From Koto age to modern times: Quantitative characterization of Japanese swords with time of flight neutron diffraction

Japanese blades have always been considered very interesting objects, both from the stylistic point of view and their peculiar performances. It is amazing how the test and try process with a semi-empirical approach which lead to the optimization of Japanese blades, an almost ideal tool, is yet to be fully understood. In this work, we present results from a new non invasive approach to the study of these peculiar artefacts. Time of Flight Thermal Neutron Diffraction (TOF-ND) measurements were taken on two instrument INES and ENGIN-X, at the ISIS facility, RAL, UK. Two Japanese blades and eight blade fragments have been successfully characterized in terms of composition of the steel, smelting and smithing processes, and forging techniques. The differences among the production periods and forging traditions have been clearly determined. Further work is needed on standards to fully understand the production technique of a sample by comparison of the object under study with objects of known production methods.