Slip in directionally solidified Mo-alloy micropillars - Part I: Nominally dislocation-free pillars

In situ Laue analysis during microcompression reveals plasticity in [0 0 1]-oriented, directionally solidified Mo alloy pillars to start with slip on the {1 1 2} system having the highest Schmid factor followed by slip on the (1 1 0) plane containing the same Burgers vector. The results are interpreted in terms of the microstructure analyzed by scanning transmission electron microscopy and 3-D atom probe. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

[1]  F. Nabarro,et al.  Dislocations in solids , 1979 .

[2]  H. V. Swygenhoven,et al.  Smaller is stronger: The effect of strain hardening , 2009 .

[3]  G. Pharr,et al.  Scanning transmission electron microscope observations of defects in as-grown and pre-strained Mo alloy fibers , 2011 .

[4]  R. Smith,et al.  A computational search for ductilizing additives to Mo , 2005 .

[5]  G. Pharr,et al.  Compressive strengths of molybdenum alloy micro-pillars prepared using a new technique , 2007 .

[6]  G. Pharr,et al.  Effects of focused ion beam milling on the compressive behavior of directionally solidified micropillars and the nanoindentation response of an electropolished surface , 2009 .

[7]  V. Vítek,et al.  Atomistic study of non-Schmid effects in the plastic yielding of bcc metals , 2001 .

[8]  H. Van Swygenhoven,et al.  Time-resolved Laue diffraction of deforming micropillars. , 2007, Physical review letters.

[9]  Easo P George,et al.  Microstructures and mechanical properties of a directionally solidified NiAl–Mo eutectic alloy , 2005 .

[10]  O. Kraft,et al.  Size dependent mechanical behaviour of tantalum , 2011 .

[11]  C. P. Frick,et al.  Strain bursts in plastically deforming molybdenum micro- and nanopillars , 2008, 0802.1843.

[12]  H. V. Swygenhoven,et al.  Effects of focused ion beam milling and pre-straining on the microstructure of directionally solidified molybdenum pillars: A Laue diffraction analysis , 2010 .

[13]  E. Arzt,et al.  Correlation between critical temperature and strength of small-scale bcc pillars. , 2009, Physical review letters.

[14]  D. Dimiduk,et al.  Sample Dimensions Influence Strength and Crystal Plasticity , 2004, Science.

[15]  C. Woodward,et al.  Flexible Ab initio boundary conditions: simulating isolated dislocations in bcc Mo and Ta. , 2002, Physical review letters.

[16]  M. Tang,et al.  Dislocation mobility and the mechanical response of b.c.c. single crystals: A mesoscopic approach , 1998 .

[17]  D. Rodney,et al.  Chapter 88 Dislocation–Obstacle Interactions at the Atomic Level , 2009 .

[18]  H. Bei,et al.  Spatially resolved strain measurements in Mo-alloy micropillars by differential aperture x-ray microscopy , 2008 .

[19]  S. Tewari,et al.  Deformation and fracture behavior of Ni-Mo-Al (γ/γ′-α)in situ composite , 1984 .

[20]  H. V. Swygenhoven,et al.  Slip in directionally solidified Mo-alloy micropillars-Part II: Pillars containing defects , 2012 .

[21]  K. Jacobsen,et al.  Density functional theory studies of screw dislocation core structures in bcc metals , 2003 .

[22]  D. Caillard An in situ study of hardening and softening of iron by carbon interstitials , 2011 .

[23]  Marc Fivel,et al.  The glide of screw dislocations in bcc Fe: Atomistic static and dynamic simulations ☆ , 2006 .

[24]  Christopher R. Weinberger,et al.  Surface-controlled dislocation multiplication in metal micropillars , 2008, Proceedings of the National Academy of Sciences.

[25]  Julia R. Greer,et al.  Comparing the strength of f.c.c. and b.c.c. sub-micrometer pillars: Compression experiments and dislocation dynamics simulations , 2008 .

[26]  G. Taylor Thermally-activated deformation of BCC metals and alloys , 1992 .

[27]  V. Vitek,et al.  Multiscale modeling of plastic deformation of molybdenum and tungsten: I. Atomistic studies of the core structure and glide of 1/2〈1 1 1〉 screw dislocations at 0 K , 2008 .

[28]  G. Pharr,et al.  Effects of pre-strain on the compressive stress-strain response of Mo-alloy single-crystal micropillars , 2008 .

[29]  Julia R. Greer,et al.  Insight into the deformation behavior of niobium single crystals under uniaxial compression and tension at the nanoscale , 2009 .

[30]  A. Minor,et al.  Achieving the ideal strength in annealed molybdenum nanopillars , 2010 .