Progress of bulk texture measurement techniques using various neutron sources towards widespread materials evaluation

幅広い材料評価に向けた各種中性子源を用いた集合組織測定技術の進捗

徐 平光   ; 山本 和喜 ; Harjo, S.   ; 菖蒲 敬久  ; 岩本 ちひろ*; 高村 正人*; 大竹 淑恵*; 小貫 祐介*; 佐藤 成男*; Liss, K.-D.*

Xu, P. G.; Yamamoto, Kazuyoshi; Harjo, S.; Shobu, Takahisa; Iwamoto, Chihiro*; Takamura, Masato*; Otake, Yoshie*; Onuki, Yusuke*; Sato, Shigeo*; Liss, K.-D.*

Texture as crystallographic preferred orientation of polycrystalline materials has attracted broad attention due to its important effects on mechanical and physical characteristics. Within both metals and ceramics, widespread applications of texture involve capabilities and simulations in sheet forming, additive manufacturing, while rocks and minerals also demonstrate such feature due to forming processes within the earth. Neutron diffraction can collect high statistical diffractograms due to an excellent penetration and a coarse beam spot, valuable for bulk investigations of microstructural changes and a characteristic response from polycrystalline materials. However, the available neutron instruments are quite limited in the world. We have developed various neutron texture measurement techniques using RESA at JRR-3, TAKUMI and iMATERIA at J-PARC, WOMBAT at ANSTO, and RANS at RIKEN, and obtained the following consensus: for a steady neutron source, the utilization of large area curved detectors together with multiple wavelengths texture analysis technique enables rapid and high precision angle dispersive neutron diffraction measurement; for a pulsed neutron source, the utilization of an optimized detector optical system with proper stereographic angle resolution (2) and instrumental resolution (d/d) is much more valuable for improving the reliability of the time-of-flight neutron diffraction measurement, enabling the orientation feature of tiny amounts of a second phase in a round robin textured limestone sample has been recognized satisfactorily. For a compact neutron source, the selective usage of a high signal-to-noise ratio as well as the wavelength ranges of the time-of-flight neutron diffraction patterns obtained from an in-house texture measurement are effective to reduce the diffraction uncertainty during Rietveld texture analysis, improving instrumental accessibility for on-site applications.