Young’s modulus of polycrystalline Nb3Sn between 4.2 and 300 K

摘要: Ultrasonic measurements show that the shear modulus 1/2 (C11−C12) softens dramatically as single crystals of Nb3Sn approach martensitic transition near 50 K. It is expected Young’s polycrystals will also soften, but previous ultrasonic measurements, which suffer from severe damping, fail to effect. We have measured Modulus polycrystalline between 4.2 and 300 K by static beam‐deflection methods observe marked softening. A value 1.32×1012 dyn cm−2 was obtained at deflection thin Nb3Sn‐Nb‐Nb3Sn composite strips external stress. The variation with T change in radius curvature internally stressed Nb3Sn‐Nb strips. (This method made possible near‐perfect match thermal expansion coefficients Nb Nb3Sn.) found be proportional lnT temperature independent below superconducting Tc, resulting a decre...