Deformation twins as a probe for tribologically induced stress states

TL;DR

This paper demonstrates that deformation twins in single-crystalline CoCrFeMnNi can serve as effective probes for complex stress fields in tribological contacts, revealing orientation-dependent microstructural evolution.

Contribution

It introduces deformation twinning as a novel experimental method to investigate tribological stress states and validates stress field models through microstructural analysis.

Findings

Twinning shows orientation dependence under tribological load.

Neither sliding nor normal crystal directions solely determine twinning.

Deformation twins can effectively probe complex stress fields.

Abstract

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 single-crystalline 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 clearly show a grain orientation dependence of twinning under tribological load. Unexpectedly, neither the crystal direction parallel to the sliding nor the normal direction are solely decisive for twinning. This experimental approach is ideal to experimentally validate tribological stress field models, as is demonstrates here.