Orientation dependence and asymmetry of the mechanical behavior of (CoCrFeNi)94Ti2Al4 high-entropy alloy single crystals

2020 ◽  
Author(s):  
A. A. Saraeva ◽  
Z. V. Pobedennaya ◽  
I. V. Kireeva ◽  
Yu. I. Chumlyakov
Keyword(s):  
Mechanical Behavior ◽  
Single Crystals ◽  
Orientation Dependence ◽  
High Entropy Alloy ◽  
High Entropy

scholarly journals High-Strength Behavior of the Al0.3CoCrFeNi High-Entropy Alloy Single Crystals

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1149
Author(s):  
Irina V. Kireeva ◽  
Yuriy I. Chumlyakov ◽  
Zinaida V. Pobedennaya ◽  
Anna V. Vyrodova ◽  
Anastasia A. Saraeva
Keyword(s):  
Single Crystals ◽  
Yield Point ◽  
Stress Level ◽  
High Stress ◽  
High Strength ◽  
Orientation Dependence ◽  
Temperature Deformation ◽  
High Entropy Alloy ◽  
Shear Stresses ◽  
High Entropy

The main disadvantage of fcc (face-centred cubic lattice) high-entropy alloys is the low stress level at the yield point (σ0.1) at a test temperature above room temperature. This restricts their practical application at high test temperatures from 773 K to 973 K. In this study, we found that a high stress level was reached at the yield point σ0.1 ≈ G/100–G/160 (G is the shear modulus) of the [001]- and [1¯44]-oriented crystals of the Co23.36Cr23.29Fe23.80Ni21.88Al7.67 (Al0.3CoCrFeNi) high-entropy alloy (HEA) within a wide temperature range of 77–973 K under tension, due to the occurrence, of nanotwins, multipoles, dislocations under plastic deformation at 77 K and the subsequent precipitation of ordered L12 and B2 particles. It was shown that grain boundaries are not formed and the samples remain in a single-crystal state after low-temperature deformation and subsequent ageing at 893 K for 50 h. Achieving a high-strength state in the Al0.3CoCrFeNi HEA single crystals induces the orientation dependence of the critical resolved shear stresses (τcr) at T ≥ 200 K (τcr[1¯44] > τcr[001]), which is absent in the initial single-phase crystals, weakens the temperature dependence of σ0.1 above 573 K, and reduces plasticity to 5–13% in the [1¯44] orientation and 15–20% in the [001] orientation.

Temperature and Orientation Dependence of the Mechanical Properties of Al0.3CoCrFeNi High-Entropy Alloy Single Crystals Hardened by Non-Coherent β- Phase Particles

2020 ◽  
Vol 63 (1) ◽  
pp. 134-141 ◽  
Author(s):  
I. V. Kireeva ◽  
Yu. I. Chumlyakov ◽  
Z. V. Pobedennaya ◽  
A. V. Vyrodova ◽  
A. A. Saraeva ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Single Crystals ◽  
Orientation Dependence ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Β Phase

The orientation dependence of critical shear stresses in Al0.3CoCrFeNi high-entropy alloy single crystals

2017 ◽  
Vol 43 (7) ◽  
pp. 615-618 ◽  
Author(s):  
I. V. Kireeva ◽  
Yu. I. Chumlyakov ◽  
Z. V. Pobedennaya ◽  
A. V. Vyrodova ◽  
I. V. Kuksgauzen ◽  
...  
Keyword(s):  
Single Crystals ◽  
Orientation Dependence ◽  
High Entropy Alloy ◽  
Shear Stresses ◽  
High Entropy

scholarly journals EFFECT OF γ′-PHASE PARTICLES ON THE MECHANICAL BEHAVIOR AND DEFORMATION MECHANISM OF (CoCrFeNi)94Ti2Al4 HIGH ENTROPY ALLOY SINGLE CRYSTALS

2021 ◽  
pp. 84-90
Author(s):  
A. A. Saraeva ◽  
Keyword(s):  
Mechanical Behavior ◽  
Strain Hardening ◽  
Single Crystals ◽  
Yield Point ◽  
Volume Fraction ◽  
High Entropy Alloy ◽  
Strong Temperature Dependence ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Hardening Coefficient

Recently, the interest of researchers has focused on a new FCC class (FCC – face-centered cubic lattice) high-entropy alloys (HEA), due to their unique properties – high values of the strain hardening coefficient, good plasticity, and ductile fracture at low test temperatures. Such a combination of properties in an FCC of HEA is achieved by mixing five or more elements in equal atomic proportions. Due to the strong temperature dependence of stresses at the σ0.1(T) yield point, these alloys have low σ0.1 values at temperatures above room temperature, which hinders their practical application. A precipitation hardening is an effective way to achieve high strength and is successfully used for hardening HEA FCC. The paper studied the influence of ageing at 923 K for 4 hours and at 1073 K for 18 and 30 hours on the mechanical behavior of single crystals of (CoCrFeNi)94Ti2Al4 (at.%) HEA FCC oriented along the [001] direction under tension. Ageing at 923 K for 4 hours and at 1073 K for 18 and 30 hours leads to the precipitation of γ′-phase particles, the size and volume fraction of which depend on the ageing temperature and time. The γ′-phase particles precipitation leads to an increase in stresses at the yield point from 47 MPa (ageing at 923 K, 4 hours) to 226 MPa (ageing at 1073 K, 30 hours) relative to quenched crystals at 296 K. The study identified the dependence of the strain hardening coefficient, plasticity, and the maximum stress level before fracture on heat treatment. The author discussed the reasons for the growth of stresses at the yield point and the strain hardening coefficient upon precipitation of γ′-phase particles.

Orientation dependence of twinning in single crystalline CoCrFeMnNi high-entropy alloy

2017 ◽  
Vol 705 ◽  
pp. 176-181 ◽  
Author(s):  
I.V. Kireeva ◽  
Yu.I. Chumlyakov ◽  
Z.V. Pobedennaya ◽  
I.V. Kuksgausen ◽  
I. Karaman
Keyword(s):  
Orientation Dependence ◽  
High Entropy Alloy ◽  
Single Crystalline ◽  
High Entropy
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