TITLE:
Analysis of Deformation in a High Entropy Alloy Using an Internal State Variable Model
AUTHORS:
Aaron Stein, Paul S. Follansbee
KEYWORDS:
High Entropy Alloys, Constitutive Modeling, Strain-Hardening, Deformation, Dynamic Strain Aging
JOURNAL NAME:
Materials Sciences and Applications,
Vol.8 No.6,
June
21,
2017
ABSTRACT: 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.