Archaeometallurgy study of Japanese sword using neutron diffraction

中性子回折を用いた日本刀の古冶金学的研究

Harjo, S.   ; 及川 健一   ; 川崎 卓郎   ; Grazzi, F.*; 篠原 武尚   ; 田中 眞奈子*; Pham, A.*; 森戸 茂一*; 鬼柳 善明*; 伊藤 正和*

Harjo, S.; Oikawa, Kenichi; Kawasaki, Takuro; Grazzi, F.*; Shinohara, Takenao; Tanaka, Manako*; Pham, A.*; Morito, Shigekazu*; Kiyanagi, Yoshiaki*; Ito, Masakazu*

We used neutron diffraction mapping measurements to elucidate the Japanese sword's microstructure and discuss the manufacturing procedures. Mapping measurements using pulsed neutron diffraction with time-of-flight method were performed on a full-shape and test pieces of Japanese sword. The obtained diffraction patterns are analyzed by the Rietveld refinement and a line profile analysis. The constituent phases in the area closer to the back of the blade (ridge) are found to be ferrite and cementite, composing pearlite, while the area close to the edge is composed by martensite and austenite. The distributions of constituent phases are well explained with the distributions of dislocation density and crystallite size.