Tailoring mechanical properties of a CoCrNi medium-entropy alloy by controlling nanotwin-HCP lamellae and annealing twins

The microstructure significantly influences the mechanical properties of metals and alloys. Herein, we present a novel approach to tailoring the mechanical properties of a CoCrNi medium-entropy alloy by controlling nanotwin-HCP lamellae and annealing twins. It has been observed that the dislocations...

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2019-01, Vol.744, p.241-246
Main Authors: Deng, H.W., Xie, Z.M., Zhao, B.L., Wang, Y.K., Wang, M.M., Yang, J.F., Zhang, T., Xiong, Y., Wang, X.P., Fang, Q.F., Liu, C.S.
Format: Article
Language:English
Subjects:
Alloys
Annealing
Annealing twins
CoCrNi
Cottrell locking
Deformation mechanisms
Dislocations
Ductility
Entropy
Equal channel angular pressing
High strength
Locks
Mechanical properties
Medium entropy alloys
Medium-entropy alloy
Microstructure
Nanotwin-HCP
Optimization
Recrystallization
Strength
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Summary:The microstructure significantly influences the mechanical properties of metals and alloys. Herein, we present a novel approach to tailoring the mechanical properties of a CoCrNi medium-entropy alloy by controlling nanotwin-HCP lamellae and annealing twins. It has been observed that the dislocations, three-dimensional nanotwins and Lomer-Cottrell locks, induced by equal channel angular pressing, synergistically strengthened the CoCrNi alloy. The nanotwin-HCP composite lamellae, induced by post-deformation annealing at 500 °C, resulted in high strength of 1.5 GPa and a strain of 4.1%. A superior combination of high strength (~ 1 GPa) and excellent ductility (~ 45%) has been obtained by further decorating the microstructure through producing annealing twins in recrystallized micro-sized grains. The present study presents the strengthening mechanisms and provides a generic approach to obtain the desirable mechanical properties of the alloys via microstructural optimization.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2018.11.143