TENSILE SUPERPLASTIC DEFORMATION OF Yba_2Cu_3O_7-x HIGH-T_C SUPERCONDUCTORS

摘要

The superplastic behavior of polycrystalline Yba_2Cu_3O_7-x was investigated. Tensile elongations above 85/100 were achieved for fine-grained(<1μm)microstructures tested in the temperature range of 800- 875 deg. C and strain rates varying from 6×10~-6 to 10~-3/s. It is suggested that the dominant superplastic defor- mation mechanism is grain boundary sliding accommodated and controlled by interface reaction, characterized by a stress exponent of n=2, a grain size exponent of p=1.5, and an activation energy of Q_sp=515±104 kJ/mol.