Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/met9040468

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/isijinternational.ISIJINT-2017-758

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2320/matertrans.M2016407

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/isijinternational.ISIJINT-2016-712

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/tetsutohagane.TETSU-2016-057

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.scriptamat.2015.02.001

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/tetsutohagane.100.688

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2320/matertrans.M2013427

Language：Japanese   Publisher：The Japan Institute of Metals and Materials  

<p>Microscopic stress-strain curves were obtained by applying stress measurements using the HR-EBSD method and strain measurements using the DIC method to the same field of view in SEM <i>in-situ</i> tensile tests. From the analysis of these microscopic stress-strain curves, yield stress map and work hardening rate map were successfully produced. The relationship between these mechanical property value maps and the microstructure is investigated. The yield stress maps confirm the tendency of the local yield stress to show different values for different grains, but the Schmid factor alone cannot explain the magnitude of the yield stress. When adjacent grains with significantly different Schmid factors deformed cooperatively, the yield stress is found to increase as a result of stress partitioning. Localized regions of extreme work hardening rates were observed in the work hardening rate maps. These regions were located close to grain boundaries with low <i>m</i>′ values where slip transfer was difficult and an interruption of the slip bands was observed. In addition, the rate of increase of GND density with strain was large in these regions. From these results, it can be understood that the extreme work hardening rates are due to increased back stresses caused by the accumulation of dislocations on low <i>m</i>′ grain boundaries.</p>

DOI： 10.2320/jinstmet.j202404

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CiNii Research

Language：English   Publisher：The Japan Institute of Metals and Materials  

<p>The strain-rate dependence of slip persistence in TiZrNbHfTa was investigated using microcantilever bending tests instead of conventional single-crystal tensile tests. These tests were performed using micrometre-sized cantilevers fabricated within a grain of the polycrystalline material, and the ψ–χ relationship was obtained in detail. Bending tests were conducted in two strain rates to determine the ψ–χ relationship. The results showed that the slip plane macroscopically persisted on the {112} plane in the high-strain-rate test, while in the low-strain-rate test, the apparent slip plane roughly coincided with the plane where the maximum shear stress was applied. Detailed tracing of the slip bands, using atomic force microscopy, on the specimen surface showed that the slip plane was microscopically persisted on the {112} plane in high-strain-rate tests, while in low-strain-rate tests, the slip plane often cross-slipped between the {112} and {110} planes.</p>

DOI： 10.2320/matertrans.mt-ma2024010

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CiNii Research

Publishing type：Research paper (scientific journal)   Publisher：Materials Science and Engineering: A  

Plastic anisotropy in the yield stress of pearlitic steels evolved by drawing was studied. The tension and compression tests were performed in parallel and perpendicular directions to the drawing direction. The yield stress in the parallel tension and vertical compression tests increased with the increase in drawing strain. On the other hand, in the parallel compression, the yield stress decreased significantly at the small drawing strain and then increased at the larger strain. The difference between the yield stress at the tension and at the compression did not change largely after the start of the drawing. The observation of microstructure indicated no significant heterogeneity of the deformation microstructure and texture at the different locations in the radial direction of the drawn samples, meaning that the plastic anisotropy was brought by reasons other than the non-uniformity of the deformation condition. The measurement of the distribution of the local misorientation in ferrite suggested the large plastic deformation even at smaller strain by drawing. This result indicates that the residual stress in plastically deformed ferrite brings back stress, which can be the source of the plastic anisotropy.

DOI： 10.1016/j.msea.2024.146380

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Publisher：ACS Applied Energy Materials  

A type-I clathrate Ba8CuxSiyGe46-x-y ingot consisting of millimeter-sized grains with different crystallographic orientations was synthesized by the Czochralski method. The lower part of the ingot contained more Cu and Ge within the clathrate phase. The electrical resistivities of the top, middle, and bottom of the ingot at 550 °C were 0.78, 1.72, and 1.55 mΩ·cm, respectively. The differences in these values are consistent with the carrier concentration and calculated anisotropic effective mass of the electrons, which are based on the actual chemical composition and crystal orientation, respectively. The resistivity of the top part with few grain boundaries is less than a quarter of that of the hot-pressed sample with a similar composition. Despite the different carrier concentrations, the Seebeck coefficient of all parts had similar values of approximately −120 μV/K at 550 °C. The thermal conductivity at 350 °C was approximately 3.0 W/m·K for top part and 2.5 W/m·K for middle and bottom parts, about 1.5-1.8 times larger than those of previous reported hot-pressed samples. The power factor and dimensionless figure of merit ZT value of the top reached 18.8 μW/cm·K2 and 0.34, respectively. These results indicate that fabrication by the Czochralski method can improve the thermoelectric performance of Ba8CuxSiyGe46-x-y clathrates.

DOI： 10.1021/acsaem.3c02961

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Language：Japanese   Publisher：The Iron and Steel Institute of Japan  

<p>A modified continuum composite model was utilized to analyze the stress–strain behavior of as-quenched steels with a fully martensitic microstructure. The model was employed to express the stress–strain curves obtained by a simple tensile test and those obtained by forward and backward loading using a simple shear test machine. The study confirmed that the model can represent the stress–strain behavior under both forward and backward deformation. In addition, the evolution of local strain distributions during plastic deformation was investigated using a digital image correlation method. The strain distributions and their evolution during deformation were qualitatively represented using this model. The discrepancies between the model calculations and experiments are due to the limitations of the iso-work assumption and the impact of slip deformation on the macroscopic work-hardening behavior of martensitic steels. Highly strain-concentrated regions aligned along the longitudinal direction of the lath and block, known as in-lath-plane slips, may not play an important role in the work-hardening behavior of as-quenched martensitic steels. However, the other slips, namely the out-of-lath slip, may play a significant role in the work hardening of as-quenched martensitic steels.</p>

DOI： 10.2355/tetsutohagane.tetsu-2023-063

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CiNii Research

Language：English   Publisher：The Iron and Steel Institute of Japan  

<p>A modified continuum composite model was utilized to analyze the stress–strain behavior of as-quenched steels with a fully martensitic microstructure. The model was employed to express the stress–strain curves obtained by a simple tensile test and those obtained by forward and backward loading using a simple shear test machine. The study confirmed that the model can represent the stress–strain behavior under both forward and backward deformation. In addition, the evolution of local strain distributions during plastic deformation was investigated using a digital image correlation method. The strain distributions and their evolution during deformation were qualitatively represented using this model. The discrepancies between the model calculations and experiments are due to the limitations of the iso-work assumption and the impact of slip deformation on the macroscopic work-hardening behavior of martensitic steels. Highly strain-concentrated regions aligned along the longitudinal direction of the lath and block, known as in-lath-plane slips, may not play an important role in the work-hardening behavior of as-quenched martensitic steels. However, the other slips, namely the out-of-lath slip, may play a significant role in the work hardening of as-quenched martensitic steels.</p>

DOI： 10.2355/isijinternational.isijint-2023-140

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CiNii Research

Language：Japanese   Publisher：The Japanese Society of Microscopy  

<p>Three-dimensional visualization of dislocations by serial sectioning of SEM-ECCI images was performed on a creep-deformed nickel-based heat-resistant alloy. By performing serial tomograms of ECCI images, a volume of approximately 5 μm × 5 μm × 0.3 μm volume was successfully reconstructed. By incorporating the crystal orientation information obtained by the SEM-EBSD method, we confirmed that the three-dimensional arrangement of dislocations, such as slip planes and cross-slip, is accurately reflected in the three-dimensional volume. Thus, serial sectioning of ECCI images enables us to observe and analyze the bulk dislocation microstructure in three dimensions in the micrometer scale range.</p>

DOI： 10.11410/kenbikyo.58.3_90

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Institute of Light Metals  

<p>Impact tests and tensile tests were conducted between 77 K and 450 K in order to elucidate the temperature dependence of absorbed-impact energy, yield stress, effective shear stress, activation volume, and activation enthalpy. The impact-absorbed energy decreased with decreasing test temperature, however, this alloy did not undergo low-temperature embrittlement although it has a bcc structure. Tensile tests showed changes in both the work-hardening rate and the temperature dependence of yield stress at approximately 150 K. This suggests a change in the mechanism behind the plastic deformation at the temperature. The temperature dependence of the activation enthalpy for dislocation glide suggests that the process of climbing over the Peierls potential (kink-pair nucleation) is the dominant mechanism for the dislocation glide from 150 K to 200 K, while the interaction between a dislocation and solute atoms dominantly controls the dislocation glide above 200 K. Superelasticity appears in stress-strain curves tested below 120 K, suggesting that the yielding is governed by transformation-induced plasticity below 120 K. The enhanced toughness at low temperatures in these alloys is discussed from the viewpoint of dislocation shielding theory.</p>

DOI： 10.2464/jilm.73.497

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

A method for obtaining microscopic and localized stress-strain curves is proposed by combining strain measurements using the digital image correlation (DIC) method with stress measurements using high-resolution electron backscattered diffraction (HR-EBSD). A dataset containing 11 steps of stress–strain information in a single subset was created by applying georeferencing to DIC strain maps and HR-EBSD stress maps measured in a deformation-interrupted microstructure. This analysis allowed us to obtain local stress-strain curves and strain energy maps of polycrystalline nickel alloys. A comparison of the stress-strain curves obtained from any subset in the map revealed that these curves show extremely diverse shapes depending on the location in the microstructure.

DOI： 10.1016/j.scriptamat.2023.115603

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Publishing type：Research paper (scientific journal)   Publisher：Scripta Materialia  

The effect of carbon on the persistence of the slip in Fe–3 mass% Si was investigated. We applied micro-sized cantilever bending tests to obtain ψ–χ relationships that enable quantitative analysis of the persistence of the slip. It was demonstrated that the result from decarburized specimens using this method is consistent with those obtained in previous studies from bulk-sized tensile test specimens. This novel method eliminates the difficulty of preparing bulk-sized single-crystal specimens for investigating the persistence of the slip. The persistence of the slip weakened in aged specimens containing 0.016 mass% C and disappeared in quenched specimens with the same carbon content, where wavy slip bands were observed. The reason for these changes in the macroscopically apparent slip plane is explained by the assumption that the frequency of nucleating kink-pair in the competitive {110} planes is a function of the resolved shear stress.

DOI： 10.1016/j.scriptamat.2023.115473

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Language：English   Publisher：Elsevier  

The effect of carbon on the persistence of the slip in Fe–3 mass% Si was investigated. We applied micro-sized cantilever bending tests to obtain ψ–χ relationships that enable quantitative analysis of the persistence of the slip. It was demonstrated that the result from decarburized specimens using this method is consistent with those obtained in previous studies from bulk-sized tensile test specimens. This novel method eliminates the difficulty of preparing bulk-sized single-crystal specimens for investigating the persistence of the slip. The persistence of the slip weakened in aged specimens containing 0.016 mass% C and disappeared in quenched specimens with the same carbon content, where wavy slip bands were observed. The reason for these changes in the macroscopically apparent slip plane is explained by the assumption that the frequency of nucleating kink-pair in the competitive {110} planes is a function of the resolved shear stress.

CiNii Research

Language：English   Publisher：Elsevier  

Body-centred cubic (bcc) high-entropy alloys exhibit high strength. However, their yield behaviour and controlling mechanisms are still ambiguous. In this study, the temperature dependence of the yield stress, effective stress, activation volume, and activation enthalpy in a polycrystalline bcc refractory high-entropy alloy of TiZrNbHfTa were measured by tensile tests at 77–750 K. At temperatures above 650 K, the temperature dependence of the yield stress disappeared, and serration appeared in stress–strain curves. By extrapolating the effective shear stress to 0 K, the Peierls stress was estimated to be 580 MPa. The value was compared with different crystals using the relationship (τ_p)/(μ) and (h)/(b) , where τ_p is the Peierls stress, μ is the shear modulus, h is the distance between the slip planes, and b is the Burgers vector. The (τ_p)/(μ) value in this study was slightly higher than that of other bcc crystals. The activation enthalpy below 260 K corresponds to that of other bcc crystals with high Peierls potentials, suggesting kink-pair nucleation is the controlling mechanism of the dislocation glide in this temperature range. Meanwhile, the activation enthalpy above 260 K deviated from the trendline, indicating the changes in the dislocation glide from the kink-pair nucleation to other one.

CiNii Research

Publishing type：Research paper (scientific journal)   Publisher：Materials Science and Engineering: A  

Body-centred cubic (bcc) high-entropy alloys exhibit high strength. However, their yield behaviour and controlling mechanisms are still ambiguous. In this study, the temperature dependence of the yield stress, effective stress, activation volume, and activation enthalpy in a polycrystalline bcc refractory high-entropy alloy of TiZrNbHfTa were measured by tensile tests at 77–750 K. At temperatures above 650 K, the temperature dependence of the yield stress disappeared, and serration appeared in stress–strain curves. By extrapolating the effective shear stress to 0 K, the Peierls stress was estimated to be 580 MPa. The value was compared with different crystals using the relationship [Formula presented] and [Formula presented], where τp is the Peierls stress, μ is the shear modulus, h is the distance between the slip planes, and b is the Burgers vector. The [Formula presented] value in this study was slightly higher than that of other bcc crystals. The activation enthalpy below 260 K corresponds to that of other bcc crystals with high Peierls potentials, suggesting kink-pair nucleation is the controlling mechanism of the dislocation glide in this temperature range. Meanwhile, the activation enthalpy above 260 K deviated from the trendline, indicating the changes in the dislocation glide from the kink-pair nucleation to other one.

DOI： 10.1016/j.msea.2023.144917

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Publishing type：Research paper (scientific journal)   Publisher：Acta Materialia  

Mg–Zn–Y alloys that contain an Mg-based long-period stacking ordered (LPSO) phase exhibit excellent mechanical properties because of the kink bands formed by plastic deformation. Such “kink-band strengthening” has attracted significant attention. Herein, we conducted deformation tests on directionally solidified single-phase LPSO Mg85Zn6Y9 alloys to investigate the kink-band strengthening mechanism. High-angular resolution electron backscatter diffraction was performed to detect misorientation between the matrices on either side of the kink bands. The misorientations corresponded to the magnitudes of the Frank vectors of the disclinations around the kink, and closely matched the estimations from geometric analysis, which supported the existence of disclinations. Moreover, the Frank vector of the kink bands increased after shear deformation, which indicates that shear deformation introduced new disclinations around the kinks. Scanning electron microscopy demonstrated that the kinks clearly obstructed basal ⟨a⟩ slip. Furthermore, scanning transmission electron microscopy of a sheared kink band revealed dislocation pile-ups on both sides of the kink/matrix interface, as well as the formation of secondary kinks that stabilized the structure against shear deformation (i.e., self-accommodation) and bend contours caused by elastic stress fields. The results suggest that disclinations behave as long-range obstacles to dislocation motion (e.g., by reducing the increase in kink-band self-energy or by the elastic stress field of disclinations). We believe that this study will play a key role in identifying the factors responsible for kink-band strengthening in LPSO-phase Mg alloys and in understanding the phenomena underlying the strengthening mechanism.

DOI： 10.1016/j.actamat.2023.118785

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Materials  

In this study, pure titanium equivalent to Grade 1 was subjected to tensile tests at strain rates ranging from 10−6 to 100 s−1 to investigate the relationship between its mechanical properties and its twinning and slip. Deformation properties and microstructures of samples having average grain sizes of 210 μm (Ti-210), 30 μm (Ti-30), and 5 μm (Ti-5) were evaluated. With increasing strain rates, the 0.2% proof stress and ultimate tensile strength increased for all samples; the fracture strain increased for Ti-210, decreased for Ti-5, and changed negligibly for Ti-30. Comparing high (100 s−1) and low (10−6 s−1) strain rates, twinning occurred more frequently in Ti-30 and Ti-210 at high strain rates, but the frequency did not change in Ti-5. The frequency of 1st order pyramidal slip tended to be higher in Ti-30 and Ti-5 at low strain rates. The higher ductility exhibited by Ti-210 at high strain rates was attributed to the high frequency of twinning. In contrast, the higher ductility of Ti-5 at low strain rates was attributed to the activity of the 1st order pyramidal slip.

DOI： 10.3390/ma16020529

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Publisher：28th IFHTSE 2023 Congress  

Quenched martensitic steels are known to show the characteristic feature of stress-strain relations, with extremely low elastic limits and very large work-hardening. The continuum composite approach is one way to express this characteristic feature of stress-strain curves. Although the overall stress-strain curves, as a function of alloy chemistries of steels, were well represented by this approach, the relationship between the macroscopic deformation behaviors and microstructural information is yet to be clarified. A high-spatial-resolution digital image correlation analysis was conducted to demonstrate the possible unit size corresponding to the microstructure. The continuum composite approach model was also modified to consider the size effect of the microstructure on the stress-strain curves of the as-quenched martensitic steels. Strain concentrations were observed at various boundaries, including lath boundaries, and the characteristic microstructural size was also predicted by the present model, which is smaller than the reported spacing between adjacent strain-concentrated regions.

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Iron and Steel Institute of Japan  

<p>The creep deformation behavior and microstructure of a N-containing steel expected to exhibit high creep strength and excellent oxidation resistance were investigated. Even for steel with a high W content, it was possible to form a martensitic microstructure by adding a sufficient amount of N. Comparison of the microstructures of the N-containing steel and a C-containing steel confirmed that the two steels have the same crystal orientation relationship. The N-containing steel precipitated with the Laves phase as a strengthening phase displayed a higher creep strength than conventional steel under relatively high stress. However, the superiority of the creep strength of the N-containing steel relative to the conventional steel decreased under low stress. The stress exponent of the N-containing steel was different from those of the C-containing steel and the conventional steel. This deference considered to be ascribed to the difference of variation behavior of dislocation density during creep deformation.</p>

DOI： 10.2355/tetsutohagane.tetsu-2022-065

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Language：English   Publisher：The Iron and Steel Institute of Japan  

<p>Quenched martensitic steels are known to show the characteristic feature of stress–strain relations, with extremely low elastic limits and very large work-hardening. The continuum composite approach is one way to express this characteristic feature of stress–strain curves. Although the overall stress–strain curves, as a function of alloy chemistries of steels, were well represented by this approach, the relationship between the macroscopic deformation behaviors and microstructural information is yet to be clarified. A high-spatial-resolution digital image correlation analysis was conducted to demonstrate the possible unit size corresponding to the microstructure. The continuum composite approach model was also modified to consider the size effect of the microstructure on the stress–strain curves of the as-quenched martensitic steels. Strain concentrations were observed at various boundaries, including lath boundaries, and the characteristic microstructural size was also predicted by the present model, which is smaller than the reported spacing between adjacent strain-concentrated regions.</p>

DOI： 10.2355/isijinternational.isijint-2022-114

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：The Iron and Steel Institute of Japan  

<p>In this study, the cleavage fracture of the C14 Fe₂W Laves phase was investigated by first-principles calculations and crystal orientation analysis using scanning electron microscopy. Trace analysis of the orientations of cleavage planes revealed that cleavage fracture occurred in five types of crystal planes: (0001), {1<span style="text-decoration: overline;">1</span>00}, {11<span style="text-decoration: overline;">2</span>0}, {1<span style="text-decoration: overline;">1</span>01}, and {11<span style="text-decoration: overline;">2</span>2}. Among these fractures, the fracture at (0001) is the most preferable. From, the first-principle calculations of the surface energy for fracture, Young’s modulus, and Poisson’s ratio, the minimum fracture toughness value of 1.62 MPa·m^1/2 was obtained at (0001). The tendency of the calculated fracture toughness to become larger with high indexed planes is almost the same as the frequency of the types of cleavage planes in the trace analysis. It was concluded that the fracture toughness of the C14 Fe₂W Laves phase is controlled by the surface energy for fracture and Young’s modulus.</p>

DOI： 10.2355/isijinternational.isijint-2022-122

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：The Iron and Steel Institute of Japan  

<p>Resistance to Sulfide Stress Cracking (SSC) caused by local hard zones of pipe inner surface has been required in low alloy linepipe steel. In this study, using two samples with different surface hardness, the detailed SSC initiation behavior was clarified by four-point bend (4PB) SSC tests in which immersion time and applied stress were changed in a sour environment containing 0.15 bar hydrogen sulfide (H₂S) gas. SSC cracks occurred when the applied stress was higher than 90% actual yield strength (AYS) in higher surface hardness samples over 270 HV0.1. From the fracture surface observation of SSC crack sample, it was found that the mechanism gradually shifted from active path corrosion (APC) to hydrogen embrittlement (HE), and that the influence of APC mechanism remained partially in the process of SSC initiation at the tip of corrosion pit or groove. The polarization measurement in the 4PB SSC test showed that the anodic and cathodic reactions (especially cathodic reactions) were activated when the applied stress was 90% AYS or higher. The FEM coupled analysis simulating the stress and strain concentration at the bottom tip of the corrosion groove and the hydrogen diffusion and accumulation was carried out. The principal stress in the tensile direction showed the maximum value at 0.04–0.06 mm away from the tip of the corrosion groove, and the hydrogen accumulation became the maximum. It was analytically found that the SSC crack initiated and propagated with HE mechanism dominated type when the threshold value of about 0.82 ppm is exceeded.</p>

DOI： 10.2355/isijinternational.isijint-2022-236

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Language：Japanese   Publisher：The Japan Institute of Metals and Materials  

DOI： 10.2320/materia.61.543

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.2355/tetsutohagane.TETSU-2022-013

Language：Japanese   Publisher：The Japan Institute of Light Metals  

<p>The mechanical properties of JISAC8A alloys (Al-12%Si-1%Mg-1%Ni-1%Cu alloy) fabricated by laser-based powder bed fusion (LB) or electron-based powder bed fusion (EB) or gravity casting (CAST) were studied by means of tensile tests at room temperature and 300°C. These alloys were under two types of heat-treatment sequences. One was a T6 treatment, which was corresponding to the heat treatment at 500°C for 2h and 170°C for 4 h, followed by the annealing at 300°C for 10 h. Another was directly annealed at 300°C for 10 h after the fabrication. In the annealed specimens without T6 treatment, the LB alloy showed the highest strength and best elongation at room temperature and 300°C, because eutectic Si particles and Al-Ni-Cu-Fe compounds formed very fine network structure in Al matrix. In the annealed specimens with T6 treatment, the tensile strength at room temperature did not depend on the fabrication methods but the LB alloy showed the best elongation because of finer and isotropic shape of secondary phase particles. The annealed CAST alloy showed the highest strength at 300°C, and the annealed LB alloy showed the lowest strength at 300°C.</p>

DOI： 10.2464/jilm.72.206

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CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.2464/jilm.72.206

Language：Japanese   Publisher：The Iron and Steel Institute of Japan  

<p>Resistance to Sulfide Stress Cracking (SSC) caused by local hard zones of pipe inner surface has been required in low alloy linepipe steel. In this study, using two samples with different surface hardness, the detailed SSC initiation behavior was clarified by four-point bend (4PB) SSC tests in which immersion time and applied stress were changed in a sour environment containing 0.15 bar hydrogen sulfide (H₂S) gas. SSC cracks occurred when the applied stress was higher than 90% actual yield strength (AYS) in higher surface hardness samples over 270 HV0.1. From the fracture surface observation of SSC crack sample, it was found that the mechanism gradually shifted from active path corrosion (APC) to hydrogen embrittlement (HE), and that the influence of APC mechanism remained partially in the process of SSC initiation at the tip of corrosion pit or groove. The polarization measurement in the 4PB SSC test showed that the anodic and cathodic reactions (especially cathodic reactions) were activated when the applied stress was 90% AYS or higher. The FEM coupled analysis simulating the stress and strain concentration at the bottom tip of the corrosion groove and the hydrogen diffusion and accumulation was carried out. The principal stress in the tensile direction showed the maximum value at 0.04-0.06 mm away from the tip of the corrosion groove, and the hydrogen accumulation became the maximum. It was analytically found that the SSC crack initiated and propagated with HE mechanism dominated type when the threshold value of about 0.82 ppm is exceeded.</p>

DOI： 10.2355/tetsutohagane.tetsu-2022-013

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Language：Others   Publishing type：Research paper (scientific journal)  

In order to clarify the effects of grain boundary, grain size and deformation temperature on twinning deformation in polycrystalline commercially pure titanium, active twinning systems during compression deformation at temperatures from 25 °C to 800 °C investigated using SEM/EBSD techniques. Four twinning systems were confirmed to operate under compression at 10% strain in a deformation temperature dependent manner: {112̅1} and {112̅2} twins were observed only at relatively low temperatures (e.g. ≦ 400 °C), while, {101̅1} twins were observed at relatively high temperatures (e.g. ≧ 400 °C), and {101̅2} twins formed at every tested temperature (25 °C–800 °C). Our results suggested that the effects of strain concentration at grain boundaries on twinning differ based on the active twinning systems, which are affected by: 1) the difference in the formation temperature ranges between single-crystal and polycrystalline specimens, 2) the ratio of the number of deformation twins touching grain boundaries to the total number of deformation twins, and 3) grain size dependence.

DOI： 10.1016/j.jallcom.2021.161154

Language：Others   Publishing type：Research paper (scientific journal)  

Cleavage fracture of C14 Fe2W Laves phase was investigated using crystal orientation measurement with scanning electron microscopy and first-principles calculations. Trace analysis of the orientations of cleavage planes reveals that cleavage fracture occurred at five types of crystal planes of (0001), {1100}, {1120}, {1101} and {1122}, among which the fracture at (0001) is the most preferable. The first-principle calculations of the surface energy for fracture, Young's modulus, and Poisson's ratio showed that the minimum fracture toughness value of 1.62 MPa·m1/2 was obtained at (0001). The tendency that the values of calculated fracture toughness become larger with the higher indexed planes is almost the same as the frequency of the types of cleavage planes in the trace analysis. It is concluded that the fracture toughness of C14 Fe2W Laves phase is controlled by the surface energy for fracture and Young’s modulus.

DOI： 10.2355/tetsutohagane.TETSU-2021-069

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Others   Publishing type：Research paper (scientific journal)  

Slip properties of TiZrNbHfTa were evaluated to obtain ψ–χ relationships, where χ is defined as the angle between the maximum shear stress plane and (1¯01). ψ is defined as the angle between the apparent slip plane and (1¯01). Bending tests were conducted with micrometer-sized cantilevers fabricated from a single grain with a focused ion beam. Slip bands appear to be straight on a micrometer length-scale, as for Fe–Si alloys, which suggests a persistent slip. However, the ψ–χ relationship indicated that ψ is nearly the same as χ, suggesting that there is no persistent slip. Detailed observations with an atomic force microscope confirm that cross-slipping is so frequent at a sub-micrometer length-scale that the slip bands appear to be straight and the maximum shear stress plane is observed on a micrometer length-scale. Here, TiZrNbHfTa shows abnormally frequent cross-slipping, which is a novel characteristic of high-entropy body-centered cubic alloys.

DOI： 10.1016/j.scriptamat.2021.113895

Language：Others   Publishing type：Research paper (scientific journal)  

In this study, we conducted a quantitative evaluation of dislocation density by scanning electron microscopy electron channeling contrast imaging for α grains of a Ti-6Al-4V alloy deformed at room temperature. The depth of visibility of dislocations is experimentally measured as 140 to 160 nm by a serial sectioning observation. This result is compared with the theoretical value and applied to evaluate dislocation density. These factors confirm that the theoretically calculated value of the depth of visibility, at 5 to 6 times the extinction distance, is valid for the hexagonal close-packed Ti alloy.

DOI： 10.1093/jmicro/dfaa060

Language：Others   Publishing type：Research paper (scientific journal)  

A quantitative evaluation method of a serration deformation behavior by a dead-weight tensile test combined with a strain measurement by a DIC method is proposed. This method applies to binary solid solution aluminum alloys and a ternary cluster strengthened aluminum alloy. In the dead-weight tensile test, the serrated flow was measured as a stress-strain curve with a stepped-shape divided into two stages of a stress rising phase and a strain burst phase. By adopting this tensile test, the serration deformation behavior can be measured with an extremely reproducibility. It was confirmed that an elastic deformation occurs predominantly in the stress rising phase, and this deformation behavior is discussed in relation to the concentration of solid solution elements. Propagation of PLC bands has occurred in the strain burst phase. An activation volume obtained from the strain rate in the PLC bands was in good agreement with a calculated value based on a distribution interval assuming a regular square distribution of solute elements. For the ternary alloy strengthened by clusters, it is also shown that this method can be applied to the qualitative estimation of the change in the residual amount of the solid solution element in the matrix during natural aging.

DOI： 10.1016/j.msea.2021.141277

Language：English   Publishing type：Research paper (scientific journal)  

Language：Others   Publishing type：Research paper (scientific journal)  

Slip operation factor (SOF), which considers the effect of mechanical interactions between plastically “soft” and “hard” regions, is a function of the Schmid factor (SF) and critical resolved shear stress (CRSS). It is used as an indicator to efficiently predict the ease of slip operation of metal materials at the grain level. While SOF could predict strain distributions, it was not compliant to the prediction of those for individual slip systems. Additionally, the contribution of secondary slip systems was disregarded in the SOF. In this study, the SOF was first extended to adapt to individual slip systems. This extended and generalized form of the SOF was called SOFS. Next, the contribution of secondary slip systems was considered in SOF, where the modified version of the SOF was called MSOF. Polycrystalline α-Ti models were built from crystal orientation maps obtained by electron back-scattered diffraction (EBSD), and the strain distributions under uniaxial tensile loading were predicted using the SOF, SOFS, and MSOF. The results obtained were compared with those obtained via crystal plasticity finite element (CPFE) analysis. The distributions obtained by the SOFS were similar to slip strain distributions for individual slip systems when single slips were dominant and the deformation was slight. The MSOF also successfully predicted the strain distributions with higher accuracy than that offered by the SOF.

DOI： 10.1016/j.mtcomm.2021.102041

Language：Others   Publishing type：Research paper (scientific journal)  

Lowering the volatile organic compound (VOC) gas detection limit toward the ppt level on a resistive-type semiconductor gas sensor was achieved by combining the material and sensor-driven designs. We fabricated Pd-SnO2 clustered nanoparticles, a material that is highly sensitive to VOC gas, on a microsensor device with a double-pulse-driven mode. This mode was involved in switching the heater-on periods at high-temperature preheating and measurement phases and the rest phase during a heater-off period between preheating and measurement phases. The electrical resistance in synthetic air and the sensor response to toluene increased as preheating temperatures increased because of an increase in the amount of O2− adsorbed on the particle surface. In addition, extending the rest time between the preheating and measurement phases significantly improved the sensor response to toluene. According to the relationship between the sensor response and toluene concentration, we improved the lower detection limit for toluene gas to below 10 ppt, with preheating and measurement temperatures at 400 and 250 °C, respectively, and rest time at 100 s. Therefore, the combination of the material and sensor-driven designs may play a key role in improving the sensor performance.

DOI： 10.1021/acsaelm.0c00902

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

In this study, the relation between the change of the magnetic properties and the creep strength with the addition of Co was investigated for ferritic steel containing 15 mass%Cr. Co addition up to 6 mass% hardly contributes to solid solution strengthening and precipitation strengthening at room temperature. However, in the range of 650 degrees C to 750 degrees C, it was confirmed that the addition of Co was effective for the creep strengthening because the steel with a larger amount of Co had higher creep strength. This creep strengthening is explained by a reduction in the diffusion rate associated with a change in magnetic properties by Co addition. The increase of the volume magnetization of the steel with increase of Co amount in the temperature range from room temperature to about 800 degrees C was confirmed. Comparing the difference in volume magnetization and the ratio of creep strain rate for steels with different amounts of Co, a clear correlation was found between the values. That is, at the temperature at which the difference in volume magnetization becomes maximum, the peak of the creep strain rate ratio was observed. This result is explained as follows. In a low temperature region where the magnetization is large or in a high temperature region above the Curie point of both steels, there is no significant difference in the creep strength between them. However, in the temperature where one steel loses the ferromagnetism but the other steel maintains ferromagnetism, a significant difference in the creep strength was observed.

DOI： 10.2355/tetsutohagane.TETSU-2020-041

Language：Others   Publishing type：Research paper (scientific journal)  

The deformation behavior and microstructure evolution of Ti-6Al-4V alloy under room temperature creep was investigated using mechanical test and scanning electron microscope observation with electron back-scatter diffraction method. The alloys were creep deformed and ruptured under initial stresses of 874 MPa, 889 MPa and 904 MPa at room temperature. The rapid stress change test revealed that creep deformation was controlled by the viscous slip motion of dislocations. The stress exponent was estimated as 59. The strain rate of acceleration creep region calculated by the Norton's law with the high stress exponent was inconsistent with that measured by the experimental creep test. Using the slip trace analysis, it was found that single dislocation slip in basal and prism were mainly activated in the early stage of creep, and multiple slips were often observed as the deformation progresses. Especially, the multiple slip including 1st pyramidal slip believed to be effective for suppressing strain rate acceleration in creep. In addition, the work hardening behavior during creep showed a strain rate dependence, indicating that the lower the strain rate is, the more work hardening occurs.

DOI： 10.2464/JILM.70.405

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1016/j.mtla.2020.100716

Language：Others   Publishing type：Research paper (scientific journal)  

© 2020 Acta Materialia Inc. We investigated the pseudo three-dimensional features of kink bands formed by the compression deformation of a directionally solidified Mg85Zn6Y9 alloy. The kink bands of interest included ridge kinks with clear surface relief and gentle kinks with almost no surface relief. Observation of surface undulation by laser microscopy and electron backscatter diffraction with serial sectioning by mechanical polishing revealed the pseudo three-dimensional morphology and crystal rotation of these kink bands. The features of the observed kink bands are explained by a pseudo three-dimensional arrangement of disclination lines.

DOI： 10.1016/j.mtla.2020.100716

Language：Others   Publishing type：Research paper (scientific journal)  

© 2020 Acta Materialia Inc. The formation process of the kink bands in a directionally solidified, polycrystalline, long-period stacking ordered (LPSO) Mg85Zn6Y9 phase during compression deformation was investigated. In-situ compression observations by scanning electron microscopy and electron backscattered diffraction analysis revealed that regions with localized crystal orientation rotation appeared before ridge kinks formed as surface relief. In this paper, it is called as pre-kink The observed pre-kinks were composed of two separate regions rotated in opposite directions to each other and distinguished from one another by the three boundaries. A transmission electron microscopy observation revealed that the boundaries of the pre-kink are sub-boundaries consisting of edge dislocation array, and both its ends are terminated within the matrix. These characteristics match the reported that of regular ridge kink boundaries. In addition, while pre-kinks do not possess the ability of complete reversibility, its boundaries are capable of moving elastically.

DOI： 10.1016/j.actamat.2020.04.051

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.matchar.2020.110282

Language：Others   Publishing type：Research paper (scientific journal)  

© 2020 Elsevier Inc. Uniaxial tension experiments and electron backscatter diffraction were performed on a bimodal Ti-6Al-4V alloy to study in situ the deformation behavior of primary hcp-Ti (αp). It was found that the strain could be accommodated by the activation of slip systems and by grain rotations. The prismatic slip was the primary slip mode of the αp. From the analysis of kernel average misorientation and geometrically necessary dislocation, it was shown that the dislocations mainly distributed in the vicinity of grain and sub-grain boundaries, and part of the dislocations distributed around slip lines. It was the dislocation activities that led to the formation of the low angle grain boundary and its transformation to the high angle grain boundary. It's important that tracking of deformation heterogeneities with significance to performance. By analyzing the rotation angle, average rotation rate, and rotation path of grains, it was shown that grain rotation heterogeneity occurred during the deformation. From the observation of the loading direction, grain rotation paths kept with the texture evolution direction of all αp. The grains activated in the basal slip gradually rotated to the ⟨101¯1⟩ pole and enhanced the intensity of the ⟨101¯1⟩ texture. Meanwhile, the grains activated in prismatic or 1st-order pyramidal slip rotated to the ⟨101¯0⟩ pole and enhanced the intensity of the ⟨101¯0⟩ texture. Grain rotation and texture evolution are related to mechanical properties.

DOI： 10.1016/j.matchar.2020.110282

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/jmicro/dfaa002

Language：English  

© 2020 The Author(s). Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) enable the visualization of three-dimensional (3D) microstructures ranging from atomic to micrometer scales using 3D reconstruction techniques based on computed tomography algorithms. This 3D microscopy method is called electron tomography (ET) and has been utilized in the fields of materials science and engineering for more than two decades. Although atomic resolution is one of the current topics in ET research, the development and deployment of intermediate-resolution (non-atomic-resolution) ET imaging methods have garnered considerable attention from researchers. This research trend is probably not irrelevant due to the fact that the spatial resolution and functionality of 3D imaging methods of scanning electron microscopy (SEM) and X-ray microscopy have come to overlap with those of ET. In other words, there may be multiple ways to carry out 3D visualization using different microscopy methods for nanometer-scale objects in materials. From the above standpoint, this review paper aims to (i) describe the current status and issues of intermediate-resolution ET with regard to enhancing the effectiveness of TEM/STEM imaging and (ii) discuss promising applications of state-of-the-art intermediate-resolution ET for materials research with a particular focus on diffraction contrast ET for crystalline microstructures (superlattice domains and dislocations) including a demonstration of in situ dislocation tomography.

DOI： 10.1093/jmicro/dfaa002

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ijplas.2019.12.001

Language：Others  

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. The effect of Fe addition on the high-temperature mechanical properties of heat-resistant aluminum alloys produced by selective laser melting (SLM) was investigated in relation to the alloy microstructures. Fe is generally detrimental to the properties of cast aluminum alloys; however, we found that Fe-containing alloys produced by SLM had improved high-temperature strength and good ductility. Microstructural observations revealed that the increase in the high-temperature strength of the alloys was due to the dispersion of fine rod-shaped Fe-Si-Ni particles unique to the SLM material instead of the cell-like structure of eutectic Si.

DOI： 10.3390/met9040468

Language：English   Publishing type：Research paper (scientific journal)  

© Copyright 2018 American Chemical Society. Multilayer hexagonal boron nitride (h-BN) is an ideal insulator for two-dimensional (2D) materials, such as graphene and transition metal dichalcogenides, because h-BN screens out influences from surroundings, allowing one to observe intrinsic physical properties of the 2D materials. However, the synthesis of large and uniform multilayer h-BN is still very challenging because it is difficult to control the segregation process of B and N atoms from metal catalysts during chemical vapor deposition (CVD) growth. Here, we demonstrate CVD growth of multilayer h-BN with high uniformity by using the Ni-Fe alloy film and borazine (B3H6N3) as catalyst and precursor, respectively. Combining Ni and Fe metals tunes the solubilities of B and N atoms and, at the same time, allows one to engineer the metal crystallinity, which stimulates the uniform segregation of multilayer h-BN. Furthermore, we demonstrate that triangular WS2 grains grown on the h-BN show photoluminescence stronger than that grown on a bare SiO2 substrate. The PL line width of WS2/h-BN (the minimum and mean widths are 24 and 43 meV, respectively) is much narrower than those of WS2/SiO2 (44 and 67 meV), indicating the effectiveness of our CVD-grown multilayer h-BN as an insulating layer. Large-area, multilayer h-BN realized in this work will provide an excellent platform for developing practical applications of 2D materials.

DOI： 10.1021/acsnano.8b03055

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acsnano.8b03055

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2320/jinstmet.J2017025

Language：Japanese   Publishing type：Research paper (scientific journal)  

© 2017 The Japan Institute of Metals and Materials. Global concerns over the environmental impact and health effects of the lead-based solders have led to the development of lead-free solder alloys. Further improvements in the reliability of lead-free solder alloys at high temperatures are required for downsizing of electronic components in vehicles. In this work, tensile and creep tests and microstructure analysis were carried out to determine the effect of Bi or Sb addition on high-temperature deformation behavior in Sn-Cu-Ni solder alloys. The addition of Bi or Sb increased the strength of the Sn-Cu-Ni solder alloys. The stress exponent was estimated to be ≥3, indicating that the high- Temperature deformation was controlled by dislocation creep. Furthermore, in both the alloys, the stress exponent observed in the low stress region was nearly equal to 3 and discontinuously increased to ≥7 in the high stress region. For Sb addition, the solute atmosphere drag mechanism was observed in the low stress region.

DOI： 10.2320/jinstmet.J2017025

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.matchar.2017.04.010

Language：English   Publishing type：Research paper (scientific journal)  

© 2017 Elsevier Inc. The microscopic factors causing tensile failure of an α/β laminated Ti-6Al-4V alloy were investigated through in situ scanning electron microscopy and sampling moiré at an ambient temperature. Specifically, multiscale in situ microscopic observations were conducted to extract the most crucial factor of the failure. Slip localization in the vicinity of an intergranular α-sheet was clarified to be the primary factor that causes failure of the Ti-6Al-4V alloy. In addition, no relationship between interfacial strain localization and macroscopic shear localization at 45 degrees against the tensile direction was observed.

DOI： 10.1016/j.matchar.2017.04.010

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2320/jinstmet.J2016069

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/tetsutohagane.TETSU-2016-107

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2320/matertrans.M2016291

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1080/09500839.2016.1154200

Language：English   Publishing type：Research paper (scientific journal)  

© 2016 Taylor and Francis. The interactions between dislocations and lath boundaries in Grade 91 steel were observed by an in situ transmission electron microscopy tensile test at 973 K. Dislocations glided slowly and bowed out in a martensite lath interior. The ends of the dislocation were connected to the lath boundaries. In a tempered specimen, the pinning stress caused by the lath boundary was estimated to be >70 MPa with a lath width of 0.4 m. In crept specimens, lath coarsening reduced the pinning effect.

DOI： 10.1080/09500839.2016.1154200

Language：English   Publishing type：Research paper (scientific journal)  

© 2015 Acta Materialia Inc. Published by Elsevier Ltd. We performed the three-dimensional visualization of dislocations through serial sectioning and use of SEM electron channeling contrast (ECC) images for a crept nickel-based alloy. We successfully reconstructed a volume of approximately 7.5 μm3, including dislocation arrangements, by performing calculations based on the continuous tomograms of ECC images. By incorporating the information on crystal orientation obtained by the electron back-scattered diffraction, we verified that the three-dimensional arrangement of dislocations, such as slip plane, was accurately reflected in the three-dimensional volume.

DOI： 10.1016/j.scriptamat.2015.02.001

Language：Japanese  

純ニッケルの極低ひずみ速度クリープの変形機構の解明

Language：Japanese  

オーステナイト系耐熱鋼の局所結晶方位解析によるクリープひずみの評価

Language：Japanese  

SEM/EBSD法によるクリープ変形に伴うGr.92鋼溶接継手の組織変化挙動解析

Language：Japanese  

フェライト系耐熱鋼の低応力クリープ変形挙動

Language：Japanese  

局所方位解析法を用いたフェライト系耐熱鋼溶接熱影響部クリープ弱化要因の特定

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2320/matertrans.M2010405

Language：Japanese  

Three-dimensional Microstructure and High Temperature Strength in ODS 9Cr Ferritic Heat Resistant Steels
Oxide-dispersion-strengthened (ODS) 9Cr ferritic heat resistant steel is a leading candidate for a cladding material used in advanced fast reactor fuels because of its superior radiation resistance and high-temperature strength. In this study, distribution of oxides, which is presumed to be a dominant factor of the high-temperature strength, has been evaluated by three-dimensional (3D) observations using electron tomography. The oxide distribution was classified into two regions, whose number densities were high or low. Dislocation pinning forces caused by the oxides were estimated from the 3D data in each region. A good coincidence was recognized between the force in the low-density region and a threshold stress at which the creep deformation mechanism changes. Therefore, the high temperature deformation behavior of ODS steels is influenced by dislocation motions in the low-density regions of oxides.

DOI： 10.3154/jvs.31.98

Language：English   Publishing type：Research paper (scientific journal)  

The creep behavior in pure aluminum has been investigated by helicoid spring creep tests at strain rates, ε̇, lower than 10-10 s-1 and low temperature ranging from 0.32Tm to 0.43T m. It was found that the creep behavior in this region depends strongly on grain sizes and impurity concentrations. For high-purity aluminum (5 N Al) with an average grain size, dg > 1600 μm, nearly the wire diameter of the spring sample, where the role of grain boundary during creep deformation can be negligible, the stress exponent was n ∼ 5 and the activation energy was Qc = 32 kJ/mol. Microstructural observation showed the formation of large dislocation cells (∼10μm) and tangled dislocations at the cell walls. For high-purity aluminum (5N Al) with d g = 24 μm, the stress exponent was n ∼ 1 and the activation energy was Qc = 15kJ/mol. On the other hand, for commercial low-purity aluminum (2 N Al) with dg = 25 μm, the stress exponent was n = 2 and the activation energy was Qc = 25 kJ/mol. Microstructural observations revealed dislocations emitted from grain boundaries, those dislocations interacting with intragranular dislocations and the formation of dislocation cells in the grains. Based on those experimental results, the low-temperature creep mechanisms in pure aluminum at ε̇ < 10-10 s-l have been discussed. © 2011 The Japan Institute of Metals.

DOI： 10.2320/matertrans.M2010405

Language：Japanese  

コイルばねクリープ試験法による改良9Cr‐1Mo鋼の極低速クリープ挙動評価

Language：Japanese  

Pt系分散強化合金の低応力領域でのクリープ特性の検討

Language：Japanese  

コイルばねクリープ試験法による高Cr鋼の低速クリープ挙動評価

Language：Japanese  

コイルばねクリープ試験法によるSUS304鋼のクリープ挙動解析

Venue：弘前大学  

Venue：千葉工業大学  

Venue：千葉工業大学  

Venue：マレーシア工科大学   Country：Malaysia  

Venue：東京工業大学  

Venue：ニューウェルシティ宮崎  

Venue：サンヒルズ三河湾  

Venue：サンヒルズ三河湾  

Venue：サンヒルズ三河湾  

Venue：北海道大学  

Venue：北海道大学  

Venue：北海道大学  

Venue：北海道大学  

Venue：京都大学   Country：Japan  

Venue：東京工業大学  

Venue：熊本大学  

Venue：熊本大学  

Venue：熊本大学  

Venue：北九州国際会議場  

Venue：北九州国際会議場  

Venue：オハイオ州立大  

Venue：IHI 横浜事業所  

Venue：ホテル春慶屋  

Venue：ホテル春慶屋  

Venue：東北大学  

Venue：東北大学  

Venue：東北大学  

Venue：東北大学  

Venue：淡路 ゆうなぎ荘  

Venue：富山国際会議場  

Venue：熊本県民交流館パレア  

Venue：熊本県民交流館パレア  

Venue：Nantes, France  

Venue：東京大学 駒場キャンパス  

Venue：石川県青少年総合研修センター  

Venue：岡山大学  

Venue：Nagasaki Brick Hall  

Venue：レクトーレ箱根強羅  

Venue：東京農工大学 小金井キャンパス  

Venue：東京農工大学 小金井キャンパス  

Venue：Nagasaki Brick Hall  

Venue：Kyushu University  

Venue：岡山大学  

Venue：岡山大学  

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：6

Number of peer-reviewed articles in Japanese journals：2

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：4

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：3

Type：Competition, symposium, etc. 

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：2

Number of peer-reviewed articles in Japanese journals：1

Proceedings of International Conference Number of peer-reviewed papers：0

Proceedings of domestic conference Number of peer-reviewed papers：0

Type：Competition, symposium, etc.