Scientists have discovered a way to make strong materials that are also ductile. One of life’s classic problems is that whenever a metal or alloy is altered to make it stronger, it loses its ability to deform – it becomes brittle, so its eventual failure is both unheralded and catastrophic. Nanostructured materials have shown great improvements in strength over their conventional counterparts, but until now, they have also typically been more brittle. Researchers have discovered that conventional levels of ductility can be achieved in high-strength nanostructured cobalt, when a planar-defect deformation mechanism called “twinning” is active. This was determined using real-time in-situ x-ray scattering during mechanical testing and post-deformation high-resolution electron microscopy. High-strength allows structures to be made with less material, and the consequent weight saving provides energy-efficiency improvements in transportation systems. This new discovery suggests a path forward to using high-strength materials in applications of this type, where brittleness is unacceptable.
- Y. M. Wang, R. T. Ott, A. V. Hamza, M. F. Besser, J. Almer, and M. J. Kramer. Achieving Large Uniform Tensile Ductility in Nanocrystalline Metals. Physical Review Letters 105, 215502, (2010). DOI: 10.1103/PhysRevLett.105.215502