POLARIZED-LIGHT MICROSTRUCTURE ANALYSIS OF MELT-TEXTURED DYBA2CU3O7-XCERAMICS

We report the microstructure of magnetically melt-textured Dy-123 samp les, as observed by polarized light metallography. The phase dimension s, morphology, orientation, nature, and distribution are outlined. Gra in, twin structure pattern, and grain boundary are characterized. The relationship among cracking, secondary phases, and tetragonal-orthorho mbic phase transformation is discussed, The results are obtained by ob serving a ''not-too-well-ordered'' region. This leads to definite conc lusions on the relationship between crack spacing and 211 distribution , and to some confirmation of the growth mechanism and on macro- and m icrocrack origins. From the present observations, the effect of the ox ygenation process and the quantification of the tensile stress in the materials can also be obtained.