Growth Kinetics of Σ-Phase Precipitates and Underlying Diffusion Processes in Crmnfeconi High-Entropy Alloys

2020 ◽  
Author(s):  
G. Laplanche
Keyword(s):  
Growth Kinetics ◽  
Diffusion Processes ◽  
High Entropy Alloys ◽  
Σ Phase ◽  
High Entropy ◽  
Kinetics Of

scholarly journals Phase stability and kinetics of σ-phase precipitation in CrMnFeCoNi high-entropy alloys

2018 ◽  
Vol 161 ◽  
pp. 338-351 ◽  
Author(s):  
G. Laplanche ◽  
S. Berglund ◽  
C. Reinhart ◽  
A. Kostka ◽  
F. Fox ◽  
...  
Keyword(s):  
Phase Stability ◽  
High Entropy Alloys ◽  
Phase Precipitation ◽  
Σ Phase ◽  
High Entropy ◽  
Kinetics Of

scholarly journals The Effect of Al on the Formation of a CrTaO4 Layer in Refractory High Entropy Alloys Ta-Mo-Cr-Ti-xAl

2021 ◽  
Author(s):  
S. Schellert ◽  
B. Gorr ◽  
H.- J. Christ ◽  
C. Pritzel ◽  
S. Laube ◽  
...  
Keyword(s):  
Mass Gain ◽  
Positive Influence ◽  
High Entropy Alloys ◽  
Oxide Scales ◽  
Temperature Oxidation ◽  
Internal Corrosion ◽  
High Entropy ◽  
Continuous Mass ◽  
Oxide Substrate ◽  
Kinetics Of

AbstractIn this study, the effect of Al on the high temperature oxidation of Al-containing refractory high entropy alloys (RHEAs) Ta-Mo-Cr-Ti-xAl (x = 5; 10; 15; 20 at%) was examined. Oxidation experiments were performed in air for 24 h at 1200 °C. The oxidation kinetics of the alloy with 5 at% Al is notably affected by the formation of gaseous MoO3 and CrO3, while continuous mass gain was detected for alloys with the higher Al concentrations. The alloys with 15 and 20 at% Al form relatively thin oxide scales and a zone of internal corrosion due to the formation of dense CrTaO4 scales at the interface oxide/substrate. The alloys with 5 and 10 at% Al exhibit, on the contrary, thick and porous oxide scales because of fast growing Ta2O5. The positive influence of Al on the formation of Cr2O3 followed by the growth of CrTaO4 to yield a compact scale is explained by getter and nucleation effects.

scholarly journals Thermodynamics and Kinetics of High-Entropy Alloys

2021 ◽  
Author(s):  
Michael C. Gao ◽  
Raymundo Arróyave ◽  
John E. Morral ◽  
Ursula R. Kattner
Keyword(s):  
High Entropy Alloys ◽  
High Entropy ◽  
Thermodynamics And Kinetics ◽  
Kinetics Of

Grain growth kinetics in CoCrFeNi and CoCrFeMnNi high entropy alloys processed by spark plasma sintering

2019 ◽  
Vol 791 ◽  
pp. 1114-1121 ◽  
Author(s):  
M. Vaidya ◽  
Ameey Anupam ◽  
J. Vijay Bharadwaj ◽  
Chandan Srivastava ◽  
B.S. Murty
Keyword(s):  
Grain Growth ◽  
Spark Plasma Sintering ◽  
Growth Kinetics ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Grain Growth Kinetics

scholarly journals Effect of Molybdenum Additives on Corrosion Behavior of (CoCrFeNi)100−xMox High-Entropy Alloys

Entropy ◽  
2018 ◽  
Vol 20 (12) ◽  
pp. 908 ◽  
Author(s):  
Wenrui Wang ◽  
Jieqian Wang ◽  
Honggang Yi ◽  
Wu Qi ◽  
Qing Peng
Keyword(s):  
Corrosion Behavior ◽  
Compressive Strain ◽  
Compressive Yield Strength ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
Σ Phase ◽  
High Entropy ◽  
Passivation Film ◽  
Face Centered ◽  
Mo Content

The present work investigates the influence of micro-alloyed Mo on the corrosion behavior of (CoCrFeNi)100−xMox high-entropy alloys. All of the (CoCrFeNi)100−xMox alloys exhibit a single face-centered cubic (FCC) solid solution. However, the (CoCrFeNi)97Mo3 alloy exhibits an ordered sigma (σ) phase enriched in Cr and Mo. With the increase of x (the Mo content) from 1 to 3, the hardness of the (CoCrFeNi)100−xMox alloys increases from 124.8 to 133.6 Vickers hardness (HV), and the compressive yield strength increases from 113.6 MPa to 141.1 MPa, without fracture under about a 60% compressive strain. The potentiodynamic polarization curve in a 3.5% NaCl solution indicates that the addition of Mo has a beneficial effect on the corrosion resistance to some certain extent, opposed to the σ phase. Furthermore, the alloys tend to form a passivation film in the 0.5 M H2SO4 solution in order to inhibit the progress of the corrosion reaction as the Mo content increases.

scholarly journals Effect of Annealing on Microstructure and Mechanical Properties of Al0.5CoCrFeMoxNi High-Entropy Alloys

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 812 ◽  
Author(s):  
Yan-Xin Zhuang ◽  
Xiu-Lan Zhang ◽  
Xian-Yu Gu
Keyword(s):  
Mechanical Properties ◽  
Annealing Temperature ◽  
High Entropy Alloys ◽  
Obvious Effect ◽  
Σ Phase ◽  
High Entropy ◽  
Phase Constituent ◽  
Microstructure And Mechanical Properties ◽  
Bcc Phase ◽  
Good Agreement

The effect of annealing temperature on the microstructure, phase constituents and mechanical properties of Al0.5CoCrFeMoxNi high-entropy complex alloys has been investigated at a fixed annealing time (10 h). The 600 °C-annealing has no obvious effect on their microstructures, while the annealing at 800–1200 °C enhances the precipitation of (Al,Ni)-rich ordered BCC phase or/and (Cr,Mo)-rich σ phase, and thereby greatly affects the microstructure and mechanical properties of the alloys. All the annealed Al0.5CoCrFeNi alloys are composed of FCC and (Al,Ni)-rich ordered BCC phases; the phase constituent of the Al0.5CoCrFeMo0.1Ni alloy changes from FCC + BCC (600 °C) to FCC + BCC + σ (800 °C) and then to FCC + BCC (1100 °C); the phase constituents of the Al0.5CoCrFeMo0.2Ni and Al0.5CoCrFeMo0.3Ni alloys change from FCC + BCC + σ to FCC + BCC with the annealing temperature rising from 600 to 1200 °C; while all the annealed Al0.5CoCrFeMo0.4Ni and Al0.5CoCrFeMo0.5Ni alloys consist of FCC, BCC and σ phases. The phase constituents of most of the alloys investigated are in good agreement with the calculated results from Thermo-Calc program. The alloys annealed at 800 °C under current investigation conditionshave relative fine precipitations and microstructure, and thereby higher hardness and yield stress.

scholarly journals Kinetic ways of tailoring phases in high entropy alloys

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Feng He ◽  
Zhijun Wang ◽  
Yiyan Li ◽  
Qingfeng Wu ◽  
Junjie Li ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Equilibrium Phase ◽  
High Entropy Alloys ◽  
Kinetic Effect ◽  
Phase Selection ◽  
High Entropy ◽  
Comprehensive Performance ◽  
Sluggish Diffusion ◽  
Kinetics Of ◽  
Theoretical Analyses

Abstract The comprehensive performance of high entropy alloys (HEAs) depends on the phase selection significantly. However, up to now, investigations of the phase selection in HEAs mainly focused on the thermodynamic equilibrium phase, while kinetic ways of tailoring the phases in HEAs are seldom considered. In HEAs, the kinetics of sluggish diffusion and the numerous possible phases make the kinetics of phase transformation more complex and intriguing. Here, the kinetic effect in CoCrFeNiTi0.4 HEAs was investigated to reveal the possibility of controlling phase selection via kinetic ways for HEAs. The σ, γ′ and R phases in the CoCrFeNiTi0.4 HEA can be controlled under different cooling rate both in solidification and solid transformation. The theoretical analyses revealed the kinetic effect on phase selection. The method proposed here, tailoring the phases with different kinetic ways, could be used to prepare promising HEAs with very rich composition design.

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