Theory of strengthening in fcc high entropy alloys
Abstract
High Entropy Alloys (HEAs) are a new class of random alloys having impressive strength and toughness. Here, a mechanistic, parameter-free, and predictive theory for the temperature-, composition-, and strain-rate-dependence of the plastic yield strength of fcc HEAs is presented, validated, and applied to understand recent experiments. To first order, each elemental component in the HEA is considered as a solute embedded in the effective matrix of the surrounding alloy. Strengthening is then mainly achieved due to dislocation interactions with the random local concentration fluctuations around the average composition. The theory is validated against molecular simulations on model Fe-Ni-Cr alloys. Hall-Petch-corrected yield strengths in Ni-Co-Fe-Cr-Mn fcc HEAs are then predicted using only available experimental information, and good quantitative agreement is achieved. The theory demonstrates the origins of the high strength and detailed trends with composition, materials parameters, temperature, thus identifying the key measurable/calculable material properties needed for design and optimization of fcc HEAs, and is a general model for fcc random alloys.
- Publication:
-
Acta Materialia
- Pub Date:
- October 2016
- DOI:
- 10.1016/j.actamat.2016.07.040
- Bibcode:
- 2016AcMat.118..164V
- Keywords:
-
- High entropy alloys;
- Mechanical properties;
- Solution strengthening theory;
- Yield stress;
- Molecular simulations