EFFECT OF MICROSTRUCTURE ON THE HARDNESS AND FRACTURE-TOUGHNESS OF YBA2CU3O7-X/AG COMPOSITES

Applications of YBa2Cu3O7-x (Y123) superconducting ceramic are often handicapped by the problems associated with its poor mechanical performance. In the present study, silver inclusions were introduced into the Y123 matrix and the effects of microstructure on the hardness and the fracture toughness of the composites were investigated. The results revealed that the hardness of the composites depends strongly on the amount of porosity and the silver content, and that the fracture toughness also depends on the silver content. Both hardness and fracture toughness exhibit a strong dependence on the inter-connectivity of the silver inclusions. As the amount of interconnected silver is increased, the hardness becomes less sensitive to the existence of porosity and the toughness is enhanced. The composites are therefore more tolerant to intrinsic flaws than is the matrix alone.