Amorphous metallic alloys, or metallic glasses, are lucrative engineering materials owing to their superior mechanical properties such as high strength and large elastic strain. However, their main drawback is their propensity for highly catastrophic failure through rapid shear banding, significantly undercutting their structural applications. Here, we show that when reduced to 100 nm, Zr-based metallic glass nanopillars attain ceramic-like strengths (2.25 GPa) and metal-like ductility (25%) simultaneously. We report separate and distinct critical sizes for maximum strength and for the brittle-to-ductile transition, thereby demonstrating that strength and ability to carry plasticity are decoupled at the nanoscale. A phenomenological model for size dependence and brittle-to-homogeneous deformation is provided.
At a glance
- Size dependence of mechanical properties of gold at the micron scale in the absence of strain gradients. Acta Mater. 53, 1821–1830 (2005). , &
- Sample dimensions influence strength and crystal plasticity. Science 305, 986–989 (2004). , , &
- Non-crystalline structure in solidified gold–silicon alloys. Nature 187, 869–870 (1960). , &
- Metallic glasses as structural materials. Scr. Mater. 54, 321–326 (2006). &
- Overview no. 144—mechanical behavior of amorphous alloys. Acta Mater. 55, 4067–4109 (2007). , &
- Formation of bulk metallic glasses and their composites. MRS Bull. 32, 624–628 (2007). et al.
- Ductile crystalline-amorphous nanolaminates. Proc. Natl Acad. Sci. USA 104, 11155–11160 (2007). , , &
- Designing metallic glass matrix composites with high toughness and tensile ductility. Nature 451, 1085–1089 (2008). et al.
- Plastic flow and failure resistance of metallic glass: Insight from in situ compression of nanopillars. Phys. Rev. B 77, 155419 (2008). et al.
- Effect of sample size on deformation in amorphous metals. J. Appl. Phys. 103, 083539 (2008). , &
- Bulk and microscale compressive properties of a Pd-based metallic glass. Scr. Mater. 57, 517–520 (2007). et al.
- Size-independent strength and deformation mode in compression of a Pd-based metallic glass. Acta Mater. 56, 5091–5100 (2008). , , &
- Bulk and microscale compressive behavior of a Zr-based metallic glass. Scr. Mater. 58, 890–893 (2008). et al.
- Sample size effect and microcompression of Mg65Cu25Gd10 metallic glass. Appl. Phys. Lett. 91, 161913 (2007). , &
- Prevalence of shear banding in compression of Zr41Ti14Cu12.5Ni10Be22.5 pillars as small as 150 nm in diameter. Acta Mater. 57, 3562–3571 (2009). , , &
- Micropillar compression studies on a bulk metallic glass in different structural states. Scr. Mater. 60, 567–570 (2009). , , , &
- Strength of submicrometer diameter pillars of metallic glasses investigated with in situ transmission electron microscopy. Phil. Mag. Lett. 89, 633–640 (2009). , &
- Micro-compression testing: A critical discussion of experimental constraints. Mater. Sci. Eng. A 505, 79–87 (2009). , &
- 3rd edn (Elsevier Butterworth-Heinemann, 2005). Materials Selection in Mechanical Design
- Revealing the maximum strength in nanotwinned copper. Science 323, 607–610 (2009). , , &
- Molecular dynamics simulation of intrinsic and extrinsic mechanical properties of amorphous metals. Intermetallics 14, 1005–1010 (2006). &
- Tensile ductility and necking of metallic glass. Nature Mater. 6, 735–739 (2007). et al.
- Malleable hypoeutectic Zr–Ni–Cu–Al bulk glassy alloys with tensile plastic elongation at room temperature. Phil. Mag. Lett. 89, 322–334 (2009). , , &
- 2nd edn (McGraw-Hill, 2000). Mechanical Behavior of Materials
- Fracture toughness study of new Zr-based Be-bearing bulk metallic glasses. Scr. Mater. 60, 80–83 (2009). et al.
- Plastic deformation in metallic glasses. Acta Metall. 27, 47–58 (1979).
- An elastic to plastic transition in metallic glass-forming liquids. Phys. Rev. Lett. 99, 135502 (2007). , , &
- A microscopic mechanism for steady state inhomogeneous flow in metallic glasses. Acta Metall. 25, 407–415 (1977).
- Materials become insensitive to flaws at nanoscale: Lessons from nature. Proc. Natl Acad. Sci. USA 100, 5597–5600 (2003). , , , &
- A universal criterion for plastic yielding of metallic glasses with a (T/T-g)(2/3) temperature dependence. Phys. Rev. Lett. 95, 195501 (2005). &