Abstract
High-entropy alloys are random alloys with five or more components, often near equi-composition, that often exhibit excellent mechanical properties. Guiding the design of new materials across the wide composition space requires an ability to compute necessary underlying material parameters via ab initio methods. Here, density functional theory is used to compute the elemental misfit volumes, alloy lattice constant, elastic constants, and stable stacking fault energy in the fcc noble metal RhIrPdPtNiCu. These properties are then used in a recent theory for the temperature and strain-rate dependent yield strength. The parameter-free prediction of 583 MPa is in excellent agreement with the measured value of 527 MPa. This quantitative connection between alloy composition and yield strength, without any experimental input, motivates this general density functional theory-based methodological path for exploring new potential high-strength high-entropy alloys, in this and other alloy classes, with the chemical accuracy of first-principles methods.
Highlights
High-entropy alloys (HEAs), called multiple principal element alloys, nominally consist of five or more elements at near-equal compositions in a single crystalline phase.[1]
Since there is no physical restriction to near-equi-composition random alloys, the available composition space for multi-property optimization is vast
We present a new and general method to compute the required solute misfit volumes in the multicomponent random alloys, which enables parameter-free and experiment-free prediction of the yield strength
Summary
High-entropy alloys (HEAs), called multiple principal element alloys, nominally consist of five or more elements at near-equal compositions in a single crystalline phase.[1]. Searching through that space can be greatly facilitated by theory and modeling for both property prediction and phase stability. Accurate predictions require both accurate theories and the chemically accurate inputs to those models, and the latter leads to the application of first-principles methods. A general theory has been developed to predict the temperature and strain-rate dependent yield strength in random fcc alloys.[7,8] The theory envisions the HEA as an “effective-medium matrix”, and each elemental atom in the alloy acts as a solute in the effective matrix. We present a new and general method to compute the required solute misfit volumes in the multicomponent random alloys, which enables parameter-free and experiment-free prediction of the yield strength. Good agreement with experiment is achieved, establishing the overall methodology as a framework for computationally guided design of new fcc HEAs
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