Effects of torsional deformation on the microstructures and mechanical properties of a CoCrFeNiMo_0.15 high-entropy alloy

Abstract

The effects of torsional deformation on the microstructures and mechanical properties of a CoCrFeNiMo_0.15 high-entropy alloy have been investigated. The torsional deformation generates a gradient microstructure distribution due to the gradient torsional strain. Both dislocation activity and deformation twinning dominated the torsional deformation process. With increasing the torsional equivalent strain, the microstructural evolution can be described as follows: (1) formation of pile-up dislocations parallel to the trace of {1 1 1}-type slip planes; (2) formation of Taylor lattices; (3) formation of highly dense dislocation walls; (3) formation of microbands and deformation twins. The extremely high deformation strain (strained to fracture) results in the activation of wavy slip. The tensile strength is very sensitive to the torsional deformation, and increases significantly with increasing the torsional angle.

Keywords:

• High-entropy alloy
• torsion
• dislocations
• deformation twinning
• mechanical properties

Acknowledgements

The financial supports from Hunan Provincial National Natural Science Foundation of China (2015JJ2206), Fundamental Research Funds for the Central Universities of Central South University (2016zzts267) and the National Natural Science Foundation of China (51671217) are appreciated.