Author(s)

Aaron Stein¹, Paul S. Follansbee²

¹Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA.
²Boyer School of Natural Sciences, Mathematics, and Computing, Saint Vincent College, Latrobe, PA, USA.

Deformation in the model high entropy alloy CoCrFeMnNi is assessed using an internal state variable constitutive model. A remarkable property of these alloys is the extraordinarily high strain hardening rates they experience in the plastic region of the stress strain curve. Published stress-strain measurements over a range of temperatures are analyzed. Dislocation obstacle interactions and the observed high rate of strain hardening are characterized in terms of state variables and their evolution. A model that combines a short-range obstacle and a long-range obstacle is shown to match experimental measurements over a wide range of temperatures and grain sizes. The long-range obstacle is thought to represent interactions of dislocations with regions of incomplete mixing or partial segregation. Dynamic strain aging also is observed at higher temperatures. Comparisons with measurements in austenitic stainless steel show some common trends.

High Entropy Alloys, Constitutive Modeling, Strain-Hardening, Deformation, Dynamic Strain Aging

Stein, A. and Follansbee, P. (2017) Analysis of Deformation in a High Entropy Alloy Using an Internal State Variable Model. Materials Sciences and Applications, 8, 484-492. doi: 10.4236/msa.2017.86033.