Redefining plasticity in a cubic intermetallic: Dislocation dynamics in the CaAl2 Laves phase

Acta Materialia, vol. 303, pp. 121604

Abstract

In the realm of materials design, understanding and manipulating the behaviour of dislocations — key drivers of plastic deformation — is a cornerstone. However, while dislocations are well-explored in simple crystalline materials, their structure and mechanisms of motion remain largely enigmatic for complex crystals, such as topologically closed-packed phases. This vast class of materials contains many intermetallics ranging from high-temperature structural materials to functional crystals that can act as superconductors, magnets, magneto-caloric or hydrogen storage materials. In all of these applications, structural integrity and therefore controlled plasticity is essential. This study bridges our current knowledge gap in plasticity of complex crystals by delving into the most prevalent among them, the Laves phase. Utilizing transmission electron microscopy, we unveil previously unreported defect structures in the cubic CaAl 2 Laves phase. Complementing these observations, atomistic simulations elucidate the underpinning mechanisms, revealing novel deformation behaviours. We spotlight the role of full dislocations traversing multiple {1 1 n} slip planes, a departure from the conventional confinement to {1 1 1} planes. This multi-plane dislocation activity, including frequent cross-slipping, emerges as a pivotal factor in accommodating plastic deformation. Our findings not only challenge an existing paradigm in intermetallic plasticity but also propose a tangible pathway to understand the ductility of brittle complex alloys as a stride forward in phase selection and materials engineering.

Authors 7

1. Martina Freund corresponding Aachen Institut für Metallkunde und Materialphysik

   RWTH Aachen University

   Affiliation as printed

   Institut für Metallkunde und Materialphysik, RWTH Aachen University, 52056 Aachen, Germany

2. Joshua Spille Aachen Central Facility for Electron Microscopy

   RWTH Aachen University

   Affiliation as printed

   Central Facility for Electron Microscopy, RWTH Aachen University, 52056 Aachen, Germany

3. Pei‐Ling Sun Aachen Institut für Metallkunde und Materialphysik

   RWTH Aachen University

   Affiliation as printed

   Institut für Metallkunde und Materialphysik, RWTH Aachen University, 52056 Aachen, Germany

4. Marta Lipińska-Chwałek

   Forschungszentrum Jülich · Ernst Ruska Centre

   Affiliation as printed

   Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany

5. Joachim Mayer Aachen Central Facility for Electron Microscopy

   Forschungszentrum Jülich · Ernst Ruska Centre · RWTH Aachen University

   Affiliation as printed

   Central Facility for Electron Microscopy, RWTH Aachen University, 52056 Aachen, Germany

   Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany

6. Zhuocheng Xie corresponding Aachen Institut für Metallkunde und Materialphysik

   RWTH Aachen University

   Affiliation as printed

   Institut für Metallkunde und Materialphysik, RWTH Aachen University, 52056 Aachen, Germany

7. Sandra Korte‐Kerzel corresponding Aachen Institut für Metallkunde und Materialphysik

   RWTH Aachen University

   Affiliation as printed

   Institut für Metallkunde und Materialphysik, RWTH Aachen University, 52056 Aachen, Germany