Competing mechanisms toughen bcc binary and medium-entropy alloys at 20 K
Year: 2026
Type: article
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.
Source: Nature
Institutions: Lawrence Berkeley National Laboratory, University of California, Berkeley, University of Bristol, University of California, Irvine, Rutherford Appleton Laboratory, ISIS Neutron and Muon Source, Pacific Northwest National Laboratory, Texas A&M University, Molecular Foundry, University of Oxford, Science Oxford, Nanyang Technological University
Language: English
Topic: High Entropy Alloys Studies
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $12,690
OpenAlex ID: W7222006751