Polarized light microstructure analysis of melt-textured DyBa2Cu3O7-x ceramics

We report the microstructure of magnetically melt-textured Dy-123 samples, as observed by polarized light metallography. The phase dimensions, morphology, orientation, nature, and distribution are outlined. Grain, twin structure pattern, and grain boundary are characterized. The relationship among cracking, secondary phases, and tetragonal-orthorhombic phase transformation is discussed. The results are obtained by observing a "not-too-well-ordered" region. This leads to definite conclusions on the relationship between crack spacing and 211 distribution, and to some confirmation of the growth mechanism and on macro- and microcrack origins. From the present observations, the effect of the oxygenation process and the quantification of the tensile stress in the materials can also be obtained.