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neutron diffraction revealing the achievement of excellent combination of strength and ductility in metastable austenitic steel by grain refinementMao, W.; Gong, W.; Harjo, S.; Morooka, Satoshi; Gao, S.*; Kawasaki, Takuro; Tsuji, Nobuhiro*
Journal of Materials Science & Technology, 176, p.69 - 82, 2024/03
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)The yield stress of Fe-24Ni-0.3C (wt.%) metastable austenitic steel increased 3.5 times (158 
551 MPa) when the average grain size decreased from 35 
m (coarse-grained [CG]) to 0.5 m (ultrafine-grained [UFG]), whereas the tensile elongation was kept large (0.87 0.82). neutron diffraction measurements of the CG and UFG Fe-24Ni-0.3C steels were performed during tensile deformation at room temperature to quantitatively elucidate the influence of grain size on the mechanical properties and deformation mechanisms. The initial stages of plastic deformation in the CG and UFG samples were dominated by dislocation slip, with deformation-induced martensitic transformation (DIMT) also occurring in the later stage of deformation. Results show that grain refinement increases the initiation stress of DIMT largely and suppresses the rate of DIMT concerning the strain, which is attributed to the following effects. (i) Grain refinement increased the stabilization of austenite and considerably delayed the initiation of DIMT in the 
111
//LD (LD: loading direction) austenite grains, which were the most stable grains for DIMT. As a result, most of the 111//LD austenite grains in the UFG specimens failed to transform into martensite. (ii) Grain refinement also suppressed the autocatalytic effect of the martensitic transformation. Nevertheless, the DIMT with the low transformation rate in the UFG specimen was more efficient in increasing the flow stress and more appropriate to maintain uniform deformation than that in the CG specimen during deformation. The above phenomena mutually contributed to the excellent combination of strength and ductility of the UFG metastable austenitic steel.
Gong, W.; Gholizadeh, R.*; Kawasaki, Takuro; Aizawa, Kazuya; Harjo, S.
Magnesium Technology 2024, p.89 - 90, 2024/03
neutron diffraction during cryogenic coolingYamashita, Takayuki*; Harjo, S.; Kawasaki, Takuro; Morooka, Satoshi; Gong, W.; Fujii, Hidetoshi*; Tomota, Yo*
ISIJ International, 64(2), p.192 - 201, 2024/01
neutron diffractionZhou, Y.*; Song, W.*; Zhang, F.*; Wu, Y.*; Lei, Z.*; Jiao, M.*; Zhang, X.*; Dong, J.*; Zhang, Y.*; Yang, M.*; et al.
Journal of Alloys and Compounds, 971, p.172635_1 - 172635_7, 2024/01
Times Cited Count：0 Percentile：0(Chemistry, Physical)Harjo, S.; Gong, W.; Kawasaki, Takuro
Quantum Beam Science (Internet), 7(4), p.32_1 - 32_13, 2023/12
Dannoshita, Hiroyuki*; Hasegawa, Hiroshi*; Higuchi, Sho*; Matsuda, Hiroshi*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Umezawa, Osamu*
Scripta Materialia, 236, p.115648_1 - 115648_5, 2023/11
Times Cited Count：0 Percentile：0(Nanoscience & Nanotechnology)
ders band deformation in an ultrafine grain stainless steel by combining neutron diffraction and digital image correlation analysisMao, W.; Gao, S.*; Gong, W.; Harjo, S.; Kawasaki, Takuro; Tsuji, Nobuhiro*
Scripta Materialia, 235, p.115642_1 - 115642_6, 2023/10
Times Cited Count：1 Percentile：0(Nanoscience & Nanotechnology)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.
Mao, W.; Gao, S.*; Gong, W.; Bai, Y.*; Harjo, S.; Park, M.-H.*; Shibata, Akinobu*; Tsuji, Nobuhiro*
Acta Materialia, 256, p.119139_1 - 119139_16, 2023/09
Times Cited Count：5 Percentile：90.35(Materials Science, Multidisciplinary)Transformation-induced plasticity (TRIP)-assisted steels exhibit an excellent combination of strength and ductility due to enhanced strain hardening rate associated with deformation-induced martensitic transformation (DIMT). Quantitative evaluation on the role of DIMT in strain hardening behavior of TRIP-assisted steels and alloys can provide guidance for designing advanced materials with strength and ductility synergy, which is, however, difficult since the phase composition keeps changing and both stress and plastic strain are dynamically partitioned among constituent phases during deformation. In the present study, tensile deformation with neutron diffraction measurement was performed on an Fe-24Ni-0.3C (wt.%) TRIP-assisted austenitic steel. The analysis method based on stress partitioning and phase fractions measured by neutron diffraction was proposed, by which the tensile flow stress and the strain hardening rate of the specimen were resolved into factors associated with each phase, i.e., the austenite matrix, deformation-induced martensite, and the transformation rate of DIMT after differentiation, and then the role of each factor in the global strain hardening behavior was discussed. In addition, the plastic strain partitioning between austenite and martensite was indirectly estimated using the dislocation density measured by diffraction profile analysis, which constructed the full picture of stress and strain partitioning between austenite and martensite in the material. The results suggested that both the transformation rate and the phase stress borne by the deformation-induced martensite played important roles in the global tensile properties of the material. The proposed decomposition analysis method could be widely applied to investigating mechanical behavior of multi-phase alloys exhibiting the TRIP phenomenon.
Mg and long-period stacking ordered phases in a Mg-Zn-Y alloy by hot-extrusion with low extrusion ratioHarjo, S.; Gong, W.; Aizawa, Kazuya; Kawasaki, Takuro; Yamasaki, Michiaki*
Acta Materialia, 255, p.119029_1 - 119029_12, 2023/08
Times Cited Count：6 Percentile：95.52(Materials Science, Multidisciplinary) neutron diffraction study on the deformation behavior of the plastic inorganic semiconductor Ag
SWang, Y.*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Zhang, K.*; Zhang, Z. D.*; Li, B.*
Applied Physics Letters, 123(1), p.011903_1 - 011903_6, 2023/07
Times Cited Count：1 Percentile：54.89(Physics, Applied) neutron diffractionGong, W.; Harjo, S.; Tomota, Yo*; Morooka, Satoshi; Kawasaki, Takuro; Shibata, Akinobu*; Tsuji, Nobuhiro*
Acta Materialia, 250, p.118860_1 - 118860_16, 2023/05
Times Cited Count：2 Percentile：74.65(Materials Science, Multidisciplinary)Kwon, H.*; Sathiyamoorthi, P.*; Gangaraju, M. K.*; Zargaran, A.*; Wang, J.*; Heo, Y.-U.*; Harjo, S.; Gong, W.; Lee, B.-J.*; Kim, H. S.*
Acta Materialia, 248, p.118810_1 - 118810_12, 2023/04
Times Cited Count：13 Percentile：99.28(Materials Science, Multidisciplinary)Wang, Y.*; Tomota, Yo*; Omura, Takahito*; Gong, W.; Harjo, S.
Materialia, 27, p.101685_1 - 101685_9, 2023/03
Nishida, Masayuki*; Harjo, S.; Kawasaki, Takuro; Yamashita, Takayuki*; Gong, W.
Quantum Beam Science (Internet), 7(1), p.8_1 - 8_15, 2023/03
neutron diffraction studyGong, W.; Kawasaki, Takuro; Zheng, R.*; Mayama, Tsuyoshi*; Sun, B.*; Aizawa, Kazuya; Harjo, S.; Tsuji, Nobuhiro*
Scripta Materialia, 225, p.115161_1 - 115161_5, 2023/03
Times Cited Count：4 Percentile：45.58(Nanoscience & Nanotechnology)Mg/LPSO dual-phase magnesium alloy monitored by neutron diffractionHarjo, S.; Gong, W.; Aizawa, Kazuya; Kawasaki, Takuro; Yamasaki, Michiaki*; Mayama, Tsuyoshi*; Kawamura, Yoshihito*
Materials Transactions, 64(4), p.766 - 773, 2023/02
Times Cited Count：4 Percentile：90.35(Materials Science, Multidisciplinary) phase to 
phase in zirconium alloy revealed by in-situ neutron diffraction during high temperature deformationGuo, B.*; Mao, W.; Chong, Y.*; Shibata, Akinobu*; Harjo, S.; Gong, W.; Chen, H.*; Jonas, J. J.*; Tsuji, Nobuhiro*
Acta Materialia, 242, p.118427_1 - 118427_11, 2023/01
Times Cited Count：5 Percentile：64.46(Materials Science, Multidisciplinary)Tsuchida, Noriyuki*; Ueji, Rintaro*; Gong, W.; Kawasaki, Takuro; Harjo, S.
Scripta Materialia, 222, p.115002_1 - 115002_6, 2023/01
Times Cited Count：5 Percentile：64.46(Nanoscience & Nanotechnology)Wei, D.*; Gong, W.; Tsuru, Tomohito; Lobzenko, I.; Li, X.*; Harjo, S.; Kawasaki, Takuro; Do, H.-S.*; Bae, J. W.*; Wagner, C.*; et al.
International Journal of Plasticity, 159, p.103443_1 - 103443_18, 2022/12
Times Cited Count：27 Percentile：98.49(Engineering, Mechanical) observation of twinning and detwinning in AZ31 alloyGong, W.; Zheng, R.*; Harjo, S.; Kawasaki, Takuro; Aizawa, Kazuya; Tsuji, Nobuhiro*
Journal of Magnesium and Alloys (Internet), 10(12), p.3418 - 3432, 2022/12
Times Cited Count：17 Percentile：93.62(Metallurgy & Metallurgical Engineering)