Revealing deformation mechanism of fine-grained Mg alloys via neutron diffraction analysis

Somekawa, Hidetoshi*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Singh, A.*; Tomota, Yo*

Scripta Materialia, 269, p.116921_1 - 116921_6, 2025/12

https://doi.org/10.1016/j.scriptamat.2025.116921

Revisiting hydrogen trapping in Mg(Al, Zn) Approximant crystal; Influence of chemical disorder

Shimizu, Kazuyuki*; Yamaguchi, Masatake; Akamaru, Satoshi*; Nishimura, Katsuhiko*; Abe, Rion*; Sasaki, Taisuke*; Wang, Y.*; Toda, Hiroyuki*

Scripta Materialia, 265, p.116730_1 - 116730_7, 2025/08

https://doi.org/10.1016/j.scriptamat.2025.116730

Unique deformation behavior of ultrafine-grained 304 stainless steel at 20 K

Mao, W.*; Gong, W.; Kawasaki, Takuro; Gao, S.*; Ito, Tatsuya; Yamashita, Takayuki*; Harjo, S.; Zhao, L.*; Wang, Q.*

Scripta Materialia, 264, p.116726_1 - 116726_6, 2025/07

https://doi.org/10.1016/j.scriptamat.2025.116726

Anomalous dislocation response to deformation strain in CrFeCoNiPd high-entropy alloys with nanoscale chemical fluctuations

Ying, H.*; Yang, X.*; He, H.*; Yan, A.*; An, K.*; Ke, Y.*; Wu, Z.*; Tang, S.*; Zhang, Z.*; Dong, H.*; et al.

Scripta Materialia, 250, p.116181_1 - 116181_7, 2024/09

https://doi.org/10.1016/j.scriptamat.2024.116181

Control of twin boundary mobility by solute segregation in Mg binary alloys

Somekawa, Hidetoshi*; Tsuru, Tomohito; Naito, Kimiyoshi*; Singh, A.*

Scripta Materialia, 249, p.116173_1 - 116173_6, 2024/08

https://doi.org/10.1016/j.scriptamat.2024.116173

The segregated twin boundaries play a role in obstruction of dislocation slips. Thus, they contribute to increase in hardness. Internal friction tests reveal that, irrespective of the solute elements, induced twin boundaries are effective in enhancing damping capacity, owing to their reversible motion, i.e., growth and shrinkage. In contrast, by comparison of the loss factor of specimens with/without twin boundary segregation, segregation leads to a decrease in damping capacity. The energy barrier required for twin boundary sliding to occur is closely related to the loss factor.

Stress corrosion cracking induced by the combination of external and internal hydrogen in Al-Zn-Mg-Cu alloy

Tang, J.*; Wang, Y.*; Fujihara, Hiro*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*; Ebihara, Kenichi; Takeuchi, Akihisa*; Uesugi, Masayuki*; Toda, Hiroyuki*

Scripta Materialia, 239, p.115804_1 - 115804_5, 2024/01

https://doi.org/10.1016/j.scriptamat.2023.115804

Stress corrosion cracking (SCC) behaviors induced by the combination of external and internal hydrogen (H) in an Al-Zn-Mg-Cu alloy were systematically investigated via in situ 3D characterization techniques. SCC of the Al-Zn-Mg-Cu alloy could initiate and propagate in the potential crack region where the H concentration exceeded a critical value, in which the nanoscopic H-induced decohesion of -MgZn precipitates resulted in macroscopic cracking. External H that penetrated the alloy from the environment played a crucial role during the SCC of the Al-Zn-Mg-Cu alloy by generating gradient-distributed H-affected zones near the crack tips, which made Al alloys in water environment more sensitive to SCC. Additionally, the pre-existing internal H was driven toward the crack tips during plastic deformation. It was involved in the SCC and made contributions to both the cracks initiation and propagation.

Quantitatively evaluating the huge Lders band deformation in an ultrafine grain stainless steel by combining neutron diffraction and digital image correlation analysis

Mao, W.; Gao, S.*; Gong, W.; Harjo, S.; Kawasaki, Takuro; Tsuji, Nobuhiro*

Scripta Materialia, 235, p.115642_1 - 115642_6, 2023/10

https://doi.org/10.1016/j.scriptamat.2023.115642

In the present study, a hybrid neutron diffraction and digital image correlation measurement was performed on tensile deformation of an ultrafine grain (UFG) stainless steel exhibiting a huge Lders band deformation to evaluate the individual contribution of the austenite matrix and the deformation-induced martensite to the strain hardening during the propagation of the band. Quantitative analysis revealed that the strain hardening of the austenite matrix was insufficient to maintain a uniform deformation when the flow stress was greatly enhanced by the UFG structure. The strain hardening required for the Lders band to propagate was mostly provided by the formation of martensite and the high internal stress within it.

Stress partitioning between bcc and cementite phases discussed from phase stress and dislocation density in martensite steels

Tsuchida, Noriyuki*; Ueji, Rintaro*; Gong, W.; Kawasaki, Takuro; Harjo, S.

Scripta Materialia, 222, p.115002_1 - 115002_6, 2023/01

https://doi.org/10.1016/j.scriptamat.2022.115002

Comparative study of stress and strain partitioning behaviors in medium manganese and transformation-induced plasticity-aided bainitic ferrite steels

Hojo, Tomohiko*; Koyama, Motomichi*; Kumai, Bakuya*; Shibayama, Yuki; Shiro, Ayumi*; Shobu, Takahisa; Saito, Hiroyuki*; Ajito, Saya*; Akiyama, Eiji*

Scripta Materialia, 210, p.114463_1 - 114463_5, 2022/03

https://doi.org/10.1016/j.scriptamat.2021.114463

Artificial neural network molecular mechanics of iron grain boundaries

Shiihara, Yoshinori*; Kanazawa, Ryosuke*; Matsunaka, Daisuke*; Lobzenko, I.; Tsuru, Tomohito; Koyama, Masanori*; Mori, Hideki*

Scripta Materialia, 207, p.114268_1 - 114268_4, 2022/01

https://doi.org/10.1016/j.scriptamat.2021.114268

This study reports grain boundary (GB) energy calculations for 46 symmetric-tilt GBs in -iron using molecular mechanics based on an artificial neural network (ANN) potential and compares the results with calculations based on the density functional theory (DFT), the embedded atom method (EAM), and the modified EAM (MEAM). The results by the ANN potential are in excellent agreement with those of the DFT (5% on average), while the EAM and MEAM significantly differ from the DFT results (about 27% on average). In a uniaxial tensile calculation of GB, the ANN potential reproduced the brittle fracture tendency of the GB observed in the DFT while the EAM and MEAM mistakenly showed ductile behaviors. These results demonstrate the effectiveness of the ANN potential in calculating grain boundaries of iron, which is in high demand in modern industry.