Refine your search:     
Report No.
 - 
Search Results: Records 1-15 displayed on this page of 15
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Investigation of elastic deformation mechanism in as-cast and annealed eutectic and hypoeutectic Zr-Cu-Al metallic glasses by multiscale strain analysis

Suzuki, Hiroshi; Yamada, Rui*; Tsubaki, Shinki*; Imafuku, Muneyuki*; Sato, Shigeo*; Watanuki, Tetsu; Machida, Akihiko; Saida, Junji*

Metals, 6(1), p.12_1 - 12_11, 2016/01

 Times Cited Count:3 Percentile:23.78(Materials Science, Multidisciplinary)

Elastic deformation behaviors of as-cast and annealed eutectic and hypoeutectic Zr-Cu-Al bulk metallic glasses (BMGs) were investigated on a basis of different strain-scales determined by X-ray scattering and the strain gauge. The microscopic strains determined by Direct-space method (DSM) and Q-space method (QSM) were compared with the macroscopic strain measured by the strain gauge, and the difference in the deformation mechanism between eutectic and hypoeutectic Zr-Cu-Al BMGs was investigated by their correlation. The eutectic Zr$$_{50}$$Cu$$_{40}$$Al$$_{10}$$ BMG obtains more homogeneous microstructure by free-volume annihilation after annealing, improving a resistance to deformation but degrading ductility because of a decrease in the volume fraction of WBRs (Weakly-Bonded Regions) with relatively high mobility. On the other hand, the as-cast hypoeutectic Zr$$_{60}$$Cu$$_{30}$$Al$$_{10}$$ BMG originally has homogeneous microstructure, but loses its structural and elastic homogeneities because of nanocluster formation after annealing. Such structural changes after annealing might develop unique mechanical properties showing no degradations of ductility and toughness for the structural-relaxed hypoeutectic BMGs.

Journal Articles

Distribution and anisotropy of dislocations in cold-drawn pearlitic steel wires analyzed using micro-beam X-ray diffraction

Sato, Shigeo*; Shobu, Takahisa; Sato, Kozue*; Ogawa, Hiromi*; Wagatsuma, Kazuaki*; Kumagai, Masayoshi*; Imafuku, Muneyuki*; Tashiro, Hitoshi*; Suzuki, Shigeru*

ISIJ International, 55(7), p.1432 - 1438, 2015/07

 Times Cited Count:9 Percentile:51.23(Metallurgy & Metallurgical Engineering)

To characterize the distribution and anisotropy of dislocations in cold-drawn pearlitic steel wires, X-ray diffraction line-profile analysis was performed using synchrotron radiation micro-beams. The plastic shear strain was generally more severe near the surface than the center of the wire, whereas the dislocation density distribution was almost constant from the center to the surface. On the other hand, the dislocation rearrangement, which evolves the dislocation cell structure, progressed closer to the surface. It was also revealed that a difference between the hardness in axial and transverse wire directions could be explained by anisotropic dislocation density. Line-profile analysis based on diffraction data at elevated temperatures was performed. Whereas the cementite recovery progressed at a constant rate, the ferrite phase recovery rate was temperature-dependent, suggesting that the ferrite phase recovery was less related to that of the cementite phase.

Journal Articles

Internal stress distribution for generating closure domains in laser-irradiated Fe-3%Si(110) steels

Iwata, Keiji*; Imafuku, Muneyuki*; Suzuki, Kanki*; Shobu, Takahisa; Orihara, Hideto*; Sakai, Yusuke*; Akita, Koichi; Oya, Shinichi*; Ishiyama, Kazushi*

Journal of Applied Physics, 117(17), p.17A910_1 - 17A910_4, 2015/03

 Times Cited Count:5 Percentile:27.89(Physics, Applied)

Internal stress distribution for generating closure domains occurring in laser-irradiated Fe-3%Si(110) steels was investigated using high-energy X-ray analysis and domain theory based on the variational principle. The measured triaxial stresses inside the specimen were compressive and the stress in the rolling direction became more dominant than stresses in the other directions. The calculations based on the variational principle of magnetic energy for closure domains showed that the measured triaxial stresses made the closure domains more stable than the basic domain without closure domains. The experimental and calculation results reveal that the laser-introduced internal stresses result in the occurrence of the closure domains.

Journal Articles

X-ray line profile study on shot/laser-peened stainless steel

Kumagai, Masayoshi*; Akita, Koichi; Imafuku, Muneyuki*; Oya, Shinichi*

Advanced Materials Research, 996, p.39 - 44, 2014/08

 Times Cited Count:4 Percentile:92.01

The microstructural features of shot and laser peened austenitic stainless steels were studied using line profile analysis with X-rays. Although both specimens had similar residual stress profiles toward the depth direction, the microstructural features were different not only on the original surfaces of the specimens but also to several micrometers in depth. The dislocation densities of the SP specimen were greater than that of the LP specimen. And the crystallite sizes of the SP specimen were smaller than that of the LP specimen.

Journal Articles

Workhardening and the microstructural characteristics of shot- and laser-peened austenitic stainless steel

Kumagai, Masayoshi*; Akita, Koichi; Imafuku, Muneyuki*; Oya, Shinichi*

Materials Science & Engineering A, 608, p.21 - 24, 2014/07

 Times Cited Count:8 Percentile:46.14(Nanoscience & Nanotechnology)

The mechanical properties of shot- and laser-peened austenitic stainless steels, AISI316, were evaluated via Vickers hardness tests, and the correlation between workhardening and microstructural characteristics were discussed. Dislocation density, which is a microstructural feature, was determined via X-ray line profile analysis. Martensite was generated only by the shot-peening process. A linear relationship is observed between the hardness and the square root of the dislocation density in spite of the martensite formation on the shot-peened specimen. Therefore, the hardness is increased only by workhardening and is not affected by the martensite. We also clarified that a compressive residual stress greater than the original yield strength of the bare material can be induced because of the increase in yield strength caused by workhardening due to dislocation density increase with the peening process.

Journal Articles

X-ray diffraction study on microstructures of shot/laser-peened AISI316 stainless steel

Kumagai, Masayoshi*; Akita, Koichi; Itano, Yuta*; Imafuku, Muneyuki*; Oya, Shinichi*

Journal of Nuclear Materials, 443(1-3), p.107 - 111, 2013/11

 Times Cited Count:22 Percentile:89.1(Materials Science, Multidisciplinary)

Microstructural features of AISI316 stainless steels processed by shot peening (SP) and laser peening (LP) were studied using X-ray diffraction line profile analyses. Both specimens exhibited similar compressive residual stress profiles. Although the number of dislocations was increased and the crystallites were refined with both processes, the dislocation density in the SP specimen was significantly greater than that in the LP specimen. The crystallite size in the SP specimen was one-third that in the LP specimen. The SP process induced martensite transformation. The variations in the microstructural features differed between samples subjected to the two processes. The SP process resulted in a greater variation in the microstructural features in a sample in which residual stresses similar to that induced by the LP process were induced. Thus, the variations in the microstructural features differed depending on the deformation process.

Journal Articles

X-ray diffraction study of peening induced microstructures on austenitic stainless steel

Kumagai, Masayoshi*; Akita, Koichi; Imafuku, Muneyuki*; Oya, Shinichi*

Nihon Zairyo Gakkai Dai-62-Ki Tsujo Sokai, Gakujutsu Koenkai Rombunshu (USB Flash Drive), 2 Pages, 2013/05

Dislocation densities and crystallite sizes in shot- and laser-peened ANSI316 specimens were evaluated by X-ray line profile analysis. The both peened samples had almost the same depth-distributions of residual stress. Even though dislocations were increased and crystallites were refined in both processes, the dislocation density of SP was significantly higher than that of LP and the crystallite size of SP was one-third that of LP. Thus, the states of the microstructure variations were different depending on the nature of deformation process.

Journal Articles

Evaluation of compressive deformation behavior of Zr$$_{55}$$Al$$_{10}$$Ni$$_{5}$$Cu$$_{30}$$ bulk metallic glass containing ZrC particles by synchrotron X-ray diffraction

Suzuki, Hiroshi; Saida, Junji*; Shobu, Takahisa; Katsuyama, Jinya; Kato, Hidemi*; Imafuku, Muneyuki*; Sato, Shigeo*

Scripta Materialia, 66(10), p.801 - 804, 2012/05

 Times Cited Count:6 Percentile:42.67(Nanoscience & Nanotechnology)

Compressive deformation mechanism of a Zr$$_{55}$$Al$$_{10}$$Ni$$_{5}$$Cu$$_{30}$$ bulk metallic glass containing 10vol.%ZrC (ZrC-BMG) was evaluated by measuring the residual strains in the compressive deformed samples using the synchrotron X-ray diffraction and also evaluating the localized deformation behavior around the ZrC particles by the finite element analysis. Phase stress shared by the metallic glass matrix was increased before macroscopic yielding due to local plastic deformation around the ZrC particles. After macroscopic yielding, the phase stress shared by the ZrC phase was drastically increased, and finally the ZrC-BMG was fractured by breaking the ZrC particles reaching its fracture strength.

Oral presentation

Evaluation of deformation behavior on metallic glass by neutron diffraction

Suzuki, Hiroshi; Saida, Junji*; Imafuku, Muneyuki*; Sato, Shigeo*

no journal, , 

Residual stress measurements using neutron and X-ray diffractions are applicable to crystalline materials whereas the strain measurement in amorphous materials had been difficult. Recently, Q-space method, which can evaluate the strain from peak shift of 1st halo peak measured by synchrotron X-ray, and Direct space method, which can evaluate the strain from changes in local structures obtained by the radial distribution function, have been reported by Poulsed et al. In this study, the evaluation of tensile deformation in Zr$$_{55}$$Al$$_{10}$$Ni$$_{5}$$Cu$$_{30}$$ metallic glass using Q-space method was discussed by using neutron diffraction.

Oral presentation

Evaluation of residual stress and deformation behavior on ZrC particulate reinforced metallic glass using neutron diffraction

Suzuki, Hiroshi; Saida, Junji*; Imafuku, Muneyuki*

no journal, , 

Residual stress and deformation behavior on a Zr$$_{55}$$Al$$_{10}$$Ni$$_{5}$$Cu$$_{30}$$ bulk metallic glass containing 10vol%ZrC particles were measured using neutron diffraction. Elastic deformation behavior under uniaxial tensile loading can be predicted by the Self-Consistent model. Since phase stress transferred to the metallic glass matrix is 5% less than applied stresses and the residual stress in the matrix is approximately 100MPa in tension, the compressive strength of the composite bulk metallic glass would be higher than that of monolithic one.

Oral presentation

Measurement of laser induced residual stress of Si-Fe single-crystal using synchrotron X-ray diffraction

Sakai, Yusuke*; Akita, Koichi*; Oya, Shinichi*; Sueyoshi, Kazuyuki*; Shobu, Takahisa; Imafuku, Muneyuki*; Suzuki, Kanki*; Iwata, Keiji*

no journal, , 

no abstracts in English

Oral presentation

Evaluation of deformation behavior on ZrC particle reinforced Zr-Al-Ni-Cu metallic glass using neutron diffraction technique

Suzuki, Hiroshi; Imafuku, Muneyuki*; Saida, Junji*; Setyawan, A. D.*; Kato, Hidemi*

no journal, , 

Deformation behavior on a Zr$$_{55}$$Al$$_{10}$$Ni$$_{5}$$Cu$$_{30}$$ bulk metallic glass containing 10 vol%ZrC particles were measured using neutron diffraction. Elastic deformation behavior under uniaxial tensile loading can be predicted by the Self-Consistent model. Higher strength in compressive deformation in this sample is originated from the thermal tensile residual stresses, and from the phase stresses transferred to the metallic glass matrix which are 5% less than the applied stresses under uniaxial loading.

Oral presentation

Evaluation of compressive deformation behavior of Zr-Al-Ni-Cu balk metallic glass containing ZrC particles by neutron diffraction

Suzuki, Hiroshi; Saida, Junji*; Katsuyama, Jinya; Imafuku, Muneyuki*; Setyawan, A. D.*; Kato, Hidemi*; Sato, Shigeo*

no journal, , 

no abstracts in English

Oral presentation

Evaluation of compressive deformation behavior of Zr-Al-Ni-Cu bulk metallic glass containing ZrC particles by synchrotron X-ray

Suzuki, Hiroshi; Saida, Junji*; Kato, Hidemi*; Sato, Shigeo*; Imafuku, Muneyuki*; Shobu, Takahisa

no journal, , 

no abstracts in English

Oral presentation

Evaluation of microstructures of peening processed austenitic stainless steel using X-ray line profile analysis

Kumagai, Masayoshi*; Akita, Koichi; Imafuku, Muneyuki*; Oya, Shinichi*

no journal, , 

Microstructure and residual stress in shot and laser peened AISI316 stainless steels were evaluated using X-ray line profile analysis and residual stress measurements. Although both specimens exhibited similar compressive residual stress profiles in the depth direction, the hardness and dislocation density on the two specimens were different. The hardness of the SP specimen was greater than that of the LP specimen. And the dislocation density in the SP specimen was greater than that in the LP specimen. Thus, although the residual stress profiles of both SP and LP specimens were similar, the microstructural features in the samples differed.

15 (Records 1-15 displayed on this page)
  • 1