Understanding the Formation of Complex Phases: The Case of FeSi2
[4];
[1]
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- NAS of Ukraine, Kyiv (Ukraine). Inst. of Problems for Material Sciences
- Jackson State Univ., Jackson, MS (United States); Badger Technical Services LLC, Vicksburg, MS (United States)
- Jackson State Univ., Jackson, MS (United States)
One of the fundamental goals of materials science is to understand and predict the formation of complex phases. In this study, FeSi2 is considered as an illustration of complex phase formation. Although Fe and Si both crystallize with a simple structure, namely, body-centered cubic (bcc A2) and diamond (A4) structures, respectively, it is rather intriguing to note the existence of two complex structures in the Si-rich part of the phase diagram around FeSi2: α-FeSi2 at high temperatures (HT) with a slight iron-deficient structure and β-FeSi2 (also referred to as Fe3Si7) at low temperatures (LT). We re-analyze the geometry of these two phases and rely on approximant phases that make the relationship between these two phases simple. To complete the analysis, we also introduce a surrogate of the C16 phase that is observed in FeGe2. We clearly identify the relationship that exists between these three approximant phases, corroborated by a ground-state analysis of the Ising model for describing ordering that takes place between the transition metal element and the “vacancies”. This work is further supported by ab initio electronic structure calculations based on density functional theory in order to investigate properties and transformation paths. Finally, extension to other alloys, including an entire class of alloys, is discussed.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program
- Grant/Contract Number:
- AC52-07NA27344; 22-SI-007
- OSTI ID:
- 2305597
- Report Number(s):
- LLNL-JRNL-843253; 1065888
- Journal Information:
- Applied Sciences, Vol. 13, Issue 23; ISSN 2076-3417
- Publisher:
- MDPICopyright Statement
- Country of Publication:
- United States
- Language:
- English
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