Regensburg 2019 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 2: Topical session (Symposium MM): High entropy and compositionally complex alloys

MM 2.9: Vortrag

Montag, 1. April 2019, 13:00–13:15, H43

On the mechanism of displacive phase transformation in metastable high entropy alloys — •Jing Su, Dierk Raabe, and Zhiming Li — Max-Planck-Institut für Eisenforschung GmbH, Dusseldorf, Germany

High-entropy alloys (HEAs) have drawn increasing attention in the past decade due to their massive solid-solution compositional space and promising mechanical properties. Recently, non-equiatomic metastable HEAs with tunable stacking fault energy have shown improved mechanical properties with an even larger compositional freedom and a broader range for microstructure design compared to the equiatomic stable HEAs. This is related to the joint activation of multiple deformation mechanisms including transformation induced plasticity (TRIP) and/or twinning induced plasticity (TWIP). In the current study, a metastable interstitial carbon-doped HEA (iHEA) has been chosen and subjected to cold rolling. Interestingly, deformation-driven forward and reverse (bidirectional) martensitic transformation has been observed in the current iHEA with a well-tuned stacking fault energy. The mechanisms of such bidirectional displacive transformation and the associated nanostructure formation have been investigated by electron channeling contrast imaging (ECCI), electron backscattered diffraction (EBSD) and high-resolution transmission electron microscopy (HR-TEM). We also discuss the mechanical properties of the nanostructured specimens and the corresponding work hardening behavior to shed light on the design of strong and ductile bulk nanostructured HEAs via displacive transformation.