Crystallographic microstructure study of a japanese sword made by noritsuna in the muromachi period by pulsed neutron bragg-edge transmission imaging

Abstract

Large-area real-space distribution of crystallographic microstructural information in a Japanese sword made by Noritsuna at Bizen in A.D. 1405 was non-destructively investigated by Bragg-edge neutron transmission imaging using the RADEN instrument at BL22 of MLF (Materials and Life Science Experimental Facility) in J-PARC and the data analysis software RITS (Rietveld Imaging of Transmission Spectra), as one of the series of a systematic research project. As a result, unique properties of the Noritsuna sword were revealed as follows. Hard martensite which d-spacing is close to that of a modern quenched steel exists at the cutting edge, but the area is smaller than that of a modern sword. Coarse grains exist near the notch at the back of the tang. Fine and coarse crystallite-size steels are separately distributed. The texture is not so strong, and the preferred orientation <210> is perpendicular to the normal direction of the sword plate except for the front region of the tang region.