CHROMIUM SEGREGATION IN COCRTA CR AND COCRPT/CR THIN-FILMS FOR LONGITUDINAL RECORDING MEDIA/

Analytical electron microscopy is employed to correlate Cr segregation in Co84Cr12Ta4/CT and Co76Cr12Pt12/Cr films with specific microstruct ural features such as grain boundary mis-orientation. Energy-filtered (EFTEM) chemical maps show that Cr segregation occurs independently of the Cr underlayer, and is highly alloy dependent. The CoCrTa film con tained extensive grain boundary Cr enrichment whereas EFTEM images fro m the CoCrPt media show homogeneous Cr distribution. No statistically significant Ta or Pt segregation was observed. EFTEM elemental maps an d energy dipersive spectroscopy (EDS) indicate that grain boundary Cr segregation depends on the type of boundary. Quantitative analysis of the Cr levels using nanoprobe EDS shows that the random angle grain bo undaries contain more Cr (23 +/-4 at%) than 900 boundaries (17 +/-4 at %). EDS and EFTEM composition profiles show Cr enriched grain boundari es surrounded by regions of Cr depletion.