardening and dislocation hardening.

Fig. 3

Aging time dependency of the slope, k of the Bailey-Hirsch relationship (stress vs. the square root of dislocation density) in Al-Zn-Mg alloys during the plastic deformation region (dislocation change region, stage III).

5. (JILM Young Scientist Best Paper Award) “Growth Behavior of Pores and Hydrogen Desorption Behavior in Pure Aluminum and A6061 Aluminum Alloys” by Shono Yaegashi, Kazuyuki Shimizu, Yasuhiro Kamada, Hiroyuki Toda, Hiro Fujihara, Masayuki Uesugi, Akihisa Takeuchi (Vol. 65, No. 1 (2024) pp. 85–92) [4]

An increase in the volume fraction of pores in aluminum alloys causes a decrease in the elongation and the strength of alloys [36–38]. To improve the mechanical properties of aluminum alloys, it is important to understand the growth and shrinkage behavior of pores [39, 40]. In this study, we analyzed the relationship between hydrogen desorption behavior and the growth/shrinking behavior of pores in A6061 alloys and pure aluminum using thermal desorption analysis and synchrotron radiation X-ray tomography [41]. In pure aluminum, the fine pores began to annihilate at temperatures above 500°C and the relatively large pores coarsened. In contrast, the pores shrank with increasing temperature in A6061 alloy.

The influence of second-phase particles has been discussed as a possible explanation for the difference in the nature of pores at elevated temperatures in pure aluminum and A6061 alloys. Figure 4 shows a schematic illustration of the differences in hydrogen desorption and the related growth behavior of pores in pure aluminum and A6061 alloys. In pure aluminum without second-phase particles, most of the hydrogen desorbed from the pores is hindered by the passive film and cannot be released. As a result, the hydrogen concentration in the matrix becomes relatively high, making it difficult for hydrogen within the pores to desorb. This leads to an increase in the internal pressure of the pores, causing them to grow. As in the A6061 alloy, much of the hydrogen desorbed from the pores due to heating is released externally from the second-phase particles on the aluminum surface, resulting in pore shrinkage due to the internal pressure drop of pores.

Fig. 4

Schematic illustration of differences in hydrogen desorption and the related growth behavior of pores in (a) pure aluminum and (b) A6061 alloys, which attributed to the presence or absence of second-phase particles. (online color)

6. (JILM Young Scientist Best Paper Award) “Multi-Modal 3D Image-Based Simulation of Hydrogen Embrittlement Crack Initiation in Al-Zn-Mg Alloy” by Ryota Higa, Hiro Fujihara, Hiroyuki Toda, Masakazu Kobayashi, Kenichi Ebihara, Akihisa Takeuchi (Vol. 65, No. 8 (2024) pp. 899–906) [5]

In Al-Zn-Mg alloy, it is indispensable to suppress hydrogen embrittlement (HE) for developing a high-strength alloy. In particular, we need to understand the initiation of intergranular fracture (IGF) because it is the main mode of HE fracture. In a previous study, it was reported that spontaneous debonding of GB occurs due to hydrogen accumulation [42]. Moreover, hydrogen accumulation is caused by stress localization in deformed polycrystalline metals [43]. It is necessary to evaluate hydrogen accumulation behavior at GBs to understand the initiation behavior of IGF.

In the present study, we investigated the distribution of stress and hydrogen concentration in actual fractured regions by simulation employing a crystal plasticity finite element method and hydrogen diffusion analysis in a 3D image-based model, which was created based on 3D polycrystalline microstructure data obtained from X-ray imaging technique. Combining the simulation and in-situ observation of fracture behavior using X-ray CT (Fig. 5), the conditions for intergranular crack initiation were discussed. As a result, no clear relationship was found between the hydrogen concentration and crack initiation behavior. It is considered that this is because the influence of hydrogen trapping in precipitates [44] at GBs and penetration of external hydrogen [45] on crack initiation were not considered. In addition, it was found that GBs with higher stress normal to GB tended to be more prone to crack initiation. The stress normal to GB, which is increased by crystal plasticity, is considered to be the dominant mechanical factor in crack initiation. From these considerations, we infer that the strength of the GB-precipitate interface is reduced by hydrogen enrichment due to diffusion of internal hydrogen and penetration of external hydrogen, and that the initiation of intergranular cracks is caused by the high stress normal to GB because of crystal plasticity.

Fig. 5

(a) Image of crack 4 in the region C at εappl = 3.2% and distribution of (b) hydrostatic stress and (c) hydrogen concentration at slice DD′ around the GB where crack 4 initiated at εappl = 0.97%. GB 1 (white line) is the GB where crack 4 occurred. (online color)

7. (JILM Young Scientist Best Paper Award) “Mg-1.88Zn-0.75Y Cast Alloys with High Thermal Conductivity of 141 Wm−1K−1” by Yunsheng Wang, Shin-ichi Inoue and Yoshihito Kawamura (Vol. 65, No. 10 (2024) pp. 1358–1366) [6]

The present study focuses on the Mg-Zn-Y alloys, in which the mixing enthalpy of the added element pair is negatively large (ΔHmix = −31 kJ/mol) and can exhibit great mechanical strength due to the LPSO phase (Mg12ZnY) [46–50], W phase (Mg3Zn3Y2) [51, 52], or I phase (Mg3Zn6Y) [53, 54]. By optimizing the alloy composition and heat-treatment conditions, a Mg-Zn-Y alloy with high thermal conductivity of 141 Wm−1K−1 that is equivalent to approximately 90% of the thermal conductivity of pure Mg was developed.

The optimal alloy composition was Mg-1.88Zn-0.75Y (at%), in which the ratio of Zn content to Y content was 2.5 and the Y content was 0.75 at%. The alloy was composed of α-Mg + W phase + I phase. Heat treatment under the optimal heat treatment conditions, where temperature, time and cooling rate were 633 K, 15 h and air cooling, respectively, improved the thermal conductivity by 27 Wm−1K−1 from 114 to 141 Wm−1K−1 (Fig. 6). Fine W phase precipitation in α-Mg matrix by the heat-treatment caused a reduction of solute Y and Zn elements in α-Mg matrix, resulting in improvement of the thermal conductivity.

Fig. 6

Effect of (a) heat treatment temperature and (b) heat treatment time on thermal conductivity in heat-treated Mg-1.88Zn-0.75Y alloys, where cooling rate was air cooling.

The high thermal conductivity of the Mg-1.88Zn-0.75Y ternary alloy developed in this study is the same as the high thermal conductivity of a Mg-5.0Al-3.0Ca alloy [55, 56], in both cases, compounds composed of added elements are precipitated from the α-Mg matrix through heat treatment, resulting in a significant increase in thermal conductivity. These results revealed that adding element pairs with negatively large mixing enthalpy is important for improving the thermal conductivity by heat treatment. Therefore, it can be considered that adding element pairs with negatively large mixing enthalpy will become a new material design guideline in developing Mg alloys with high thermal conductivity.

8. (JIMM Young Scientist Best Paper Award) “Chemical Conversion Treatment of AA5083 Aluminum Alloy and AISI 1045 Carbon Steel under Galvanically Coupled Condition in Na2MoO4: Effect of pH on Corrosion Resistance” by Takumi Kosaba, Izumi Muto, Masashi Nishimoto and Yu Sugawara (Vol. 64, No. 2 (2023) pp. 568–577) [7]

For multi-material structures with Al alloy/steel joints, the localized degradation of Al alloys due to galvanic corrosion is one of the serious problems [57–60]. To enhance galvanic corrosion resistance, optimal conditions of chemical conversion treatments for Al alloys have been proposed [61–65]. In terms of the occurrence of localized corrosion on Al alloys, it has been reported that the degradation is initiated at the interface between alloy-matrix and Fe- or Cu-containing intermetallic particles owing to higher cathodic reactivity on these particles [66–68]. However, there is no literature of optimal conditions for Al alloy/steel joints in chemical conversion treatment based on the local electrochemistry around the harmful particles. In this study, to analyze the effect of solution pH of Na2MoO4 chemical conversion treatment for Al alloy/steel joints on corrosion resistance, AA5083 aluminum alloy and AISI 1045 carbon steel were therefore immersed in 50 mM Na2MoO4 at pH ranges of 8–12 under galvanically coupled condition [7]. The galvanic corrosion resistance of the AA5083 alloy connected to the AISI 1045 carbon steel was assessed afterwards, immersing in diluted synthetic seawater. Figure 7 shows the number of localized corrosion damages observed in an electrode area of 10 mm × 10 mm. AA5083 treated at pH 11 was found to be the better corrosion resistance. The oxygen reduction reactivity of bulk Al6(Fe, Mn) suppressed with increasing solution pH of the conversion treatment. The Al6(Fe, Mn) particles on AA5083 became no preferential cathodes, and alkalization through oxygen reduction would not occur when the treatment was proposed above pH 9. Auger electron spectroscopy analysis demonstrated that Mo-accumulation, Fe-removal, and film thickening on the particles of AA5083 treated at pH 11. The suppression of the cathodic reactivity on the Al6(Fe, Mn) particles is attributed to the surface modification, resulting in the improved galvanic corrosion resistance of AA5083.

Fig. 7

Effect of solution pH used in the conversion treatment on the number of localized corrosion damages on as-polished and conversion-treated AA5083 after galvanic current and potential measurements.

9. (JIMM Young Scientist Best Paper Award) “Relationship between Cluster-Arranged Nanoplate Formation and Mechanical Properties of Dilute MgYZn Alloys Prepared by Combination of Low-Cooling-Rate Solidification and Extrusion Techniques” by Seitaro Ishizaki, Michiaki Yamasaki, Koji Hagihara, Soya Nishimoto, Taisuke Nakamura and Yoshihito Kawamura (Vol. 64, No. 4 (2023) pp. 756–765) [8]

High-strength and dilute Mg–Y–Zn alloys with cluster-arranged layer/nanoplate (CAL/CANaP) precipitates were developed via combined processes of low-cooling-rate solidification and extrusion techniques [8, 69]. A slow-cooling solidification process with cooling rates ranging from 0.1 to 0.01 K·s−1 produces a “CAL-aggregated region” in which L12-type Y8Zn6 clusters [70–72] are ordered on the basal planes of the α-Mg matrix of the Mg99.2Y0.6Zn0.2 (at%) alloy. The CAL-aggregated region is composed of solo-CAL and CANaP precipitates. As the cooling rate decreased, the area fraction of the CAL-aggregated region increased, and the CANaP in the center grew into a blocky LPSO phase. The enlargement of the CAL-aggregated region increased the CAL/CANaP spacing.

The multimodal microstructure of the extruded Mg99.2Y0.6Zn0.2 alloys prepared from low cooling rate-solidified ingots consisted of three characteristic regions: (i) dynamically recrystallized (DRXed) fine α-Mg grains, (ii) worked coarse α-Mg grains with a CAL-aggregated region, and (iii) worked blocky LPSO grains [73]. The strength and ductility of the extruded Mg–Y–Zn alloys may be controlled by the volume fractions of the worked α-Mg/LPSO and DRXed α-Mg grains, respectively [74]. Figure 8 shows that the area fraction of the worked α-Mg grains region and the kink-boundary dispersion play an essential role in increasing the strength. These two factors may be regulated by the CANaP spacing and area fraction of the CAL-aggregated region; it is desirable to control the CANaP thickness and spacing to approximately 1 µm and ≤0.8 µm, respectively, to form the worked grains in which kink bands are introduced [75–82].

Fig. 8

(a) Relationship between the tensile properties and area fraction of worked α-Mg grain region and (b) relationship between the tensile properties and kink-boundary dispersion in worked α-Mg grains of extruded Mg99.2Y0.6Zn0.2 alloys. (online color)

This study demonstrated that multimodal microstructure control is possible even in diluted Mg–Y–Zn alloys without an LPSO phase and that high strength can be achieved by retaining a moderate amount of worked grains with kink boundaries.

10. (JIMM Young Scientist Best Paper Award) “Effects of High-Pressure Press on the Tensile Properties and Morphology of Polypropylene” by Yukino Ito, Shotaro Nishitsuji, Hironari Sano, Masaru Ishikawa, Takashi Inoue and Hiroshi Ito (Vol. 64, No. 4 (2023) pp. 774–779) [9]

In the field of metals, especially in magnesium alloys, a new concept has been reported that introducing a kink by applying compression or other deformation to a material with an LPSO structure [48, 50, 75] in which hard and soft layers are alternately stacked, results in higher strength. Because crystalline polymers are alternately layered with a crystalline phase, the hard layer, and an amorphous phase, the soft layer, it is expected that crystalline polymers can be made stronger if kinks can be introduced by applying compression or other deformation. In this study, the effects of a high-pressure press on the tensile properties and morphology of polypropylene (PP) were investigated. Figure 9 shows that stress as a function of strain for as-mold PP and PP after applying different amounts of pressure. We found that a high-pressure press reduced the strain at break but increased the tensile modulus and the stress at break in the stress–strain curves. Thus, we succeeded in developing high-strength PP using a high-pressure press. In addition, it is found that the tensile properties were isotropic with no directional dependence after press. This implies that the tensile strength can be increased isotropically. Observing the morphology parallel to the press direction by small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS), it was found that the crystal lamellae spread isotropically. Conversely, observation of the morphology perpendicular to the press direction by optical microscopy (OM) and transmission electron microscopy (TEM) revealed the formation of a shear band where deformation was concentrated owing to pressure. In the shear band, it was found that lamella fragmentation occurred and a kinked structure was formed. In this region, the molecular chains may be constrained by pressure, and become a tension state, which leads to the improvement of the mechanical properties.

Fig. 9

Stress as a function of strain for as-mold PP and PP after applying different amounts of pressure. (online color)

11. (JIMM Young Scientist Best Paper Award) “Volatile Separation and Recovery of Iridium from Oxygen Evolution Electrodes Using Calcium Oxide” by Kosuke Takahashi, Ryoji Sanekata and Takashi Nagai (Vol. 65, No. 1 (2024), pp. 71–75) [10]

Iridium is a platinum-group metal with unique catalytic properties and chemical stability. Because of these characteristics, the metal is used in the form of iridium–tantalum oxides in the catalytic layer of oxygen evolution electrodes [83, 84]. Recovering Ir from end-of-life products is important because of its low production volume, the uneven geographical distribution of Ir sources, and high supply risks. However, Ir recovery requires its dissolution in aqueous solution using strong acid, making the procedure not only dangerous but also hazardous to the environment [85]. In addition, the dissolution of metals other than Ir in aqueous solution causes a decrease in recovery and purity in separation and refinement. Therefore, the solubility of the acid must be improved while separating only Ir before dissolution [86].

Accordingly, we developed a method to extract only Ir from the catalyst layer of oxygen evolution electrodes and, simultaneously, recover Ir as a Ca–Ir composite oxide that is soluble in hydrochloric acid. Only iridium oxide was volatilized from the catalyst layer of the oxygen evolution electrode at 1373 K in air and contacted with CaO via the gas phase to obtain an Ca-Ir composite oxide (Fig. 10). The composite oxide obtained was dissolved in hydrochloric acid and subsequently analyzed. As a result, the composite oxide was easily dissolved in hydrochloric acid and exhibited a high Ir dissolution rate. In addition, no dissolution of Ta was observed and only Ir could be separated and recovered. This method is useful in terms of efficiency, safety, and cost because only Ir can be recovered from spent electrodes using CaO without using strong acid. Further, Ir is recovered via gas phase, and it is expected that it could be recovered from products other than oxygen evolution electrodes at the same time [10, 21].

Fig. 10

(left) Simulated and (right) CaO-side samples (a) before and (b) after heating at 1373 K.

12. Editor’s Remarks

JILM is an active companion of Materials Transactions to publish papers related to light metals such as Al, Mg and Ti including their alloys. Submission requires authors to be a member of JILM. Articles of 25–30 per year are published through JILM, which come to about 5% of the total in Materials Transactions. In 2022, a special issue entitled “Aluminium and its Alloys for Zero Carbon Society” was edited by JILM [87], collecting one overview paper [88], two review papers [89, 90] and 24 regular papers [91–114], and published in February, 2023. They were selected with strict review processes among the presentations made in “The 18th International Conference on Aluminium Alloys (ICAA 18)”, held in Toyama, Japan on September 4–8, 2022. In addition, JILM has published comprehensive review papers [115–119] within the last two years, which are listed as follows.

  1. (1)    “Grain Refinement of Cast Aluminum by Heterogeneous Nucleation Site Particles with High Lattice Matching” by Watanabe et al. [115].
  2. (2)    “Materials Design for Improving Mechanical Properties of Ultra-Lightweight Mg-Li Based Alloys” by Mineta [116].
  3. (3)    “Severe Plastic Deformation of Light Metals (Magnesium, Aluminum and Titanium) and Alloys by High-Pressure Torsion: Review of Fundamentals and Mechanical/Functional Properties” by Edalati [117].
  4. (4)    “Etching Behavior and Dielectric Film Formation on Aluminum Foil Stocks for Electrolytic Capacitors: A Review” by Osawa [118].
  5. (5)    “Deformation Behavior of Aluminum Alloys under Various Stress States: Material Modeling and Testing” by Kuwabara and Barlat [119].

Regarding the 6 awarded papers from JILM, the article by Wang et al. [6] is concerned with Mg-Zn-Y alloys, where thermal conductivities were maximized by controlling the microstructures. It should be noted that, because the thermal properties are important in metallic materials, Materials Transactions published several articles on this topic [120–128]. The rest of the awarded papers are all for Al alloys, where three papers dealt with Al-Zn-Mg alloys and the other two papers with Al-Mg-Si alloys. The Al-Zn-Mg alloys are well known as typical high-strength alloys. The effect of precipitate sizes on dislocation density was investigated by Hirata et al. using an in situ tensile facility in SPring 8 [3]. Crack initiation leading to hydrogen embrittlement was examined by Higa et al. using a 3D facility in SPring 8 [5]. The bendability of Al-Zn-Mn alloys was investigated by Kaharudin et al. from the comparison between a fibrous state and a recrystallized state [1]. The rest of the two studies on the Al-Mg-Si alloys are for nanocluster formation by Kurihara et al. [2] and for hydrogen desorption behavior by Yaegashi et al. [4], both of which significantly affect the strength and ductility of the alloys.

JIMM coordinates the publication system of Materials Transactions for the 14 institutes and societies. It accepts papers with various types of materials including ceramics, semiconductors and polymers as well as metals and alloys as referred to the submission website of Materials Transactions [https://jimm.jp/en/publications/category.html]. The awarded paper by Takahashi et al. dealt with the recovery of Ir which is a rare metal with extremely high cost [10]. In the paper by Ito et al. [9], polypropylene, which is a crystalline polymer, was strengthened for the first time by the formation of kinks after deformation by compression. The two other awarded papers are concerned with Mg-Y-Zn alloys by Ishizaki et al. [8] to enhance the strength and ductility through cluster arranged nanoparticles, and with chemical conversion treatment of Al/steel joints by Kosaba et al. [7] to improve galvanic corrosion resistance of an A5083 alloy. It should be noted that the papers by Ito et al. [9] and Ishizaki et al. [8], were published in a special issue of “Kink-Strengthening of Mille-Feuille Structured Materials” [129] together with other 14 papers [130–143]. In addition, JIMM published a special issue called “Materials Science on High-Entropy Alloys II” [144] and this is in fact the second special issue followed by the first issue entitled “Materials Science on High-Entropy Alloys” [145]. Because the first special issue gained much attention, the second special issue was edited with the total of ten papers [146–155] and published in August 2024 [144]. It should be noted that both special issues were edited so as to introduce outcome of the national research projects from 2018 to 2022 supported by Grant-in-Aid for Scientific Research on Innovative Areas, MEXT Japan.

Apart from such special issues, two more special issues were published in Materials Transactions: one of them is entitled “Superfunctional Nanomaterials by Severe Plastic Deformation” [156] including 33 overview papers [125, 157–188], 16 review papers [189–204], four regular articles [205–208] and one rapid publication [209]. Readers may also find comprehensive summaries for this special issue [210, 211]. The other special issue is entitled “Development and Functionality of Titanium and Its Alloys as Structural, Biocompatible, and Energy Materials” [212], which appeared in May 2025 including one review paper [213] and 19 regular articles [214–232] and this was edited by collaboration between members of JIMM and the Indian Institute of Metals (IIM).

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