Annealing and mechanical properties of bulk Y-Ba-Cu-O

Melt-processed YBa(2)Cu(3)O(x)/Y(2)BaCuO(5) and conventional polycrystalline sintered YBa(2)Cu(3)O(x) pellets were prepared. Elastic modulus, hardness, and fracture strength were measured on selected selections cut from the pellets. Strength in the melt-processed pellets ranged from 32 to 94 MPa and was highest in the center. Variations in strength were related to microstructural features, especially Y(2)BaCuO(5) distribution. To improve strength, we attempted to minimize microcracking by manipulating cooling rates and annealing times. We found that control of annealing reduced microcracking of the polycrystalline sintered pellets, but had little effect on the single-domain melt-processed pellets.