Anisotropic plastic and elastic deformation in highly textured superconducting (Bi, Pb)₂ Sr₂ Ca₂ Cu₃O_x ceramics

Abstract

A highly textured (Bi, Pb)₂Sr₂Ca₂Cu₃O_x superconductor has been prepared and the hardness, deformation and microcracking of the material explored using Vickers indentation. The present study has investigated the hardness anisotropy of the highly textured material on cross-sections of the specimen which have been chosen to give specific low-index orientations. The hardness was found to decrease as the indentation rotated from 0 ° (a diagonal of the indent parallel to the direction of the texturing) to 45 ° (the angle between a diagonal of the indent and the direction of the texturing). The square shape of the indent also changed with rotation from 0 ° to 45 °. The hardness anisotropy has been attributed to the influence of elastic and plastic anisotropy in the polycrystalline materials. In addition, a weakness in the grain-boundary bonding results in the movement of adjacent grains by a sliding mechanism which dominated the indentation anisotropy effect. The presence of microcracking in the grain and at the grain boundary was found to affect the hardness anisotropy.