scholarly journals Hexagonal Closed-Packed Precipitation Enhancement in a NbTiHfZr Refractory High-Entropy Alloy

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 485 ◽  
Author(s):  
Yueli Ma ◽  
Shiwei Wu ◽  
Yuefei Jia ◽  
Pengfei Hu ◽  
Yeqiang Bu ◽  
...  
Keyword(s):  
Volume Fraction ◽  
High Strength ◽  
High Entropy Alloy ◽  
Body Centered Cubic ◽  
Ductility Property ◽  
High Entropy ◽  
New Strategy ◽  
Precipitation Enhancement ◽  
Strength And Ductility ◽  
Hexagonal Closed Packed

A NbTiHfZr high-entropy alloy (HEA) with a main phase of body-centered cubic structure is fabricated. Some hexagonal closed-packed (hcp) precipitates are observed in this alloy. A thermal-mechanical process, i.e., cold-rolling followed by annealing, can manipulate the volume fraction of the hcp nano-precipitates that can enhance strength and ductility. The enhancement is tailorable as a function of the volume fraction of the hcp nano-precipitate. The results indicate that the strength-ductility property can be manipulated via adjusting post-deformation heat-treatment methods, which provide a new strategy by utilizing metastability at high-temperature to design high strength refractory HEAs (RHEAs) without lost in ductility.

scholarly journals Prediction of Strength and Ductility in Partially Recrystallized CoCrFeNiTi0.2 High-Entropy Alloy

Entropy ◽  
2019 ◽  
Vol 21 (4) ◽  
pp. 389 ◽  
Author(s):  
Hanwen Zhang ◽  
Peizhi Liu ◽  
Jinxiong Hou ◽  
Junwei Qiao ◽  
Yucheng Wu
Keyword(s):  
Tensile Strength ◽  
Single Phase ◽  
Volume Fraction ◽  
Tensile Elongation ◽  
High Entropy Alloy ◽  
High Entropy Alloys ◽  
Number Density ◽  
High Entropy ◽  
Average Size ◽  
Strength And Ductility

The mechanical behavior of a partially recrystallized fcc-CoCrFeNiTi0.2 high entropy alloys (HEA) is investigated. Temporal evolutions of the morphology, size, and volume fraction of the nanoscaled L12-(Ni,Co)3Ti precipitates at 800 °C with various aging time were quantitatively evaluated. The ultimate tensile strength can be greatly improved to ~1200 MPa, accompanied with a tensile elongation of ~20% after precipitation. The temporal exponents for the average size and number density of precipitates reasonably conform the predictions by the PV model. A composite model was proposed to describe the plastic strain of the current HEA. As a consequence, the tensile strength and tensile elongation are well predicted, which is in accord with the experimental results. The present experiment provides a theoretical reference for the strengthening of partially recrystallized single-phase HEAs in the future.

scholarly journals Effects of Annealing on Microstructure and Mechanical Properties of Metastable Powder Metallurgy CoCrFeNiMo0.2 High Entropy Alloy

Entropy ◽  
2019 ◽  
Vol 21 (5) ◽  
pp. 448 ◽  
Author(s):  
Cui Zhang ◽  
Bin Liu ◽  
Yong Liu ◽  
Qihong Fang ◽  
Wenmin Guo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Volume Fraction ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Large Volume Fraction ◽  
The Matrix ◽  
Coarse Precipitation ◽  
Precipitation Enhancement ◽  
Precipitation Phase

A CoCrFeNiMo0.2 high entropy alloy (HEA) was prepared through powder metallurgy (P/M) process. The effects of annealing on microstructural evolution and mechanical properties of P/M HEAs were investigated. The results show that the P/M HEA exhibit a metastable FCC single-phase structure. Subsequently, annealing causes precipitation in the grains and at the grain boundaries simultaneously. As the temperature increases, the size of the precipitates grows, while the content of the precipitates tends to increase gradually first, and then decrease as the annealing temperature goes up to 1000 °C. As the annealing time is prolonged, the size and content of the precipitates gradually increases, eventually reaching a saturated stable value. The mechanical properties of the annealed alloys have a significant correspondence with the precipitation behavior. The larger the volume fraction and the size of the precipitates, the higher the strength and the lower the plasticity of the HEA. The CoCrFeNiMo0.2 high entropy alloy, which annealed at 800 °C for 72 h, exhibited the most excellent mechanical properties with the ultimate tensile strength of about 850 MPa and an elongation of about 30%. Nearly all of the annealed HEAs exhibit good strength–ductility combinations due to the significant precipitation enhancement and nanotwinning. The separation of the coarse precipitation phase and the matrix during the deformation process is the main reason for the formation of micropores. Formation of large volume fraction of micropores results in a decrease in the plasticity of the alloy.

A new strategy of tailoring strength and ductility of CoCrFeNi based high-entropy alloy

2020 ◽  
Vol 774 ◽  
pp. 138940 ◽  
Author(s):  
Fukai Zheng ◽  
Guannan Zhang ◽  
Xiujuan Chen ◽  
Xiao Yang ◽  
Zengchao Yang ◽  
...  
Keyword(s):  
High Entropy Alloy ◽  
High Entropy ◽  
New Strategy ◽  
Strength And Ductility

L21-strengthened face-centered cubic high-entropy alloy with high strength and ductility

2020 ◽  
Vol 797 ◽  
pp. 140056 ◽  
Author(s):  
Yongliang Qi ◽  
Yake Wu ◽  
Tinghui Cao ◽  
Lin He ◽  
Feng Jiang ◽  
...  
Keyword(s):  
High Strength ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Face Centered ◽  
Strength And Ductility

Corrosion-resistant high entropy alloy with high strength and ductility

2019 ◽  
Vol 166 ◽  
pp. 168-172 ◽  
Author(s):  
S.S. Nene ◽  
M. Frank ◽  
K. Liu ◽  
S. Sinha ◽  
R.S. Mishra ◽  
...  
Keyword(s):  
High Strength ◽  
High Entropy Alloy ◽  
Corrosion Resistant ◽  
High Entropy ◽  
Strength And Ductility

A Si-containing FeCoCrNi high-entropy alloy with high strength and ductility synthesized in situ via selective laser melting

2020 ◽  
Vol 35 ◽  
pp. 101340 ◽  
Author(s):  
Danyang Lin ◽  
Lianyong Xu ◽  
Xiaojie Li ◽  
Hongyang Jing ◽  
Gang Qin ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
High Strength ◽  
High Entropy Alloy ◽  
Laser Melting ◽  
High Entropy ◽  
Strength And Ductility

AlCoCrFeNi high entropy alloy reinforced Cu-based composite with high strength and ductility after hot extrusion

Vacuum ◽  
2021 ◽  
Vol 184 ◽  
pp. 109882
Author(s):  
Yunzi Liu ◽  
Jian Chen ◽  
Zhao Li ◽  
Xianhui Wang ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Hot Extrusion ◽  
High Strength ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Strength And Ductility
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