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Depth-Dependent Hardness Improvements in Ion Irradiated Polystyrene

Published online by Cambridge University Press:  21 February 2011

Gopal R. Rao
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6376, U.S.A.
Laura Riester
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6376, U.S.A.
Eal H. Lee
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6376, U.S.A.
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Abstract

Polystyrene (PS) was irradiated with 2 MeV He+ ions to a fluence of 3.3×1019 ions/m2. A cross-section of the irradiated layer was subjected to hardness measurements across the section using a nanoindentation technique. Results showed that hardness increased as a function of irradiation depth and showed a maximum value of 12 GPa at a depth of approximately 6.5 μπι, for a total ion penetration range of 9 μιη, as compared to a hardness of 0.45 GPa for unirradiated PS. The hardness variation with depth followed the trend for Linear Energy Transfer (LET) for ionization from the energetic ions to substrate atoms. This investigation showed for the first time how hardness varies as a function of depth for ion-irradiated polymers; this variation approximately follows the ionization LET profile, suggesting that cross-linking in the polymers could be proportional to ionization.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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References

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