Nondestructive analysis of internal crystallographic structures of Japanese swords using neutron imaging

Matsumoto, Yoshihiro*; Oikawa, Kenichi   ; Watanabe, Kenichi*; Sato, Hirotaka*; Parker, J. D.*; Shinohara, Takenao   ; Kiyanagi, Yoshiaki*

We investigated the internal crystallographic structures of Japanese swords using a nondestructive analysis method that combines neutron Bragg-edge transmission (BET) imaging and neutron tomography. BET provides insights into the crystalline structure of the steel, while the neutron tomography offers cross-sectional views of the sword. To systematically explore and understand the technical and historical transition of Japanese sword-making methods, it is important to analyze the internal crystalline structure of various swords, taking into account factors such as production period, region, and swordsmith. Our study examined three swords: Kashu Kiyomitsu, Nankaitaro Tomotaka, and Hosokawa Masanori. The results reveal distinct differences in the internal structures of these swords. This innovative nondestructive approach allowed us to gain detailed insights into the microstructures of these historical artifacts without causing any damage.