著者

Son Thanh Nguyen Tadachika Nakayama Masatoshi Takeda Nguyen Ngoc Hieu Tsuyoshi Takahashi

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.61, no.8, pp.1510-1516, 2020-07-01 (Released:2020-07-25)

参考文献数

32

被引用文献数

4

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Thermal barrier coatings (TBCs) are necessary to protect nickel-based alloy blades of gas turbine against oxidation and thermal fatigue in high-temperature operating conditions. Ceramic materials, which are very good natural thermal insulator, attract the most interests from engineers and scientists. However, the brittleness of ceramics is a major obstacle for utilizing them as the TBCs, which are also required very good damage tolerance against physical impacts. The cracks appear on the blade surfaces during its operation can lead to the severe failure. In this research, a composite of Y2Ti2O7 and Ni was developed as a self-crack healing material to overcome this problem. The crack-healing behavior is investigated by using Vickers indenter to create cracks on the composite surface intentionally, followed by annealing in an oxidizing environment. It is found that the main crack-healing mechanism is the filling of NiO, which was formed from the oxidation of the Ni fillers, into the cracks. Complete heal of cracks is achieved with 10 vol% Ni filler, which is confirmed by X-ray diffraction and scanning electron microscopy. Thermal conductivity and Weibull distribution for the strength of the composite were also investigated to find the appropriate volume fraction of Ni nanoparticles in this self-healing material.

著者

Sungho Lee Jong Yeong Oh Soichiro Mukaeyama Shi-Hai Sun Takayoshi Nakano

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.60, no.9, pp.1779-1784, 2019-08-01 (Released:2019-08-25)

参考文献数

33

被引用文献数

6

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Selective laser melting (SLM) is widely used for the additive manufacturing (AM) of metal components, which can produce net shape complex geometries. Novel titanium alloy/bioactive glass composites were successfully fabricated via SLM method for biomedical applications. The fabricated composites contained a Ti5Si3 phase, which resulted from the reaction between the titanium alloy and the bioactive glass. The phase can improve the bonding strength between composite and bone. Additionally, the remained amorphous bioactive glass phase could improve bioactivity. The present study opens a new avenue for developing new titanium alloy/bioactive glass composites with optimal bioactivity and bonding strength with the bone.

著者

Yuchen Liu Sosuke Kondo Hao Yu Kiyohiro Yabuuchi Ryuta Kasada

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.61, no.5, pp.955-962, 2020-05-01 (Released:2020-04-25)

参考文献数

32

被引用文献数

5

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Oxide Dispersion Strengthening copper (ODS-Cu) alloy has high strength, high thermal conductivity and superior irradiation resistance which are needed for fusion reactor divertor components. In this study, specimen size dependence of the yield stress in Cu and ODS-Cu which were made by mechanical alloying and hot pressing was investigated by micro-pillar compression test. The distributions of yield stress values were different between the sizes, 1, 3 and 5 µm cubic micro-pillars, which can be explained by the inhomogeneous spatial distributions of both the crystallographic grain in matrix and oxide-particles.

著者

Jovana Ruzic Ikumu Watanabe Kenta Goto Takahito Ohmura

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.60, no.8, pp.1411-1415, 2019-08-01 (Released:2019-07-25)

参考文献数

22

被引用文献数

10

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A new approach of nano-indentation measurements at elevated temperatures has been developed to evaluate a temperature-dependent mechanical behavior of heat resistant alloys on a submicron scale, where the measurement is conducted in an inert atmosphere to prevent the surface oxidation of a sample and heat an indenter passively. The developed approach enables us to perform nano-indentation testing with a diamond indenter in the temperature range of 23∼800°C. The developed approach has been applied to gamma single-phase single-crystal of a nickel-based superalloy. Then the degradations of the sample surface and the indenter tip have been discussed in this case.

著者

Shiho Miyazaki Masahiro Kusano Dmitry S. Bulgarevich Satoshi Kishimoto Atsushi Yumoto Makoto Watanabe

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.60, no.4, pp.561-568, 2019-04-01 (Released:2019-03-25)

参考文献数

31

被引用文献数

17

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The selective laser melting could be employed in fabrication of near-net shape products for airplane and biomedical applications from Ti–6Al–4V alloy, which is difficult-to-process material. In this method, the localized laser irradiation forms the unique Ti–6Al–4V microstructures which correspond to the laser scanning patterns and local thermal history as it could be observed from sample cross-sections with OM or SEM. In this study, the effects of heat treatments on mechanical properties of Ti–6Al–4V samples produced by selective laser melting are discussed based on quantitative analysis of microstructures with image processing and machine learning tools. It was found that microstructures of heat-treated samples retained their original morphologies and secondary α phase precipitated regularly at β grain boundaries with increased treatment time. These microstructures were appropriately segmented and classified. Each α particle geometrical characteristics were successfully extracted and evaluated by image analysis. Importantly, the hardness of the heat-treated samples was lower compared to that of as-built ones and it tended to increase with the area fraction of α phase, the α particle width, and the nearest neighbor distance between α particles.

著者

Yoshihiro Kayanuma Shoei Mizuhashi Yuichiro Shindo

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.59, no.9, pp.1405-1410, 2018-09-01 (Released:2018-08-25)

参考文献数

22

被引用文献数

3

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Precious metals from industrial scraps generated by manufacturing processes have been extensively recycled. For these recycles, it is necessary to ensure confidentiality when dealing with the scraps and to perform the recycling operation in an isolated lot with a high recovery ratio, short operation time, and low treatment cost. In recent years, three challenges have emerged in scrap recycling. The first is the decrease in the precious metal content in the scrap, owing to the substitution of precious metals with other non-ferrous metals. The second is the contamination of the scrap with metals that are not present in natural ores. These contaminations pose challenges in the extraction and purification of precious metals. The third challenge is the adherence to Japan’s environmental regulations, which have been tightened recently, restricting the continuous use of some chemicals such as nitric acid. In this report, some efforts of precious metal recycling companies to overcome these challenges are discussed. This Paper was Originally Published in Japanese in Japan Inst. Met. Mater. 81 (2017) 152–156.

著者

Sradhanjali Singh Bansi Dar Nayak Rama Chandra Mohanty Swaranjit S. Cameotra Lala Beheri Sukla Dong-Jin Kim

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.53, no.11, pp.2004-2010, 2012-11-01 (Released:2012-10-25)

参考文献数

21

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Malanjkhand copper project, Madhya Pradesh, India, generates a lot of lean sulphidic ores containing chalcopyrite (∼0.3% of copper) with traces of oxidized, semi-oxidized and secondary sulfides. EPMA analysis shows that the granitic rock samples have plagioclase feldspar, orthoclase feldspar and quartz as major constituents within which the ore minerals are sparsely distributed. Due to the complex structure and low solubility of the sulphide-bearing granitic rock, the dissolution of copper from the hard matrix is difficult. The present study deals with change in crystallographic and chemical nature of the mineral system present in the host rock. In an attempt to increase copper recovery, the ore was subjected to heating at 600°C under normal atmospheric conditions. This heat treatment resulted in enhanced copper recovery, up to 98% within 60 days of progressive leaching.

著者

Yoshihito Kawamura Michiaki Yamasaki

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.48, no.11, pp.2986-2992, 2007-11-01 (Released:2007-10-25)

参考文献数

13

被引用文献数

230 452

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We investigated the formation and mechanical properties of Mg97Zn1RE2 alloys with long-period stacking ordered (LPSO) structures by examining RE = Y, La, Ce, Pr, Sm, Nd, Gd, Dy, Ho, Er, Tb, Tm and Yb. The LPSO phase developed for RE = Y, Dy, Ho, Er, Gd, Tb and Tm. LPSO Mg-Zn-RE alloys are either type I, in which the LPSO phase forms during solidification: Mg-Zn-Y, Mg-Zn-Dy, Mg-Zn-Ho, Mg-Zn-Er and Mg-Zn-Tm, or type II, in which the LPSO phase is nonexistent in as-cast ingots but precipitates with soaking at 773 K: Mg-Zn-Gd and Mg-Zn-Tb. The criteria for REs that form an LPSO phase in Mg-Zn-RE alloys are discussed. Mg-Zn-RE alloys with an LPSO phase, which were worked by hot extrusion, include high strength both at ambient and elevated temperatures, and good ductility. Their tensile yield strength, ultimate strength and elongation were 342–377 MPa, 372–410 MPa and 3–9%, respectively at ambient temperature, and 292–310 MPa, 322–345 MPa and 4–13% at 473 K. The LPSO Mg-Zn-RE alloys are promising candidates for lightweight structural materials.

著者

Kodai Murasawa Masato Takamura Masayoshi Kumagai Yoshimasa Ikeda Hiroshi Suzuki Yoshie Otake Takayuki Hama Shinsuke Suzuki

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

pp.M2017380, (Released:2018-06-01)

参考文献数

22

被引用文献数

6

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Neutron diffraction profile analysis using the whole profile fitting method is useful for obtaining microscopic information on metallic materials. To determine an appropriate fitting approach for obtaining reasonable and non-arbitrary results, we applied diffraction line profile analyses using the Convolutional Multiple Whole Profile (CMWP) method to diffraction patterns obtained using the Engineering Materials Diffractometer (TAKUMI, BL19) at the Materials and Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). The tensile specimens of 780 MPa grade bainitic steel were uniaxially stretched until the plastic strain reached a value of 0.05. We performed CMWP analyses on the obtained diffraction patterns during tensile test with various initial parameters of dislocation density and crystallite size. These parameters were optimized in the fitting procedures to minimize the weighted sums of squared residuals (WSSRs). Following this approach, we found that unsuitable initial parameter values resulted in unreasonable convergence. Therefore, initial fitting parameters should be chosen to ensure that the initial profiles are as broad as possible. Reasonable results were obtained following this suggestive approach even when the strain anisotropy parameter is set to arbitrary values.

著者

Cunying Xu Yawei Liu Yixin Hua Jian Li Qibo Zhang

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.58, no.3, pp.377-382, 2017-03-01 (Released:2017-02-25)

参考文献数

24

被引用文献数

1 8

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The electrochemical and chemical behaviors of titanium were examined in aluminum chloride-1-butyl-3-methylimidazolium chloride (AlCl3-BMIC) ionic liquid. The reduction of Ti(IV) in AlCl3-BMIC occurs in three consecutive steps: Ti(IV) → Ti(III) → Ti(II) → Ti, and Ti(III) ion can quickly react with Cl− anion to form sparingly soluble TiCl3. However, No elemental titanium can be obtained in either acidic or basic AlCl3-BMIC melt. Metal titanium can be oxidized to Ti(II) by Ti(IV) in AlCl3-BMIC melt. In addition, the anodic oxidation rate of titanium obviously increases in the presence of Ti(IV) and Ti(III) ions, suggesting that the anodic dissolution of titanium involves chemical dissolution. These results indicate that it is difficult to nucleate or stabilize pure titanium in ionic liquid, which makes pure titanium deposition quite difficult.

著者

Norihito Sakaguchi Fuuta Yamaki Genki Saito Yuji Kunisada

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.58, no.10, pp.1341-1345, 2017-10-01 (Released:2017-09-25)

参考文献数

21

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We analyzed the spatial distribution of Ca dopants in α-SiAlON by using a statistical approach that analyzed a high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) image. By evaluating the image intensity of each atomic column, we found that the intensity deviation of columns with Ca atoms was twice that of other atomic columns. The results of HAADF-STEM image simulation suggested that there was a long-range repulsive interaction along the [0001] direction between pairs of Ca atoms in the same Ca column. Moreover, correlation of image intensities in neighboring Ca columns suggested the existence of a short-range repulsive force between first-nearest-neighbor Ca atoms. The origin of such anisotropic interactions between pairs of Ca atoms will be discussed.

著者

酒井 宏明 井口 泰孝 曹 勇

出版者

The Japan Institute of Metals and Materials

雑誌

まてりあ : 日本金属学会会報 (ISSN:13402625)

巻号頁・発行日

vol.45, no.1, pp.3-7, 2006-01-20