Summary: Estimates of interfacial properties in Cu/Ni multilayer thin films
using hardness data
P.M. Anderson* and J.S. Carpenter
Department of Materials Science and Engineering, The Ohio State University, 2041 College Rd., Columbus, OH 43210, USA
Received 5 August 2009; revised 9 October 2009; accepted 10 October 2009
Available online 22 October 2009
Modeling the defect structure and mechanical properties of metallic multilayer thin films requires estimates of dislocation param-
eters such as interfacial line energy and barrier strength, as well as resistance to confined layer slip. A method is presented to estimate
these parameters using experimental measurements of hardness vs. individual layer thickness h. Application to Cu/Ni multilayers
suggests that the interfacial line energy increases dramatically with h (5 6 h 6 50 nm), far in excess of values assumed in analytic
and dislocation dynamics models.
” 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Keywords: Multilayer thin films; Interfaces; Modeling; Dislocations; Internal stresses
Hardness values for metallic multilayer thin
films frequently depart from the classic Hall≠Petch rela-
tion when the individual layer thickness h < 50 nm [1≠4].
In this regime, confined layer slip (CLS) within individ-
ual layers is viewed as an important deformation mech-
anism [2,5,6]. However, predictions of hardness vs.
bilayer period based on this mechanism do not agree