A quantitative evaluation method for particle orientation structure in alumina powder compacts

A quantitative evaluation method was developed to analyze weak-moderate particle orientation in alumina green compacts based on the optical anisotropy measured with a polarized light microscope. Alumina compacts of various structures were prepared in high magnetic fields 0–10 T by a casting method. The compact was made transparent with an immersion liquid, and the retardation of polarized light through it was measured quantitatively using a polarized light microscope with a Berek compensator. The degree of particle orientation was defined as the ratio of birefringence of the compact to that of alumina single crystal perpendicular to the c-axis. The degrees of orientation thus evaluated were compared to those calculated from X-ray diffraction analysis for samples with high orientation, and were found to agree very well.