Residual strain and texture in free-standing nanoscale Cu-Nb multilayers

C. C. Aydiner, D. W. Brown, A. Misra, N. A. Mara, Y. C. Wang, J. J. Wall, J. Almer

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Abstract

We investigate the residual strains in a free-standing Cu/Nb multilayer of 30 nm nominal layer thickness with synchrotron x-rays. This material system is characterized by columnar grains of Cu and Nb with incoherent interfaces and a sharp physical-vapor-deposition texture. High energy x-rays were used with an area detector along with multiple sample rotations to yield diffraction strain components in a very large number of directions. Due to the texture and the elastic anisotropy of constituents, observed diffraction strains cannot be derived from a single strain tensor (also known as linear sin2 ψ). Orientation-dependent diffraction strain modeling is utilized with a Vook-Witt micromechanical model. Obtained phase-resolved in-plane stress magnitudes are -515 MPa in Nb and +513 MPa in Cu, satisfying force equilibrium within experimental errors. The stresses of this magnitude will certainly influence the mechanical behavior of the multilayer upon further loading. The Vook-Witt model describes the Nb diffraction strains very well, and thereby provides information on the stress distribution in crystallites as a function of their orientation. On the other hand, the same level of agreement with the Vook-Witt model has not been achieved for Cu diffraction strains.

Original languageEnglish (US)
Article number083514
JournalJournal of Applied Physics
Volume102
Issue number8
DOIs
StatePublished - 2007

Bibliographical note

Funding Information:
C.C.A. acknowledges the support of NNSA’s Laboratory Directed Research and Development Program. A.M. and his LANL collaborators acknowledge support from DOE, Office of Science, Office of Basic Energy Sciences.

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