Abstract
The phase equilibria of an Al0.5CrFeCoNiCu High Entropy Alloy has been studied following 1000h exposures at 700, 850 and 1000°C. Above 1000°C, the material comprised of two fcc solid solutions, one a multi-element phase and the other a Cu rich phase. Below 1000°C, the fcc phases persisted, but were accompanied by the formation of two intermetallic compounds. In contrast to previous reports, the L12 phase was also found to precipitate through a solvus at~850°C. The results indicated that a solid state single phase field does not exist in this material at any temperature and all of the observed phases could be rationalised with reference to existing phase diagrams. This suggests that configurational entropy does not overcome the enthalpic contribution to the Gibbs energy, which governs phase equilibria of this alloy.
Highlights
High Entropy Alloys (HEAs) are an intriguing new class of metallic materials, based on a novel approach to materials design
The basis for this hypothesis lies in classical thermodynamics, where the entropy of mixing between two soluble components is at its maximum when the constituent elements are in equiatomic concentrations
In order to resolve these inconsistencies, we report on the elemental partitioning and phase equilibria of Al0.5CrFeCoNiCu following 1000 h exposures at 700, 850 and 1000 1C from the ascast state
Summary
High Entropy Alloys (HEAs) are an intriguing new class of metallic materials, based on a novel approach to materials design. Experimental studies have reported single or dual phase as-cast microstructures [2,3,4,5], and corresponding diffraction data have indicated that these phases have simple crystal structures, such as fcc or bcc To rationalise these observations, it has been postulated that the entropy of mixing in these multi-component systems must be very high, resulting in entropically stabilised solid solution phases [1,2]. It has been postulated that the entropy of mixing in these multi-component systems must be very high, resulting in entropically stabilised solid solution phases [1,2] The basis for this hypothesis lies in classical thermodynamics, where the entropy of mixing between two soluble components is at its maximum when the constituent elements are in equiatomic concentrations. It can be seen that the entropy of an equiatomic multi-component system would be expected to increase with the number of constituent elements
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
