English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

Refractory multi-element alloys (RMEA) with body-centered cubic (bcc)structure have been the object of much research over the last decade due totheir high potential as candidate materials for high-temperature applications.Most of these alloys display a remarkable strength at high temperatures, whichcannot be explained by the standard model of bcc plasticity dominated bythermally-activated screw dislocation motion. Recent research on Nb-Mo-Ta-Walloys points to a heightened role of edge dislocations on deformation, whichis generally attributed to atomic-level chemical fluctuations in the materialand their interactions with dislocation cores during slip. However, while thismodel accounts for a strengthening effect due to the chemical complexity of thealloy, it is not sufficient to explain its strength across the entire thermalrange. Here we propose a new mechanism that captures the existing theoriesabout enhanced lattice strengthening and a thermally-activated component thatemanates directly from the chemical complexity of the RMEA. This compositionalcomplexity results in unique vacancy formation energy distributions with tailsthat extend into negative energies, leading to spontaneous, i.e., athermal,vacancy formation at edge dislocation cores. These vacancies relax intoatomic-sized super-jogs on the dislocation line, acting as extra pinning pointsthat increase the activation stress of the dislocation. At the same time, thesesuper-jogs can displace diffusively along the glide direction, relieving withtheir motion some of the extra stress, thus countering the hardening effect dueto jog-pinning. The interplay between these two processes as a function oftemperature confers an extra strength to edge dislocation atintermediate-to-high temperatures, in remarkable agreement with experimentalmeasurements in Nb-Mo-Ta-W and across a number of different RMEA.

Thermal super-jogs control high-temperature strength in Nb-Mo-Ta-W alloys