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Citation: P. Wang, Y. Bu, J. Liu, Q. Li, H. Wang, and W. Yang (2020), "Atomic deformation mechanism and interface toughening in metastable high entropy alloy", Materials Today, 37, 64-73. DOI: 10.1016/j.mattod.2020.02.017.
Abstract: Metastable high entropy alloy (HEA) with excellent properties have attracted extensive attentions recently. However, as a consequence of limited experiments of high-resolution transmission electron microscopy (HRTEM) and the difficulties of molecular dynamic (MD) simulations for the phase transformation process, the detailed atomic deformation mechanisms in the HEA is not well understood. We carry out the in situ HRTEM observation of the martensitic transformation process and find surprisingly wide phase interface between the parent and the martensite in a typical high strength and high elongation metastable HEA. One specific interatomic potential is developed for the metastable HEA and large-scale MD simulation is carried out to investigate the martensitic transformation process from body-centered cubic to hexagonal close packed structures. The whole processes of the stress-induced martensitic transformation (nucleation, incubation, bursting and propagating of the new phase) are well reproduced in the MD simulations, suggesting its good agreements with the HRTEM observations. The width of the phase interface mainly depends on the competition between interfacial energy and lattice distortion energy during the martensitic transformation process. This wide phase interface acts as a buffer to coordinate the martensitic transformation induced strain and as a buffer storage for dislocation gliding and pile-up. As a result, the metastable HEA achieves a high strength combined with a large tensile elongation. The revealed atomic-scale deformation and corresponding interatomic potential should be useful to guide the design in the new series of high-performance metastable alloy.

Notes: Dr. Peng Wang notes that "This potential is developed base on the framework of meta-atom method which focuses on the direct relationship between material properties and their deformation mechanisms. In this method, a detailed distinction among various atomic species is discarded and an alloy system is represented by a set of meta-atom which is fitted to all related material properties. Once the completeness of material properties is established, two systems with the same properties are expected to deform identically. This method has been verified to be able to describe the mechanical behavior of binary alloys and multi-element alloys by different groups."

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Notes: This file was sent by P. Wang (Shanghai University) on 12 Oct. 2020 and posted with his permission.
Date Created: October 5, 2010 | Last updated: June 09, 2022