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

Melt-processed YBa2Cu3Ox/Y2BaCuO5 and conventional polycrystalline sintered YBa2Cu3Ox pellets were prepared. Elastic modulus, hardness, and fracture s trength 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 Y2BaCuO5 distribution. To improve strength, we attempted to mi nimize microcracking by manipulating cooling rates and annealing times. We found that control of annealing reduced microcracking of the polycrystallin e sintered pellets, but had little effect on the single-domain melt-process ed pellets.