ANISOTROPIC PLASTIC AND ELASTIC-DEFORMATION IN HIGHLY TEXTURED SUPERCONDUCTING (BI,PB)(2)SR2CA2CU3OX CERAMICS

A highly textured (Bi, Pb)(2)Sr2Ca2Cu3Ox, superconductor has been prep ared and the hardness, deformation and microcracking of the material e xplored using Vickers indentation. The present study has investigated the hardness anisotropy of the highly textured material on cross-secti ons of the specimen which have been chosen to give specific low-index orientations. The hardness was found to decrease as the indentation ro tated from 0 degrees (a diagonal of the indent parallel to the directi on of the texturing) to 45 degrees (the angle between a diagonal of th e indent and the direction of the texturing). The square shape of the indent also changed with rotation from 0 degrees to 45 degrees. The ha rdness anisotropy has been attributed to the influence of elastic and plastic anisotropy in the polycrystalline materials. In addition, a we akness in the grain-boundary bonding results in the movement of adjace nt grains by a sliding mechanism which dominated the indentation aniso tropy effect. The presence of microcracking in the grain and at the gr ain boundary was found to affect the hardness anisotropy.