精密構造解析による階層異方性ナノ構造合金の超高サイクル疲労強度発見機構の解明
キーワード：疲労, 階層異方性, 高サイクル, 精密構造解析, マグネシウム合金
2022.04～2025.03.

超高強度Mg-Gd-Y-Zn-Zr合金の疲労特性に関する基礎研究
キーワード：Mg合金　疲労 き裂
2022.11～2024.11.

チタン酸ビスマス高温圧電セラミックのドメイン構造と分極ダイナミクス
キーワード：チタン酸ビスマス　圧電セラミック　疲労　ドメイン構造 分極ダイナミクス
2021.08～2023.07.

準安定構造を持つチタン合金のき裂発生および伝ぱ挙動の解明
キーワード：チタン合金　超高サイクル　疲労　き裂伝ぱ
2020.08～2022.07.

チタン合金の超高サイクル疲労および下限界疲労き裂伝ぱ特性の解明
キーワード：チタン合金　超高サイクル　疲労　き裂伝ぱ
2019.05～2021.04.

チタン合金の力学および疲労特性に及ぼす電子ビーム溶接の影響に関する研究
キーワード：力学特性、疲労、チタン合金、微小き裂、き裂発生、き裂伝播、破壊
2018.10～2021.03.

軽量超高強度マグネシウム合金の超高サイクル疲労特性に関する研究
キーワード：疲労、マグネシウム合金、微小き裂、き裂発生、き裂伝播、破壊
2016.04～2019.03.

パリレンC薄膜の力学特性
キーワード：パリレン C、薄膜、力学特性、寸法効果
2016.04.

超高強度Mg-Gd-Y-Zn-Zr合金の疲労特性に関する基礎研究
2022.11～2024.11, 代表者：陳強　, 九州大学, JSPS
The proposed research is to undertake quasi-in situ fatigue observation to characterize fatigue transitions from a crack-free stage to a cracked stage, and further short crack growth stage. This study aims at revealing dislocation structures associated with nucleation of microcracks and connecting atomic scale deformation with macroscopic fatigue performance..

Bismuth titanate-based high temperature piezoceramics: domain structure and polarization dynamics
2021.11～2023.11, 代表者：陳強　, 九州大学, JSPS
代表的な高温用ビスマス層状強誘電体 Bi4Ti3O12に対し、圧電応答顕微鏡(PFM)観察および第一原理計算により強誘電ドメインの微細構造解析を行い、分極特性劣化のメカニズムを解明する。.

Characterization of Crack Nucleation in Titanium Alloys with Metastable Microstructures
2020.08～2022.07, 代表者：陳強　, 九州大学, JSPS
チタン合金の超高サイクル疲労き裂の発生および伝ぱ挙動に着目し、そのき裂発生のメカニズムに及ぼす準安定構造の影響を明らかにする。.

Ultra-high Cycle Fatigue Characterization and Ultra-slow Crack Growth of Titanium Alloys
2019.04～2022.03, 代表者：陳強, 九州大学, JSPS
This project aims to investigate the ultra-high cycle fatigue (UHCF) properties and failure mechanism of titanium alloys, which has found increasing structural applications in ultra-long fatigue life regime. Crack initiation and ultra-slow crack growth behavior will be deeply studied. UHCF strength of titanium alloys will be determined by fatigue tests. Based on atomic characterization technology, fatigue crack initiation mechanism and small crack propagation behavior will be expounded. According to the obtained fatigue failure mechanism, a physically-based prediction model will be proposed to estimate the UHCF life of the alloys. Finally, optimization technique to enhance fatigue strength of titanium alloys will be discussed..

主要原著論文

1.	X. H. Shao, C. He, H. Q. Liu, N. Su, Y. J. Wu, Q. Chen, X. L. Ma, Amorphization of nano-Mg layers in LPSO-containing magnesium alloy during cyclic deformation, Scripta Materialia, 10.1016/j.scriptamat.2024.116059, 245, 2024.05, Microstructural evolution during fatigue is of significance for understanding the fatigue cracking of metallic alloys. Here, we visualized amorphization near the fatigue facets for an Mg-Gd-Y-Zn-Zr alloy with long-period stacking ordered (LPSO) phase upon very high cycle fatigue (VHCF). The small amorphous patches occurred in the relatively soft nano-Mg layers, compared to the hard LPSO phase, and the amorphous band propagated along with the basal plane near the LPSO/Mg interface. This should be intimately related to the local dislocation accumulation and cumulative damage upon the cycle loading-unloading..
2.	Shaoxiong Xie, Qian Xu, Qiang Chen, Jianguo Zhu, Qingyuan Wang, Realizing super-high piezoelectricity and excellent fatigue resistance in domain-engineered bismuth titanate ferroelectrics, advanced functional materials, 2024.02.
3.	Yao Chen, Qi Shuai, Yujuan Wu, Liming Peng, Xiaohong Shao, Fulin Liu, Chao He, Lang Li, Yongjie Liu, Qingyuan Wang, Shaoxiong Xie, Qiang Chen, Fatigue-induced oxidation assisting microcrack nucleation in Mg-RE alloy under ultrasonic fatigue, Scripta Materialia, 10.1016/j.scriptamat.2023.115643, 236, 2023.11, Characterizing the transition from a crack-free to a cracked state remains a challenging topic in fatigue. Mg-rare earth alloys, containing the long-period stacking ordered (LPSO) phase, exhibit superior mechanical properties. Here, microcracks are found to nucleate at the soft α-Mg nano-layers, away from the LPSO lamellae. Notably, severe oxidation is observed along the damage bands. Based on the detailed characterizations, it is suggested that dislocation motions continuously bring the new α-Mg matrix to oxidation transformation, resulting in the thickening MgO layer. However, once the fatigue-induced oxide reaches a certain thickness, it starts acting as a barrier for the further dislocation motions. As a result, dislocation accumulation and cumulative damage occur in the region ahead of the thick oxide, causing microcrack nucleation. This fatigue-induced oxidation, assisting microcrack nucleation, is distinct from the existing fatigue mechanisms..
4.	Yao Chen, Qi Shuai, Yujuan Wu, Liming Peng, Xiaohong Shao, Fulin Liu, Chao He, Lang Li, Yongjie Liu, Qingyuan Wang, Shaoxiong Xie, Qiang Chen, Oxide nodule assisting fatigue crack initiation in hierarchical anisotropic nanostructured Mg-RE alloy, International Journal of Fatigue, 10.1016/j.ijfatigue.2023.107820, 175, 2023.10, Hierarchical anisotropic nanostructured Mg-RE alloys, containing LPSO lamellae and dense nano-precipitates, exhibit superior mechanical properties. However, their reliability as structural materials for long-term service, especially in terms of fatigue, is still a matter of concern. Here, scattered oxide nodules are detected as a special kind of fatigue damage that assists crack initiation, rather than the typical slip-band structure. The LPSO lamellae and dense β′ nano-precipitates lead to the high localization of fatigue damage. The fatigue-induced oxide nodules form and grow within the soft α-Mg layer, but their growth is limited by the adjacent strong LPSO lamellae, resulting in microcrack nucleation. Finally, clusters of microcracks along the LPSO/oxide interface converge to form the trans-granular crack initiation..
5.	Jun Song, Hanqing Liu, Jie Cui, Yongjie Liu, Lang Li, Yao Chen, Qingyuan Wang, Qiang Chen, Crack initiation and short crack propagation of friction stir welded TC17 alloy joint, International Journal of Fatigue, 10.1016/j.ijfatigue.2022.107426, 168, 2023.03, Heterogeneities of microstructure, tensile and fatigue behavior of FSWed titanium alloy joint were in-situ studied by utilizing replica, DIC and electron back-scattered diffraction methods. Banded TMAZ consisting of needle-like α precipitates and elongated αp within DRXed β grains bridges the HAZ and SZ. Fine β grains in SZ contribute to the highest tensile strength in the 3rd layer. Fatigue cracks prefer to nucleate from HAGBs and {1 1 2} 〈1 1 1〉 slip deformation of β structure in the 2nd layer of SZ below 210 MPa and 3rd layer of HAZ otherwise. Transgranular crack propagation along the {1 1 2} planes exhibits a higher crack growth rate in HAZ than SZ..
6.	Shaoxiong Xie, Jikai Shi, Qian Xu, Qingyuan Wang, Jianguo Zhu, Yukio Sato, Qiang Chen, In-depth understanding of {110}-type domain walls in bismuth titanate ceramics, Scripta Materialia, 10.1016/j.scriptamat.2022.114793, 217, 2022.08, Bismuth titanate(BIT) ceramics have been widely studied for high temperature applications thanks to their high Curie temperature and large spontaneous polarization. The underlying domain structures play significant roles in regulating the macroscopic properties of ferroelectric materials, while there is only limited knowledge of the domain structures for BIT ceramics until now, substantially bad for the development of BIT-based new materials. In this study, the intriguing domain walls(DWs) in BIT ceramics were investigated in detail. The atomic-scale observation reveals that there primarily exist energetically favorable {110}-type 90° DWs in BIT ceramics. Combined with the theoretical analysis, these DWs are not only elaborated under multiple piezoelectric response modes, but also further corroborated by the quantitative reconstruction of spatial polarization distributions of twin-related ferroelectric variants. This work sheds insight into domain structure and piezoelectric response mechanism in BIT ceramics, and contributes to promoting their more applications in advanced electron devices..
7.	Hanqing Liu, Jun Song, Xiaojian Cao, Luopeng Xu, Yaohan Du, Lang Li, Qingyuan Wang, Qiang Chen, Enhancement of fatigue resistance by direct aging treatment in electron beam welded Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy joint, Materials Science and Engineering: A, 10.1016/j.msea.2021.142168, 829, 142168-142168, 2022.01.
8.	Hanqing Liu, Jun Song, Haomin Wang, Chuanli Yu, Yaohan Du, Chao He, Qingyuan Wang, Qiang Chen, Slip-driven and weld pore assisted fatigue crack nucleation in electron beam welded TC17 titanium alloy joint, International Journal of Fatigue, 10.1016/j.ijfatigue.2021.106525, 154, 106525-106525, 2022.01.

主要総説, 論評, 解説, 書評, 報告書等

主要学会発表等

所属学会名

学会大会・会議・シンポジウム等における役割

学術論文等の審査

海外渡航状況, 海外での教育研究歴

外国人研究者等の受入れ状況