Deformation and fracture behavior of Sm123 bulk superconductors by compressive loading at room temperature

In order to investigate the compressive mechanical characteristics of Sm123 single-grain bulk superconductors fabricated by TSMG method, compressive tests in the direction parallel and perpendicular to the c-axis have been carried out by using small specimens cut from the bulk samples. Stress-strain curves in the direction perpendicular to the c-axis were almost linear. The Young´s moduli measured were 155-165 GPa. In the case of loading parallel to the c-axis, the curves were exponential in the low stress region. As the stress increased, they tended to a linear relation. The apparent Young´s modulus in this region was 75-110 GPa. These characteristics are mainly ascribed to the closure behavior of pre-existing micro-cracks perpendicular to the c-axis. The average fracture strength in the direction of c-axis, 350-400 MPa, was larger than that perpendicular to it, 235-275 MPa. Specimens in the former were generally broken into great many small pieces while those in the latter were broken into some parts by lateral cracking. The compressive Young´s modulus and the fracture strength for each direction were higher than those evaluated by the tensile loading, respectively. The effects of specimen length on the compressive mechanical properties were also discussed.