System Maintenance Notice

Please note that maintenance work is scheduled between 4 AM and 5 AM - CET. During this time, you may experience reduced performance. Thanks for your patience.

Publications

Journal Article Ppublish

PubMed: 42875486 DOI: 10.1038/s41586-026-11065-7

Competing mechanisms toughen bcc binary and medium-entropy alloys at 20 K.

Nature 658(8137):923-929

Authors: David H Cook, Xiaoyu Chen, Michael O'Leary, Satish Rao, Wenqing Wang, Calvin H Belcher, Madelyn Payne, Pedro Borges, Tung Lik Lee, Arun Devaraj, Mark Asta, Enrique J Lavernia, Diran Apelian, Andrew M Minor, Dong Liu, Punit Kumar, Robert O Ritchie

Affiliations

  • Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA.
  • Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
  • Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
  • Department of Physics, University of Bristol, Bristol, UK.
  • Department of Materials Science and Engineering, University of California, Irvine, Irvine, CA, USA.
  • ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot, UK.
  • Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA.
  • Department of Materials Science and Engineering, Texas A&M University, College Station, TX, USA.
  • National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
  • Department of Engineering Science, University of Oxford, Oxford, UK.
  • Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA. School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, Singapore.
  • Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA.
  • Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.

Abstract

Plastic deformation in body-centred cubic (bcc) metals and alloys is conventionally mediated by screw dislocations. Their temperature-sensitive motion is attributed to a steep rise in strength with decreasing temperature that constricts plastic zones at crack tips, leading to a ductile-to-brittle transition 1. Here we evaluated the mechanical properties of group IV-V bcc refractory alloys with similar electronic structures at 20 K and found that these materials instead exhibit a plateau in tensile yield strength and fracture toughness as a function of temperature, with no apparent ductile-to-brittle transition. This behaviour arises from the global activation of twinning and an ω-phase transformation, which nucleate dislocations at interfaces before global dislocation motion. The initial mechanism is temperature insensitive and controls yielding, thereby preventing a crack-tip plastic zone from constricting with decreasing temperature.

MeSH

Alloys, Joint Dislocations, Plastics, Temperature