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：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

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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Publishing type：Research paper (scientific journal)  

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  

DOI： 10.1016/j.scriptamat.2023.115603

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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

Publishing type：Research paper (scientific journal)  

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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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)  

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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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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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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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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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：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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CiNii Research

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：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：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)  

DOI： 10.1016/j.jallcom.2021.161154

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DOI： 10.2355/tetsutohagane.TETSU-2021-069

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

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

DOI： 10.1016/j.scriptamat.2021.113895

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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

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DOI： 10.1016/j.mtcomm.2021.102041

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DOI： 10.1021/acsaelm.0c00902

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DOI： 10.2355/tetsutohagane.TETSU-2020-041

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DOI： 10.2464/JILM.70.405

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

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

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DOI： 10.1016/j.mtla.2020.100716

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DOI： 10.1016/j.actamat.2020.04.051

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DOI： 10.1016/j.matchar.2020.110282

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© 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

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DOI： 10.1093/jmicro/dfaa002

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

DOI： 10.1016/j.ijplas.2019.12.001

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DOI： 10.3390/met9040468

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

DOI： 10.1021/acsnano.8b03055

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DOI： 10.1021/acsnano.8b03055

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DOI： 10.2320/jinstmet.J2017025

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

DOI： 10.2320/jinstmet.J2017025

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DOI： 10.1016/j.matchar.2017.04.010

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

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)  

DOI： 10.1080/09500839.2016.1154200

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

DOI： 10.1016/j.scriptamat.2015.02.001

Language：Japanese  

Language：Japanese  

Language：Japanese  

Language：Japanese  

Language：Japanese  

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

DOI： 10.2320/matertrans.M2010405

Language：Japanese  

高速増殖炉内燃料被覆管の候補材料として研究開発が行われている酸化物分散強化(ODS)型9Crフェライト系耐熱鋼について，内部に生成するイットリア系酸化物の分散状態を電子線トモグラフィーにより3次元的に評価した．酸化物は，高密度な領域と低密度な領域が鋼管の押出し方向と平行になるように積層した分布を持っていた．それぞれの領域で，酸化物による変形への抵抗力を粒径や粒子間距離などから算出すると，700℃において，高密度領域では232～278MPa，低密度領域では154～184MPaであった．さらに，クリープ特性を評価したところ，約140MPaでクリープ変形機構の遷移が認められた．このしきい値は，低密度領域の酸化物による変形の抵抗力におおよそ一致している．すなわち，低密度に酸化物が分散した領域において転位の運動が速く，このことがODS鋼の高温強度や変形機構に強く影響を及ぼしていると示唆された．

DOI： 10.3154/jvs.31.98

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

DOI： 10.2320/matertrans.M2010405

Language：Japanese  

Language：Japanese  

Language：Japanese  

Language：Japanese  

Venue：弘前大学  

Venue：千葉工業大学  

Venue：千葉工業大学  

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  

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：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：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：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：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.