Internal strain measurement in superconducting composites by neutron diffraction

Harjo, S.   ; Aizawa, Kazuya  ; Ito, Takayoshi*; Abe, Jun; Osamura, Kozo*; Hemmi, Tsutomu; Jin, X.*; Nakamoto, Tatsushi*; Awaji, Satoshi*; Takahashi, Koki*

Phase strains are always generated in the superconducting composites, due to differences on thermal expansion and deformability among the constituent phases. In contrast, internal strain state has high influences on superconducting properties, e.g. the presence of internal strain degrades critical current densities. Therefore, clarifying internal strains behaviors accurately will help us to develop superconducting composites having optimum superconducting performances during uses. However, the internal strains in superconducting composites have not been measured so far because of the composites configurations. Neutrons that have high penetration ability into metals may be a powerful tool to measure internal strains in the superconducting composites by the diffraction technique. Here, we introduce internal strain measurement techniques, our engineering materials diffractometer at J-PARC facility and our trials on measuring internal strains in several kinds of superconducting composites.