Abstract
High-entropy alloys constitute a new class of materials whose very existence poses fundamental questions regarding the physical principles underlying their unusual phase stability. Originally thought to be stabilized by the large entropy of mixing associated with their large number of components (five or more), these alloys have attracted attention for their potential applications. Yet, no model capable of robustly predicting which combinations of elements will form a single phase currently exists. Here, we propose a model that, through the use of high-throughput computation of the enthalpies of formation of binary compounds, predicts specific combinations of elements most likely to form single-phase, high-entropy alloys. The model correctly identifies all known single-phase alloys while rejecting similar elemental combinations that are known to form an alloy comprising multiple phases. In addition, we predict numerous potential single-phase alloy compositions and provide three tables with the ten most likely five-, six-, and seven-component single-phase alloys to guide experimental searches.
- Received 5 November 2014
DOI:https://doi.org/10.1103/PhysRevX.5.011041
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Published by the American Physical Society
Popular Summary
High-entropy alloys (HEAs) are a new class of materials with five or more elements. These alloys have significant potential as structural materials because of their strength, ductility, and ability to resist corrosion. HEAs differ from most other alloys in which adding more elements results in phase transitions. Theoretically identifying new HEA compositions by calculating properties of randomly assembled alloys from different elements is computationally infeasible; the set of alloys containing seven elements numbers in the millions.
We instead examine the properties of competing binary compounds for every pair of elements within a given multi-element HEA to predict which ensembles of elements will form HEAs. We devise a model that accounts for all known elemental combinations known to form HEAs while rejecting those combinations that form multiple phases. The model relies on a matrix of enthalpies derived from high-throughput calculations. We present a set of five-, six-, and seven-component alloys to guide experimental studies. Our model can be customized with different criteria (such as the annealing temperature) and can also be programmed to take into account real-world considerations such as the relative prices of the alloys. Our findings are also in good agreement with experiments conducted thus far, including the identification of materials that violate well-known Hume-Rothery rules.
We expect that our results will motivate experimental verification of these HEAs, which have promising industrial applications. This work is an important step toward discovering complex alloys with novel and desirable properties.
