Mitigation of strength-ductility trade-off of CoCrNi medium entropy alloys with heterogenous structure by controlled Gd addition and annealing
Journal
Materials Science and Engineering: A
Journal Volume
902
ISSN
0921-5093
Date Issued
2024-06
Author(s)
Yi-Siang Lin
DOI
10.1016/j.msea.2024.146630
Abstract
In this work, we synthesized a series of (CoCrNi)100–xGdx (x = 0/0.3/0.5/1.0) medium entropy alloys (MEAs) using arc melting followed by homogenization, hot-rolling, and annealing at 700, 800, and 900 °C for 1 h. The effects of Gd content and annealing temperature on the microstructures and mechanical properties of Gd-doped CoCrNi MEAs were investigated. The heterogenous microstructure, consisting of the deformed grains, recrystallized grains and precipitates of GdNi5 phase, was obtained in the present study and it exhibited an excellent combination of strength and ductility. The optimum mechanical properties were obtained for CoCrNi MEA with 0.3–0.5 at.% Gd addition and annealed at 700 °C for 1 h to yield the heterogenous microstructure in the present study, and it had the tensile strength of ∼1.3 GPa and fracture strain of 30–40%. The synergetic hardening mechanisms included solid solution, precipitation, grain refinement, nanotwinning and pre-existing dislocation hardening. The relations among compositions, microstructures and mechanical properties of (CoCrNi)100–xGdx MEAs were addressed.
Subjects
Annealing
Arc melting
Mechanical properties
Medium entropy alloys
Microstructure
Nanoindentation
Publisher
Elsevier BV
Type
journal article