Yann Lorris Müller^1*, Anirudh Raju Natarajan^1,2*

1 Laboratory of Materials Design and Simulation (MADES), Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Vaud, Switzerland

2 National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne (EPFL), Switzerland

* Corresponding authors emails: yann.muller@epfl.ch, anirudh.natarajan@epfl.ch

DOI10.24435/materialscloud:th-d5 [version v1]

Publication date: May 14, 2024

How to cite this record

Yann Lorris Müller, Anirudh Raju Natarajan, First-principles thermodynamics of precipitation in aluminum-containing refractory alloys, Materials Cloud Archive 2024.72 (2024), https://doi.org/10.24435/materialscloud:th-d5

Description

Materials for high-temperature environments are actively being investigated for deployment in aerospace and nuclear applications. This study uses computational approaches to unravel the crystallography, and thermodynamics of a promising class of refractory alloys containing aluminum. Accurate first-principles calculations, cluster expansion models, and statistical mechanics techniques are employed to rigorously analyze precipitation in a prototypical senary Al-Nb-Ta-Ti-V-Zr alloy. Finite-temperature calculations reveal a strong tendency for aluminum to segregate to a single sublattice at elevated temperatures. Precipitate and matrix compositions computed with our ab-initio model are in excellent agreement with previous experimental measurements (Soni et al., 2020). Surprisingly, conventional B2-like orderings are found to be both thermodynamically and mechanically unstable in this alloy system. Complex anti-site defects are essential to forming a stable ordered precipitate. Our calculations reveal that the instability of B2 compounds can be related to a simple electron counting rule across all binary alloys formed by elements in groups 4,5, and 6. The results of this study provide viable routes toward designing high-temperature materials for deployment in extreme environments.

Materials Cloud sections using this data

Files

File name	Size	Description
data.zip MD5md5:18a4ec013215c5bd9e95394ed8d0cfa6	246.2 MiB	DFT calculations of symmetrically unique orderings on bcc Al-Nb-Ta-Ti-V-Zr and transformation pathways

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External references

Keywords

cluster expansion ab initio alloy theory precipitation phase stability MARVEL