Relationship between microstructures and mechanical properties of an equiatomic AlCoCrFeNi high-entropy alloy fabricated by electron beam melting

A series of (AlCrTiZrV)-Six-N films with different silicon contents were deposited on monocrystalline silicon substrates by direct-current (DC) magnetron sputtering. The films were characterized by the X-ray diffractometry (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and nano-indentation techniques. The effects of the silicon content on the microstructures and mechanical properties of the films were investigated. The experimental results show that the (AlCrTiZrV)N films grow in columnar grains and present a (200) preferential growth orientation. The addition of the silicon element leads to the disappearance of the (200) peak, and the grain refinement of the (AlCrTiZrV)-Six-N films. Meanwhile, the reticular amorphous phase is formed, thus developing the nanocomposite structure with the nanocrystalline structures encapsulated by the amorphous phase. With the increase of the silicon content, the mechanical properties first increase and then decrease. The maximal hardness and modulus of the film reach 34.3 GPa and 301.5 GPa, respectively, with the silicon content (x) of 8% (volume percent). The strengthening effect of the (AlCrTiZrV)-Six-N film can be mainly attributed to the formation of the nanocomposite structure.

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Microstructures and mechanical properties of the non-equiatomic FeMnNiCoCr high entropy alloy processed by differential speed rolling

Materials Science and Engineering A ◽

10.1016/j.msea.2018.04.106 ◽

2018 ◽

Vol 727 ◽

pp. 38-42 ◽

Cited By ~ 13

Author(s):

H.T. Jeong ◽

W.J. Kim

Keyword(s):

Mechanical Properties ◽

High Entropy Alloy ◽

High Entropy ◽

Differential Speed Rolling ◽

Microstructures And Mechanical Properties ◽

Differential Speed

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Effects of Nb Addition on Microstructures and Mechanical Properties of Nbx-CoCrFeMnNi High Entropy Alloy Films

Coatings ◽

10.3390/coatings11121539 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1539

Author(s):

Yu-Hsuan Liang ◽

Chia-Lin Li ◽

Chun-Hway Hsueh

Keyword(s):

Mechanical Properties ◽

Amorphous Phase ◽

Compressive Yield Strength ◽

High Entropy Alloy ◽

Face Centered Cubic ◽

Compression Tests ◽

Alloy Films ◽

High Entropy ◽

Microstructures And Mechanical Properties ◽

Nb Addition

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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