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Chromium Distribution in CoCrTa/Cr Longitudinal Recording Media

Published online by Cambridge University Press:  10 February 2011

J.E. Wittig
Affiliation:
Vanderbilt University, Nashville TN 37235
T.P. Nolan
Affiliation:
Komag Inc., 1704 Automation Parkway, San Jose CA 95131
R. Sinclair
Affiliation:
Stanford University, Palo Alto CA 94305
J. Bentley
Affiliation:
ORNL, Oak Ridge TN 37831
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Abstract

The current study of CoCr12Ta4/Cr longitudinal recording media combines high resolution electron microscopy (HRTEM) with nanoprobe energy dispersive spectroscopy (EDS) and energy-filtered imaging (EFTEM) to correlate the Cr distribution with specific microstructural features. EFTEM images show Cr enrichment at grain boundaries, both random angle boundaries and 90° bicrystal boundaries. Cr segregation within grains is also observed in the elemental maps. This intragrain segregation often occurs at a series of defects that may define separately nucleated grains having 00 misorientation. Nanoprobe EDS measurements indicate that these defects contain localized concentrations of 25 to 30 % Cr. The random angle grain boundary Cr concentration occurs with a wide range, 19 to 36 at% (mean 22%) whereas the more crystallographically related 900 boundaries contain less Cr with less variation, 15 to 21 at% (mean 17% Cr). Composition profiles across grain boundaries using both nanoprobe EDS and EFTEM images show the full-width-half-maximum of the segregation to be approximately 4 nm, with Cr depleted regions next to the grain boundary having less than 7 at% Cr. The Ta concentration revealed no statistical evidence of segregation.

Type
Research Article
Copyright
Copyright © Materials Research Society 1998

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