QUANTITATIVE MEASUREMENTS OF SEGREGATION IN Co-Cr-X MAGNETIC RECORDING MEDIA BY EN ERGY-FILTERED TRANSMISSION ELECTRON MICROS COPY

摘要

Reliable core-loss spectroscopic methods have been developed for mapping elemental segregation in Co-Cr-X magnetic recording media by energy-filtered transmission electron microscopy. Extraction of quantitative compositions at a spatial resolution approaching 1 nm involves sophisticated treatments for diffraction contrast, variations in specimen thickness, and closely-spaced oxygen K and chromium L_(23) ionization edges. These methods reveal that intergranular chromium levels are ～25 at.% for random-angle boundaries and ～15 at.% for 90° boundaries in films of Co_(84)Cr_(12)Ta_4 d.c. magnetron sputtered at 250℃.