Search Results (15)

GH4099 is a nickel-based, high-temperature, precipitation-strengthened alloy with excellent mechanical properties and corrosion resistance, widely used in aerospace components. The performance of parts produced by additive manufacturing depends significantly on alloy powder quality and heat treatment. In this study, GH4099 alloy powder was prepared using the EIGA method, and its morphology, particle size distribution, and flowability were analyzed. The mechanical properties and microstructure of parts before and after solution-aging treatment were compared. Results showed that the powder had good sphericity and flowability, with a median diameter D50 of 28.88 μm. The formed parts underwent solution treatment at 1140 °C for 2 h followed by aging at 850 °C for 8 h. After heat treatment, the transverse tensile strength increased to 1122.11 MPa (+15.1%) and the yield strength to 866.56 MPa (+22.3%), while the longitudinal tensile strength reached 1116.81 MPa (+29.4%) and the yield strength 831.61 MPa (+35.2%). This improvement is attributed to the precipitation of γ′ phase. Fractographic analysis revealed a mixed fracture mode characterized by ductile dimples and cleavage facets, indicating that the alloy exhibits favorable toughness-related features under mechanical loading. These findings demonstrate the excellent microstructure and mechanical performance of GH4099 alloy in AM applications, providing a basis for its further use in high-performance aerospace components. Full article

The main method for large-scaled preparing powder superalloys in the production process is inert gas atomization, particularly vacuum-induced gas atomization (VIGA). A novel technique called electrode-induced gas atomization (EIGA) with a crucible-free electrode was proposed to prepare non-inclusion superalloy powders. In this study, a Ni-based superalloy of FGH4096 powder was prepared using both the VIGA and EIGA methods, while blanks were prepared through direct hot isostatic pressing (as-HIPed) near-net-forming method. The particle size, morphology, microstructure, and mechanical properties of the powders and blanks were compared via a laser particle size analyzer, SEM, TEM, and room-temperature and 650 °C tensile tests. The results indicated that EIGA-prepared powders exhibited a finer particle size and better surface quality than the one prepared via VIGA, which showed reduced satellite powders. However, the as-HIPed blank of EIGA-prepared powders had a lower secondary γ’ ratio and slightly reduced strength compared to the as-HIPed blank of VIGA-prepared powders due to its slightly lower secondary γ’ phase ratio and less effective inhibition of dislocation movement. Furthermore, the overall performance of the two samples did not differ significantly due to the similar microstructural characteristics of the powders. However, the variation in particle size affects heat conduction during the HIP process, resulting in slight differences in blanks’ properties. Full article

The paper focuses on material characterization and technology properties of a new Ti-12Al-42Nb spherical powder alloy for additive manufacturing of personal medical implants. The electrode induction melting inert gas atomization (EIGA) method was used to produce the powder alloy. The powder sphericity coefficient (PSC) was 1.02. Image J software was used to calculate the spherical degree by processing images sets from scanning electron microscopy (SEM) and optical microscopy (OM). SEM of particles cross-sections indicated internal thermal-induced porosity (TIP) with a 2.3 μm pore diameter. Particle size distribution was in the range from 15.72 μm (d10) to 64.48 μm (d100) as measured by laser particle analyzer. It was indicated that flowability and powder bulk density were 196 sec and 2.79 g/cm³, respectively. XRD analysis confirmed the beta phase of the powder alloy with no additional phases. X-ray fluorescence spectrometry confirmed the alloyed composition. Reducing and oxidative melting methods of analysis showed a slight amount of impurities: oxygen (0.0087 wt.%), nitrogen (0.03 wt.%), hydrogen (0.0012 wt.%), sulfur (0.0016 wt.%), and carbon (0.022 wt.%). Simultaneous thermal analysis (STA) was performed to indicate weight growth and losses and thermal effects in argon, nitrogen, and air as well as the oxidation of Al₂O₃, TiO₂, and Nb₂O₅ on the surface layer of Ti-12Al-42Nb powder alloy particles. Different phase transformations of γAl₂O₃ $\to$ θAl₂O₃ $\to$ αAl₂O₃ and TiO₂ rutile $\to$ TiO₂ anatase phase transformation were detected by STA in the oxidative layer. Full article

After a decade of dormancy following the release of Tōhō Studios’ Godzilla: Final Wars (2004), Godzilla and other kaijū burst back onto the scene with Legendary Pictures’ Godzilla (2014). Several American sequels and a television series set in Legendary’s MonsterVerse quickly followed over the next ten years. Meanwhile, Japan’s Tōhō used their radioactive creation’s global success to reignite their own films with Shin Godzilla (2016), an animated trilogy, and Godzilla Minus One (2023). Short-format media like Chibi Godzilla and Godziban also circulated thanks to streaming services. Similarly, Godzilla’s longtime competitor Gamera also emerged from hibernation in an animated series produced by Kadokawa Corporation, Gamera Rebirth (2023). But how do these new installations relate to or depart from their predecessors’ predilection to address environmental concerns? This article continues the ecocritical analysis of kaijū eiga, expanding it to the 2010s and 2020s, as a coda to our duograph Japan’s Green Monsters (2018). This article picks up where we left off, examining the recent releases from an ecocritical standpoint. This analysis reveals that today’s films remain steeped in environmental commentary, but both fragmented and updated for the new concerns of the twenty-first century. Full article

Electrode induction melting gas atomization (EIGA) technology is a commonly used and effective method for producing spherical metal powders in additive manufacturing. In this paper, we aim to describe the atomization and fragmentation of liquid sheets from a typical swirl nozzle and highlight the primary breakup of titanium alloy powder production. We developed a computational fluid dynamics (CFD) approach to simulate the primary disintegration process of the molten metal using the volume of fluid (VOF) method coupled with the large eddy simulation turbulence model (LES). Our numerical results show that high-speed spraying creates supersonic airflow in the atomization chamber. Recirculation is the main area where primary atomization occurs. The formation of the recirculation zone is the direct driving force that allows atomization to proceed, which will increase turbulence intensity and achieve higher atomization efficiency. VOF-LES simulation can capture some qualitative results such as conical melt-sheet shape, wave formation, ligament formation, and perforation formation. The primary droplet size mainly ranges between 200 and 800 μm. Finally, with increasing gas pressure, the particle size of the atomized powder gradually decreases, and the particle size distribution becomes narrower. Full article

Electrode induction melting gas atomization (EIGA) is a wildly applied method for preparing ultra-clean and spherical metal powders, which is a completely crucible-free melting and atomization process. Based on several experiments, we found that although the sphericity of metal powders prepared by EIGA was higher than that of other atomization methods, there were still some satellite powders. To understand the formation mechanism of the satellite, a computational fluid dynamics (CFD) approach FLUENT and a discrete particle model (DPM) were developed to simulate the gas atomization process, and several EIGA experiments with different argon pressures (2.5–4.0 MPa) were designed. A numerical simulation of the gas-flow field verified the formation trajectory of satellites, and the Hall flow rate of the powder produced under different pressures was 13.3, 13.8, 15.6, and 16.8, which were consistent with the prediction of the numerical simulation. This study provides theoretical support for understanding the satellite formation mechanism and improving powder sphericity in the EIGA process. Full article

High-activity spherical TaNbTiZr refractory high-entropy alloy (REHA) powders were successfully prepared by electrode induction melting gas atomization (EIGA) and plasma rotating electrode process (PREP) methods. Both the EIGAed and PREPed TaNbTiZr RHEA powders have a single-phase body-centered cubic (BCC) structure and low oxygen content. Compared with the EIGAed powders, the PREPed powders exhibit higher sphericity and smoother surface, but larger particle size. The average particle sizes of the EIGAed and PREPed powders are 51.8 and 65.9 μm, respectively. In addition, both the coarse EIGAed and PREPed powders have dendritic structure, and the dendrite size of the EIGAed powders is larger than that of the PREPed powders. Theoretical calculation indicates that the cooling rate of the PREPed powders is one order of magnitude higher than that of the EIGAed powders during the solidification process, and the dendritic structure has more time to grow during EIGA, which is the main reason for the coarser dendrite size of the EIGAed powders. Full article

The quality and properties of metal powders are essential for powder metallurgical (PM) processes in general and for additive manufacturing (AM) processing routes in particular. Thus, a variety of atomization technologies were established meeting the multiple needs of the different processing technologies. However, the production of refractory metal alloy powder remains challenging due to their high liquidus temperatures (>2000 °C), the formation of brittle intermetallic phases, as well as the reactivity with and sensitivity to interstitials of the constituting elements. In this contribution, powders made of Mo-20Si-52.8-Ti (at.%) were produced by a novel ultrasonic atomization (UA) process at laboratory-scale using an industrial electrode induction gas atomization (EIGA) process with a modified electrode concept for the first time. UA allows flexibility in alloy composition due to the arc melting-based principle, while the EIGA electrode is PM manufactured from elemental powders to provide similar flexibility on a larger scale. The powders resulting from these two processes were compared with respect to size distribution, sphericity, microstructure and phase constitution, chemical composition, and interstitial impurity content. In addition, several powder batches were produced with the UA process in order to assess the process reliability and stability. The properties, quality, and quantities of UA powders perfectly meet the requests for alloy development for powder bed fusion AM, while the modified EIGA process allows the upscaling of the alloy powder quantities. Full article

In wartime Japan, folklore studies (minzokugaku) as an academic discipline emerged at the same time as the rise of the culture film (bunka eiga). Both helped mobilize peripheral areas and firmly created the image of a unitary nation. This paper focuses on Living by the Earth (Tsuchi ni ikiru, 1941), directed by Miki Shigeru, and its spinoff photo album titled People of the Snow Country (Yukiguni no minzoku, 1944). Miki filmed rural life and ordinary people in the Tohoku region under the strong influence of Yanagita Kunio, a founder of Japanese folklore studies, and published the photo album in collaboration with Yanagita. In this project, vanishing customs were paradoxically regarded as objects impossible to photograph. However, that paradox enhanced the value of the project and made it easier to construct an imagined national community through the discourse of folklore studies. Full article

TiAl-based alloys are promising light weight structural materials for high temperature applications in the field of aerospace. Recently, fabrication technologies starting from powders including powder metallurgy and additive manufacturing have been developed to overcome the difficulties in the processing, machining and shaping of TiAl-based alloys. Spherical alloy powders with different particle size distributions are usually used in these fabrication techniques. The purpose of this study is to reveal the size-dependent structural properties of a high-Nb TiAl powder for these fabrication technologies starting from powders. A high-Nb TiAl pre-alloyed powder with nominal composition of Ti-48Al-2Cr-8Nb (at. %) was prepared by the electrode induction melting gas atomization (EIGA) method. The phase structure and morphology of the as-atomized powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The size-dependent structural changes of the as-atomized powders with different sizes were studied by differential scanning calorimetry (DSC) and in situ high temperature XRD. It was found that with decreasing the powder size, the content of the γ-TiAl phase decreases and the α₂-Ti₃Al phase increases. The α₂-Ti₃Al to γ-TiAl phase transformation was found in the temperature range of 600–770 °C. Based on the present work, the structural characteristics of TiAl powders are strongly dependent on their particle size, which should be considered in optimizing the process parameters of TiAl alloys fabricated from powders. Full article

This article seeks to cast light on some of Hani Susumu’s theoretical and practical contributions to post-war Japanese documentaries. The article will also show how he created a documentary school at Iwanami Eiga based on authors’ closeness to the filmed object. This is crucial in order to understand the tendencies that developed in non-fiction films from the late 1950s. Hani’s influence can be seen in the leaders of militant cinema, Tsuchimoto Noriaki and Ogawa Shinsuke, who were trained at Iwanami Eiga. However, some of his theoretical writings, together with his documentary films Hōryūji (1958) and Gunka Ken 2 (1962), reveal how his singular subjective realism is applied to unusual shooting objects, landscapes. This article assesses this lesser-known aspect of Hani’s work and its links to certain developments in Japanese documentary films led by other filmmakers, such as Teshigahara Hiroshi and Adachi Masao, which have not yet been addressed. Full article

In the early 1940s Japan, cinematographers and critics feverishly discussed the notions of immediacy and authorship in relation to documentary practices. The status of cinematographers as the authors of the images that they shot was particularly questioned in those conversations due to the mechanical nature of the motion picture camera. This article mainly focuses on the discussions in the journal Eiga Gijutsu (Film Technology) in 1941–1942 over the notion of culture, and examines how cinematographers imagined their new roles in documentary practices in the cinema. Full article

Several efficient algorithms to conduct pairwise comparisons among large databases of protein structures have emerged in the recent literature. The central theme is the design of a measure between the C_α atoms of two protein chains, from which dynamic programming is used to compute an alignment. The efficiency and efficacy of these algorithms allows large-scale computational studies that would have been previously impractical. The computational study herein shows that the structural alignment algorithm eigen-decomposition alignment with the spectrum (EIGAs) is robust against both parametric and structural variation. Full article

Straipsnyje aprašomas gana retas atvejis – ūminis glomerulonefritas, susijęs su mikoplazmine pneumonija. Literatūros duomenimis, mikoplazminė infekcija gali būti susijusi su įvairaus pobūdžio inkstų pažeidimu, tačiau mūsų stebėtu atveju inkstų liga nedaug skyrėsi nuo klasikinio ūminio poinfekcinio glomerulonefrito. Ryškiausias skirtumas – tai, kad inkstų ligos požymių atsirado beveik vienu metu su kvėpavimo takų ligos simptomais, o ne praėjus bent vienai savaitei. Ligos eiga ir baigtis buvo gera. Full article

Išeminė širdies liga ir cukrinis diabetas yra dvi glaudžiai susijusios ligos. Sunkiausia išeminės širdies ligos forma – miokardo infarktas. Ūminio miokardo infarkto eiga ir prognozė cukriniu diabetu sergantiems ligoniams yra daug blogesnė nei to paties amžiaus ir lyties cukriniu diabetu nesergantiems ligoniams. Jau seniai ieškoma, kaip pagerinti tokių ligonių būklės vertinimą ir rizikos patvirtinimą. Daug žadanti sritis – autonominės širdies ir kraujagyslių sistemos bei jos pokyčių, sergant šiomis ligomis, tyrimai. Parasimpatinė ir simpatinė širdies dažnio moduliacija jau daug metų tiriama įvairiuose lygmenyse, tačiau mechanizmai yra sudėtingi ir iki šiol nepakankamai ištirti. Straipsnyje pateikiama literatūros apžvalga apie autonominės širdies ir kraujagyslių sistemos reguliacijos mechanizmų tyrimus bei jų pokyčius sergant miokardo infarktu ir cukriniu diabetu, taip pat apie šiuolaikinius autonominės širdies reguliacijos tyrimo metodus bei galimus intervencinius ir medikamentinius autonominio tonuso keitimo būdus. Norint geriau suprasti patologinių pokyčių atsiradimą ir eigą sergant miokardo infarktu ir cukriniu diabetu, straipsnyje pateikiama ir trumpa širdies ritmo vedlio funkcijos bei normalios autonominės širdies inervacijos bei širdies dažnio reguliacijos apžvalga. Full article