Effects of Nb addition on structural evolution and properties of the CoFeNi2V0.5 high-entropy alloy

In the present work, Nbx-CoCrFeMnNi high entropy alloy films (HEAFs, 0 to 7.2 at.% Nb) were fabricated by radio frequency (RF) magnetron co-sputtering of CoCrFeMnNi alloy and Nb targets. The effects of Nb addition on the microstructures and mechanical properties of HEAFs were systematically investigated. For Nb-free film (0 at.% Nb), the face-centered cubic (FCC) peaks were identified in the X-ray diffraction (XRD) pattern. The addition of Nb resulted in a broadening of diffraction peaks, a decrease in peak intensity, and the vanishment of high-angle peaks. Transmission electron microscope (TEM) images indicated the formation of nanotwins at low Nb concentrations, and a transition from a single phase FCC solid solution to an amorphous phase was observed with the increasing Nb concentration. The films were strengthened with an increase in Nb concentration. Specifically, the hardness characterized by nanoindentation increased from 6.5 to 8.1 GPa. The compressive yield strength and fracture strength measured from micropillar compression tests were improved from 1.08 GPs and 2.56 GPa to 2.70 GPa and 5.76 GPa, respectively, whereas the fracture strain decreased from >29.4% (no fracture) to 15.8%. Additionally, shear banding was observed in the presence of amorphous phase.

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Structural evolution in TiZrHfNb high-entropy alloy

Materialia ◽

10.1016/j.mtla.2021.101311 ◽

2022 ◽

pp. 101311

Author(s):

R.E. Ryltsev ◽

S.Kh. Estemirova ◽

V.S. Gaviko ◽

D.A. Yagodin ◽

V.A. Bykov ◽

...

Keyword(s):

Structural Evolution ◽

High Entropy Alloy ◽

High Entropy

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Deformation-induced crystalline-to-amorphous phase transformation in a CrMnFeCoNi high-entropy alloy

Science Advances ◽

10.1126/sciadv.abe3105 ◽

2021 ◽

Vol 7 (14) ◽

pp. eabe3105

Author(s):

Hao Wang ◽

Dengke Chen ◽

Xianghai An ◽

Yin Zhang ◽

Shijie Sun ◽

...

Keyword(s):

Phase Transformation ◽

Amorphous Phase ◽

Structural Evolution ◽

Crack Tip ◽

Dislocation Slip ◽

High Entropy Alloy ◽

Face Centered Cubic ◽

High Entropy ◽

Dislocation Glide ◽

Ultrafine Grained

The Cantor high-entropy alloy (HEA) of CrMnFeCoNi is a solid solution with a face-centered cubic structure. While plastic deformation in this alloy is usually dominated by dislocation slip and deformation twinning, our in situ straining transmission electron microscopy (TEM) experiments reveal a crystalline-to-amorphous phase transformation in an ultrafine-grained Cantor alloy. We find that the crack-tip structural evolution involves a sequence of formation of the crystalline, lamellar, spotted, and amorphous patterns, which represent different proportions and organizations of the crystalline and amorphous phases. Such solid-state amorphization stems from both the high lattice friction and high grain boundary resistance to dislocation glide in ultrafine-grained microstructures. The resulting increase of crack-tip dislocation densities promotes the buildup of high stresses for triggering the crystalline-to-amorphous transformation. We also observe the formation of amorphous nanobridges in the crack wake. These amorphization processes dissipate strain energies, thereby providing effective toughening mechanisms for HEAs.

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Structural evolution and dislocation behaviour study during nanoindentation of Mo20W20Co20Ta20Zr20 high entropy alloy coated Ni single crystal using molecular dynamic simulation

Molecular Simulation ◽

10.1080/08927022.2019.1566606 ◽

2019 ◽

Vol 45 (7) ◽

pp. 572-584 ◽

Cited By ~ 1

Author(s):

Dinesh Kumar Mishra ◽

Md. Meraj ◽

S. K. BadJena ◽

Snehanshu Pal

Keyword(s):

Single Crystal ◽

Molecular Dynamic Simulation ◽

Molecular Dynamic ◽

Dynamic Simulation ◽

Structural Evolution ◽

High Entropy Alloy ◽

High Entropy ◽

Dislocation Behaviour ◽

Behaviour Study

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Effect of Nb addition on the structure and mechanical behaviors of CoCrCuFeNi high-entropy alloy coatings

Surface and Coatings Technology ◽

10.1016/j.surfcoat.2013.12.053 ◽

2014 ◽

Vol 240 ◽

pp. 184-190 ◽

Cited By ~ 76

Author(s):

J.B. Cheng ◽

X.B. Liang ◽

B.S. Xu

Keyword(s):

High Entropy Alloy ◽

Mechanical Behaviors ◽

High Entropy ◽

Nb Addition

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Effect of Ta Addition on Structural Evolution and Mechanical Properties of the CoFeNi2W0.5 High Entropy Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.849.34 ◽

2016 ◽

Vol 849 ◽

pp. 34-39 ◽

Cited By ~ 3

Author(s):

Li Jiang ◽

Yong Dong ◽

Hui Jiang ◽

Yi Ping Lu ◽

Zhi Qiang Cao ◽

...

Keyword(s):

Mechanical Properties ◽

Vickers Hardness ◽

Solution Structure ◽

Structural Evolution ◽

Alloy System ◽

High Entropy Alloy ◽

Face Centered Cubic ◽

High Entropy ◽

Microstructure And Mechanical Properties ◽

Electron Microscopes

A series of CoFeNi2W0.5Tax (x = 0-0.6) high entropy alloys (HEAs) were synthesized by arc melting to investigate the alloying effect of Ta element on the microstructure and mechanical properties of the CoFeNi2W0.5 alloy system. Phase constitution, microstructure and mechanical properties of the alloys were analyzed by X-ray diffraction (XRD), scanning electron microscopes (SEM), Vickers hardness and compressive test. It was found that when x = 0, the alloy consists of a single-phase face-centered cubic (FCC) solid solution structure and exhibit excellent ductility, the compressive plastic elongation of which can reach 80% without fracture. While with increasing Ta content, the brittle Co2Ta-type Laves phase appears which leads to a decrease of the plastic strain and an increase of the yield strength, and the Vickers hardness shows an obvious increase from HV 179.5 to HV 753.2.

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