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Published January 2012 | public
Journal Article

Crystallographic orientation and size dependence of tension–compression asymmetry in molybdenum nano-pillars

Abstract

Uniaxial tension and compression experiments on [0 0 1] and [0 1 1] oriented molybdenum nano-pillars exhibit tension–compression asymmetry, a difference in attained stresses in compression vs. tension, which is found to depend on crystallographic orientation and sample size. We find that (1) flow stresses become higher at smaller diameters in both orientations and both loading directions, (2) compressive flow stresses are higher than tensile ones in [0 0 1] orientation, and visa versa in [0 1 1] orientation, and (3) this tension–compression asymmetry is in itself size dependent. We attribute these phenomena to the dependence of twinning vs. antitwinning deformation on loading direction, to the non-planarity of screw dislocation cores in Mo crystals, and to the possibly lesser role of screw dislocations in governing nano-scale plasticity compared with bulk Mo.

Additional Information

© 2011 Elsevier Ltd. Received 15 December 2010; revised 21 April 2011; Available online 12 June 2011. This work was supported by Office of Naval Research under Grant No. N00014-09-1-0883. The authors gratefully acknowledge A. Buxbaum from FEI Company for TEM sample preparation, and critical support and infrastructure for this work provided by the Kavli Nanoscience Institute (KNI) at Caltech.

Additional details

Created:
September 14, 2023
Modified:
October 23, 2023