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 2.5: Topical Talk

Montag, 1. April 2019, 11:45–12:15, H43

Single-crystal mechanical properties of equiatomic CrMnFeCoNi high-entropy alloy and its derivative equiatomic quaternary and ternary medium-entropy alloys — •Haruyuki Inui — Department of Materials Science and Engineering, Kyoto University, Kyoto, Jpan

The plastic deformation behavior of single crystals of the FCC equatomic CrMnFeCoNi high-entropy alloy and its derivative quaternary (CrFeCoNi) and ternary (CrCoNi) medium-entropy alloys has been investigated in a temperature range of 10-1273 K. Deformation occurs via slip of the {111}<110> system exclusively in the whole temperature range for all alloys investigated. The CRSS values increase with decreasing temperature, especially below room temperature, so that the concept of *stress equivalence* is obeyed for all alloys investigated. This is a clear indication that the strength of these alloys should be described by a mechanism based on solid-solution hardening. The CRSS values at 10 K seems to be well scaled with the mean-square atomic displacement from the regular FCC lattice points (calculated based on density-functional theory). Dislocations are observed to dissociate widely into Shockley partials for all alloys investigated, indicating their low stacking fault energies (below 30 mJ/m2). Deformation twinning occurs in later stages of deformation at low temperatures below room temperature in many of these alloys. The correlation between twinning stress and the stacking-fault energy will be discussed.