scholarly journals A EFFECT OF CeO2 DOPING ON THE MICROSTRUCTURE AND CORROSION BEHAVIOR OF CoCuNiTi HIGH-ENTROPY ALLOY COATINGS

2021 ◽  
Vol 55 (6) ◽  
Author(s):  
Mingxing Ma ◽  
Liang Zhao ◽  
Zhi-xin Wang ◽  
Shang-zhi Li ◽  
Chen Dong
Keyword(s):  
Corrosion Behavior ◽  
Phase Structure ◽  
Main Phase ◽  
Molar Ratio ◽  
High Entropy Alloy ◽  
Dual Phase ◽  
Liquid Environment ◽  
High Entropy ◽  
Fcc Phase ◽  
Bcc Phase

CoCuNiTi high-entropy alloy coatings with an equal molar ratio were prepared on 45 steel substrates using the laser-cladding method. The effect of CeO2 doping on phase structure, microstructure and corrosion behavior of CoCuNiTi coatings were investigated by X-ray diffraction, optical microscope, scanning electron microscope, and electrochemical workstation. The results show that the phase structure of CoCuNiTi coating doped with 1 w/% CeO2 is transformed from the original dual-phase structure of FCC main phase and BCC phase to the dual-phase structure of BCC main phase and FCC phase, mainly because CeO2 addition helps to improve the temperature gradient and solidification rate during solidification, reduce the nucleation resistance and the diffusion distance of the alloying elements, and provide a liquid environment with longer time, lower viscosity and higher diffusion rate. The microstructure of the two coatings is composed of BCC-phase dendrite and FCC-phase interdendrite. The widths of the primary dendrites of the columnar dendrites in CoCuNiTi cladding layer before and after CeO2 doping are about 8.10 µm and 6.51 µm, respectively. The CoCuNiTi coating doped with 1 w/% CeO2 has the smallest corrosion current density, the largest capacitive reactance arc radius and polarization resistance, and the best corrosion resistance in 3.5 w/% NaCl solution, which is mainly due to making the alloy structure refined and the element distribution uniform after the CeO2 addition.

scholarly journals Effects of Cr Content on Microstructure and Mechanical Properties of AlCoCrxFeNi High-Entropy Alloy

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Tao-Tsung Shun ◽  
Wei-Jhe Hung
Keyword(s):  
Mechanical Properties ◽  
Molar Ratio ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Cr Content ◽  
Microstructure And Mechanical Properties ◽  
Alloy Hardness ◽  
Fcc Phase ◽  
Bcc Phase ◽  
Feni Alloys

In this study, we investigated the effects of Cr content on the crystal structure, microstructure, and mechanical properties of four AlCoCrxFeNi (x = 0.3, 0.5, 0.7, and 1.0, in molar ratio) high-entropy alloys. AlCoCr0.3FeNi alloy contains duplex phases, which are ordered BCC phase and FCC phase. As the Cr content increases to x = 1.0, the FCC phase disappears and the microstructure exhibits a spinodal structure formed by a BCC phase and an ordered BCC phase. This result indicates that Cr is a BCC former in AlCoCrxFeNi alloys. With increasing Cr content, the alloy hardness increases from HV415 to HV498. AlCoCr0.3FeNi, AlCoCr0.5FeNi, and AlCoCr0.7FeNi exhibit a high compressive fracture strain of about 0.24 because of the formation of the FCC phase in the BCC matrix. Moreover, the highest yield stress of 1394 MPa and compressive strength of 1841 MPa presented by AlCoCrFeNi alloy are due to the existence of a nano-net-like spinodal structure.

Effect of Mn Contents on the Phase Transition of the High Entropy Alloy Prepared by Laser Cladding

2016 ◽  
Vol 849 ◽  
pp. 64-70 ◽  
Author(s):  
Shi Da Liu ◽  
Cun Yuan Peng ◽  
Ming Xing Ma ◽  
Wen Jin Liu ◽  
Wei Ming Zhang
Keyword(s):  
Phase Transition ◽  
Laser Cladding ◽  
Phase Structure ◽  
Steel Substrate ◽  
High Hardness ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Two Phases ◽  
Fcc Phase ◽  
Bcc Phase

Al1.3FeCoNiCuCr high entropy alloy (HEA) coatings were prepared by pre-placed laser cladding on 921A steel substrate, and the study on the phase transition of the Al1.3FeCoNiCuCr coating due to the introduction of Mn was conducted. The combination of TEM and XRD results showed that the Al1.3FeCoNiCuCr HEA coatings without Mn addition typically consisted of two kinds of grains, i.e., one is composed of only FCC phase, and the another is a mixture of BCC and FCC phases. The two phases were of similar ratio in the coatings, while nanoparticulate precipitates were observed in the bcc phase. When 3 wt. % Mn was introduced into the alloy, the coatings consisted of also FCC and BCC phase. However, most of the grains were in FCC phase, while the BCC phase with a lath shape only distributed between the FCC phases. High hardness nanobanded precipitates were observed in the FCC phase. It is clearly revealed that the phase structure of Al1.3FeCoNiCuCr coatings undergoes a dramatic transition due to the introducing of Mn.

Phase Transition of As-Milled and Annealed CrCuFeMnNi High-Entropy Alloy Powder

NANO ◽  
2018 ◽  
Vol 13 (09) ◽  
pp. 1850100 ◽  
Author(s):  
Rui-Feng Zhao ◽  
Bo Ren ◽  
Guo-Peng Zhang ◽  
Zhong-Xia Liu ◽  
Jian-Jian Zhang
Keyword(s):  
Phase Transition ◽  
Solution Structure ◽  
Milling Time ◽  
Structure Evolution ◽  
High Entropy Alloy ◽  
Chemical Homogeneity ◽  
High Entropy ◽  
Dynamic Phase Transition ◽  
Fcc Phase ◽  
Bcc Phase

The CrCuFeMnNi high entropy alloy (HEA) powder was synthesized by mechanical alloying. The effects of milling time and subsequent annealing on the structure evolution, thermostability and magnetic property were investigated. After 50[Formula: see text]h of milling, the CrCuFeMnNi HEA powder consisted of a major FCC phase and a small amount of BCC phase. The crystallite size and strain lattice of 50[Formula: see text]h-ball-milled CrCuFeMnNi HEA powder were 12[Formula: see text]nm and 1.02%, respectively. The powder exhibited refined morphology and excellent chemical homogeneity. The supersaturated solid solution structure of the as-milled HEA powder transformed into FCC1, FCC2, a small amount of BCC and [Formula: see text] phase in annealed state. Most of the BCC phase decomposed into FCC (mainly FCC2 phase) and [Formula: see text] phases, and the dynamic phase transition was almost in equilibrium at 900[Formula: see text]C. The saturated magnetization and coercivity force of the 50[Formula: see text]h-ball-milled CrCuFeMnNi HEA powder were respectively 16.1[Formula: see text]emu/g and 56.2[Formula: see text]Oe.

Novel Fe36Mn21Cr18Ni15Al10 high entropy alloy with bcc/B2 dual-phase structure

2017 ◽  
Vol 705 ◽  
pp. 756-763 ◽  
Author(s):  
D.G. Shaysultanov ◽  
G.A. Salishchev ◽  
Yu.V. Ivanisenko ◽  
S.V. Zherebtsov ◽  
M.A. Tikhonovsky ◽  
...  
Keyword(s):  
Phase Structure ◽  
High Entropy Alloy ◽  
Dual Phase ◽  
High Entropy

Effect of the Annealing Treatment on the Microstructure, Microhardness and Corrosion Behaviour of Al0.3CrFe1.5MnNi0.5 High-Entropy Alloys

2013 ◽  
Vol 748 ◽  
pp. 79-85 ◽  
Author(s):  
L.C. Tsao ◽  
C.S. Chen ◽  
Kuo Huan Fan ◽  
Yen Teng Huang
Keyword(s):  
Corrosion Behaviour ◽  
Dendritic Structure ◽  
Annealing Treatment ◽  
Age Hardening ◽  
High Entropy Alloy ◽  
Second Phase ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Fcc Phase ◽  
Bcc Phase

In this study, an Al0.3CrFe1.5MnNi0.5high entropy alloy was synthesized by arc-melting in Ar. The as-cast alloy ingot was heat treated for 8 h at 650-750°C and then cooled in furnace to investigate the effects of age treatment on the microstructure, hardness and corrosion behaviour. The microstructure of as-cast sample has a typical rich-Cr BCC structure of dendrites, rich-Ni FCC interdendrite phases and a small fraction of cross-like rich-Ni FCC phase within the majority dendritic structure. During annealing treatment at 650°C, the cross-like FCC phase (β-FCC) gradually decreased, dendritic rich-Cr BCC phase transfers to Cr5Fe6Mn8phase, and the AlNi phase precipitated within the matrix dendrites. The interdendritic β1-FCC phases gradually decomposed and transfers to second-phase (β2FCC), and the AlNi precipitated phase coarsen during annealing at 750°C. In addition, Cr5Fe6Mn8phase gradually transfers to rich-Cr BCC phase during slow-cooling process. These precipitation phases in the grain matrix are the main age hardening mechanism. The potentiodynamic polarization of the Al0.3CrFe1.5MnNi0.5high entropy alloys, obtained in 3.5% NaCl solutions, clearly revealed that the corrosion resistance increases and the passive region decreases as annealing temperature increasing.

scholarly journals Age Heat Treatment of Al0.5CoCrFe1.5NiTi0.5 High-Entropy Alloy

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 91
Author(s):  
Che-Fu Lee ◽  
Tao-Tsung Shun
Keyword(s):  
Cast Alloy ◽  
Dendritic Structure ◽  
Age Hardening ◽  
High Entropy Alloy ◽  
Σ Phase ◽  
High Entropy ◽  
The Matrix ◽  
B2 Phase ◽  
Fcc Phase ◽  
Bcc Phase

In this study, Al0.5CoCrFe1.5NiTi0.5 high-entropy alloy was heat-treated from 500 °C to 1200 °C for 24 h to investigate age-hardening phenomena and microstructure evolution. The as-cast alloy, with a hardness of HV430, exhibited a dendritic structure comprising an (Fe,Cr)-rich FCC phase and a (Ni,Al,Ti)-rich B2 phase, and the interdendrite exhibited a spinodal decomposed structure comprising an (Fe,Cr)-rich BCC phase and a (Ni,Al,Ti)-rich B2 phase. Age hardening and softening occurred at 500 °C to 800 °C and 900 °C to 1100 °C, respectively. We observed optimal age hardening at 700 °C, and alloy hardness increased to HV556. The hardening was attributed to the precipitation of the σ phase, and the softening was attributed to the dissolution of the σ phase back into the matrix and coarsening of the microstructure. The appearance of fine Widmanstätten precipitates formed by the (Al,Ti)-rich BCC phase and (Ni,Al,Ti)-rich B2 phase at 1200 °C led to secondary hardening.

Effect of Cold Rolling on the Microstructure and Hardness of Al5Cr12Fe35Mn28Ni20 High Entropy Alloy

2018 ◽  
Vol 917 ◽  
pp. 241-245 ◽  
Author(s):  
Sally Elkatatny ◽  
Mohamed Abdel Hady Gepreel ◽  
Atef Hamada
Keyword(s):  
Cold Rolling ◽  
Phase Structure ◽  
Rolling Reduction ◽  
High Entropy Alloy ◽  
High Entropy Alloys ◽  
Characterization Methods ◽  
High Entropy ◽  
Cold Rolling Reduction ◽  
Fcc Phase ◽  
Dendritic Structures

The microstructure and hardness changes of a non-equiatomic Al5Cr12Fe35Mn28Ni20high-entropy-alloys (HEA) with cold rolling are presented here. Using a variety of characterization methods, it is shown that the alloy is single FCC phase structure which doesn't change with cold rolling up to90%CR. With increasing the cold rolling reduction ratio, the hardness increased and the dendritic structures are broken and refined.

Sign in / Sign up

Export Citation Format

Share Document