Deformation twins as a probe for tribologically induced stress states

• Published in: Communications materials Vol. 5; no. 1; pp. 4 - 10
• Main Authors: Dollmann, Antje, Kübel, Christian, Tavakkoli, Vahid, Eder, Stefan J., Feuerbacher, Michael, Liening, Tim, Kauffmann, Alexander, Rau, Julia, Greiner, Christian
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 05.01.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 639/166/988; 639/301; Anisotropy; Chemistry and Materials Science; Contact stresses; Deformation; Grain orientation; High entropy alloys; Materials Science; Microstructure; Molecular dynamics; Room temperature; Single crystals; Stress distribution; Tribology; Twinning; Wear
• ISSN: 2662-4443; 2662-4443
• DOI: 10.1038/s43246-023-00442-8

Friction and wear of metals are critically influenced by the microstructures of the bodies constituting the tribological contact. Understanding the microstructural evolution taking place over the lifetime of a tribological system therefore is crucial for strategically designing tribological systems with tailored friction and wear properties. Here, we focus on the single-crystalline High-Entropy Alloy CoCrFeMnNi that is prone to form twins at room temperature. Deformation twins feature a pronounced orientation dependence with a tension-compression anisotropy, a distinct strain release in an extended volume and robust onset stresses. This makes deformation twinning an ideal probe to experimentally investigate the complex stress fields occurring in a tribological contact. Our results unambiguously show a grain orientation dependence of twinning under tribological load. It is clearly shown, that twinning cannot be attributed to a single crystal direction parallel to a sample coordinate axes. With deformation twins in the microstructure, stress field models can be validated to make them useable for all different tribological systems. A complex relationship exists between microstructure development and stress field during tribological loading of a metal. Here, twinning in a high-entropy alloy is used as a model system to understand stress fields during tribological experiments, supported by molecular dynamics simulations.