Chemically tailored planar defect phases in the Ta-Fe μ-phase

Acta Materialia, vol. 314, pp. 122248

Abstract

Intermetallics often exhibit complex crystal structures, which give rise to intricate defect structures that critically influence their mechanical and functional properties. Despite studies on individual defect types, a comprehensive understanding of the defect landscape in μ -phases, a class of topologically close-packed phases, remains elusive. In this study, we investigated the planar defect structures in the Ta-Fe μ -phase across a compositional range of 46 to 58 at.% Ta using electron microscopy and density functional theory calculations. Electron backscatter diffraction and high-resolution scanning transmission electron microscopy reveal a transition from basal twin boundaries and planar faults containing C14 TaFe 2 Laves phase layers at a low Ta content to pyramidal { 1 1 ̄ 02 } twins at a higher Ta content. Density functional theory calculations of defect formation energies confirm a chemical potential-driven stabilisation of Laves phase lamellae. The prevalence of pyramidal twins in Ta-rich μ -phase samples is attributed to the competitive nature of different planar defects during solidification. A defect landscape for μ -phases is proposed, illustrating the interplay between site occupancy, dislocation types and planar faults across the chemical potential space. These findings provide fundamental insights into defect engineering in structurally complex intermetallics and open pathways for optimising material properties through chemical tuning.

Authors 8

1. Christina Gasper corresponding Aachen Institute for Physical Metallurgy and Materials Physics

   RWTH Aachen University

   Affiliation as printed

   Institute for Physical Metallurgy and Materials Physics, RWTH Aachen University, 52074 Aachen, Germany

2. Nisa Ulumuddin Aachen Institute for Physical Metallurgy and Materials Physics

   RWTH Aachen University

   Affiliation as printed

   Institute for Physical Metallurgy and Materials Physics, RWTH Aachen University, 52074 Aachen, Germany

3. Siyuan Zhang corresponding

   Max-Planck-Institut für Nachhaltige Materialien

   Affiliation as printed

   Max Planck Institute for Sustainable Materials, 40237 Düsseldorf, Germany

4. Sang-Hyeok Lee Aachen Institute for Physical Metallurgy and Materials Physics

   RWTH Aachen University

   Affiliation as printed

   Institute for Physical Metallurgy and Materials Physics, RWTH Aachen University, 52074 Aachen, Germany

5. Christina Scheu

   Max-Planck-Institut für Nachhaltige Materialien

   Affiliation as printed

   Max Planck Institute for Sustainable Materials, 40237 Düsseldorf, Germany

6. Benjamin Berkels Aachen Aachen Institute for Advanced Study in Computational Engineering Science (AICES)

   Aachen Institute for Advanced Study in Computational Engineering Science · RWTH Aachen University

   Affiliation as printed

   Aachen Institute for Advanced Study in Computational Engineering Science, RWTH Aachen University, 52062 Aachen, Germany

7. Zhuocheng Xie corresponding Aachen Institute for Physical Metallurgy and Materials Physics

   RWTH Aachen University

   Affiliation as printed

   Institute for Physical Metallurgy and Materials Physics, RWTH Aachen University, 52074 Aachen, Germany

8. Sandra Korte‐Kerzel corresponding Aachen Institute for Physical Metallurgy and Materials Physics

   RWTH Aachen University

   Affiliation as printed

   Institute for Physical Metallurgy and Materials Physics, RWTH Aachen University, 52074 Aachen, Germany