scholarly journals Effects of the Replacement of Co with Ni on the Microstructure, Mechanical Properties, and Age Hardening of AlCo1−xCrFeNi1+x High-Entropy Alloys

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2665
Author(s):  
Che-Fu Lee ◽  
Tao-Tsung Shun
Keyword(s):  
Mechanical Properties ◽  
Fracture Strain ◽  
Dendritic Structure ◽  
Age Hardening ◽  
Molar Ratio ◽  
High Entropy Alloys ◽  
Σ Phase ◽  
High Entropy ◽  
Fcc Phase ◽  
Bcc Phase

In this study, effects of the replacement of Co with Ni on the microstructure, mechanical properties, and age hardening of high-entropy alloys of AlCo1−xCrFeNi1+x (x = molar ratio; x = 0, 0.5, 1, denoted as X0, X0.5, and X1, respectively) were investigated. These three alloys exhibited a dendritic structure comprising an ordered BCC matrix, a BCC phase, and an FCC or an ordered FCC phase. From X0 to X1 alloys, the yield stress and compressive stress decreased from 1202 and 1790 MPa to 693 and 1537 MPa, respectively. However, fracture strain increased from 0.15 to 0.42. Peak age hardening at 600 °C for the X0 alloy was due to the precipitation of the (Cr,Fe)-rich σ phase. Peak age hardening for the X0.5 and X1 alloys was observed at 500 °C because of the precipitation of the σ phase and BCC phase, respectively.

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.

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 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.

scholarly journals Magnetic Properties and Microstructure of FeCoNi(CuAl)0.8Snx (0 ≤ x ≤ 0.10) High-Entropy Alloys

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 872 ◽  
Author(s):  
Zhong Li ◽  
Chenxu Wang ◽  
Linye Yu ◽  
Yong Gu ◽  
Minxiang Pan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
High Tc ◽  
Soft Magnets ◽  
High Entropy ◽  
Face Centered ◽  
Fcc Phase ◽  
Bcc Phase ◽  
Curie Temperatures

The present work exhibits the effects of Sn addition on the magnetic properties and microstructure of FeCoNi(CuAl)0.8Snx (0 ≤ x ≤ 0.10) high-entropy alloys (HEAs). The results show all the samples consist of a mixed structure of face-centered-cubic (FCC) phase and body-centered-cubic (BCC) phase. The addition of Sn promotes the formation of BCC phase, and it also affects the shape of Cu-rich nano-precipitates in BCC matrix. It also shows that the Curie temperatures (Tc) of the FCC phase and the saturation magnetization (Ms) of the FeCoNi(CuAl)0.8Snx (0 ≤ x ≤ 0.10) HEAs increase greatly while the remanence (Br) decreases after the addition of Sn into FeCoNi(CuAl)0.8 HEA. The thermomagnetic curves indicate that the phases of the FeCoNi(CuAl)0.8Snx (0 ≤ x ≤ 0.10) HEAs will transform from FCC with low Tc to BCC phase with high Tc at temperature of 600–700 K. This work provides a new idea for FeCoNi(CuAl)0.8Snx (0 ≤ x ≤ 0.10) HEAs for their potential application as soft magnets to be used at high temperatures.

scholarly journals Microstructures and Mechanical Properties of As Cast (Al7.5Co21.9Cr10.9Ti5.0Fe21.9Ni32.8)100-xCux High-Entropy Alloys

2021 ◽  
Vol 8 ◽  
Author(s):  
Jiajun Li ◽  
Yu Dong ◽  
Zemin Wang ◽  
Min Liu ◽  
Yi Ding ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Atom Probe ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Cu Content ◽  
Transmission Electron ◽  
Microstructures And Mechanical Properties ◽  
Fcc Phase ◽  
Xrd Patterns

This study focused on the role of Cu in the microstructure characteristics and tensile properties of novel L12-strengthened multicomponent high-entropy alloys (HEAs). A series of as-cast (Al7.5Co21.9Cr10.9Ti5.0Fe21.9Ni32.8)100-xCux (x = 0.5, 2.5, 5.0) high-entropy alloys (HEAs) were prepared. The microstructures and mechanical properties of HEAs were investigated using X-ray diffraction, a scanning electron microscope, a transmission electron microscope, and atom probe tomography. The XRD patterns of HEAs confirmed that all HEAs consisted of the FCC phase and the L12 phase. As Cu content increased, the dendritic was gradually coarsened. The spherical L12 size decreased, and number density increased in the interdendritic regions (ID). The L12 mainly contained Ni, Ti, Al, and Cu. The acicular L12 size increased and was continuously distributed in the dendritic regions (DR) as the Cu content increased gradually. The ultimate strength and elongation decreased from 1,002 MPa, 20.0% to 906 MPa, 13.1%, respectively. The segregation rates of Ti, Cu, and Al increased in the DR and ID. The L12 nano-precipitates in the DR become denser and finer, while the L12 islets in the ID region increase and elongate. Large lattice distortion caused by Cu addition weakens the strength of the L12-FCC phase boundary, leading to the premature fracture of the three HEAs, which were the main reasons for the decreases in strength and ductility as Cu content increased.

scholarly journals Microstructure and Room Temperature Mechanical Properties of Different 3 and 4 Element Medium Entropy Alloys from HfNbTaTiZr System

Entropy ◽  
2019 ◽  
Vol 21 (2) ◽  
pp. 114 ◽  
Author(s):  
Jiří Zýka ◽  
Jaroslav Málek ◽  
Jaroslav Veselý ◽  
František Lukáč ◽  
Jakub Čížek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Testing ◽  
Room Temperature ◽  
High Entropy Alloys ◽  
Lower Strength ◽  
X Ray ◽  
High Entropy ◽  
Elongation To Failure ◽  
Zero Values ◽  
Bcc Phase

Refractory high entropy alloys (HEA) are promising materials for high temperature applications. This work presents investigations of the room temperature tensile mechanical properties of selected 3 and 4 elements medium entropy alloys (MEA) derived from the HfNbTaTiZr system. Tensile testing was combined with fractographic and microstructure analysis, using scanning electron microscope (SEM), wavelength dispersive spectroscope (WDS) and X-Ray powder diffraction (XRD). The 5 element HEA alloy HfNbTaTiZr exhibits the best combination of strength and elongation while 4 and 3 element MEAs have lower strength. Some of them are ductile, some of them brittle, depending on microstructure. Simultaneous presence of Ta and Zr in the alloy resulted in a significant reduction of ductility caused by reduction of the BCC phase content. Precipitation of Ta rich particles on grain boundaries reduces further the maximum elongation to failure down to zero values.

scholarly journals Effect of Atomic Size Difference on the Microstructure and Mechanical Properties of High-Entropy Alloys

Entropy ◽  
2018 ◽  
Vol 20 (12) ◽  
pp. 967 ◽  
Author(s):  
Chan-Sheng Wu ◽  
Ping-Hsiu Tsai ◽  
Chia-Ming Kuo ◽  
Che-Wei Tsai
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Grain Growth ◽  
Size Difference ◽  
High Entropy Alloys ◽  
Atomic Size ◽  
High Entropy ◽  
Microstructure And Mechanical Properties ◽  
Atomic Size Difference ◽  
Fcc Phase

The effects of atomic size difference on the microstructure and mechanical properties of single face-centered cubic (FCC) phase high-entropy alloys are studied. Single FCC phase high-entropy alloys, namely, CoCrFeMnNi, Al0.2CoCrFeMnNi, and Al0.3CoCrCu0.3FeNi, display good workability. The recrystallization and grain growth rates are compared during annealing. Adding Al with 0.2 molar ratio into CoCrFeMnNi retains the single FCC phase. Its atomic size difference increases from 1.18% to 2.77%, and the activation energy of grain growth becomes larger than that of CoCrFeMnNi. The as-homogenized state of Al0.3CoCrCu0.3FeNi high-entropy alloy becomes a single FCC structure. Its atomic size difference is 3.65%, and the grain growth activation energy is the largest among these three kinds of single-phase high-entropy alloys. At ambient temperature, the mechanical properties of Al0.3CoCrCu0.3FeNi are better than those of CoCrFeMnNi because of high lattice distortion and high solid solution hardening.

scholarly journals Effects of Al Addition on Microstructures and Mechanical Properties of CoCrFeMnNiAlx High Entropy Alloy Films

Entropy ◽  
2019 ◽  
Vol 22 (1) ◽  
pp. 2 ◽  
Author(s):  
Ya-Chu Hsu ◽  
Chia-Lin Li ◽  
Chun-Hway Hsueh
Keyword(s):  
Mechanical Properties ◽  
Compressive Yield Strength ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
Alloy Films ◽  
High Entropy ◽  
Al Content ◽  
Microstructures And Mechanical Properties ◽  
Fcc Phase ◽  
Bcc Phase

CoCrFeMnNiAlx (x = 0, 0.07, 0.3, 0.6, 1.0, 1.3) high-entropy alloy films (HEAFs) were processed by co-sputtering of CoCrFeMnNi alloy and Al targets. The effects of Al content on the microstructures and mechanical properties of HEAFs were studied. The XRD results indicated that the crystalline structure changed from the single face-centered cubic (FCC) phase for x = 0 and 0.07 to duplex FCC + body-centered cubic (BCC) phases for x = 0.3 and 0.6, and eventually, to a single BCC phase for x = 1.0 and 1.3, which agreed with the corresponding selected-area electron diffraction patterns. Also, nanotwins were observed in the FCC phase. Mechanical properties of films were studied using nanoindentation and micropillar compression tests. The hardness increased from 5.71 GPa at x = 0 to 8.74 GPa at x = 1.3. The compressive yield strength increased from 1.59 GPa to 3.73 GPa; however, the fracture strain decreased from 20.91% (no fracture) to 13.78% with the increasing Al content. Both nanotwins and BCC phase contributed to the strengthening effects for CoCrFeMnNiAlx HEAFs. Also, compared to the bulk CoCrFeMnNiAlx counterpart, the film exhibited much higher hardness and strength because of the much smaller grain size and the presence of nanotwins.

Temperature Dependent Yield Strength, Strain Hardening and Failure of the CoCrFeNiMnVx High Entropy Alloys

2017 ◽  
Vol 891 ◽  
pp. 438-443
Author(s):  
Aleksey V. Podolskiy ◽  
Elena D. Tabachnikova ◽  
Marina O. Laktionova ◽  
Natalia A. Bereznaia ◽  
Mikhail A. Tikhonovsky ◽  
...  
Keyword(s):  
Yield Strength ◽  
Strain Hardening ◽  
High Entropy Alloys ◽  
Temperature Dependent ◽  
Σ Phase ◽  
High Entropy ◽  
Temperature Dependences ◽  
Fcc Phase ◽  
Different Content ◽  
Main Deformation

Several structural states of the CoCrFeNiMnVx (x=0, 0.25, 0.5, 0.75) high entropy alloys with different content of the intermetallic σ phase are studied in uniaxial compression in temperature range 4.2-300 K. Peculiarities of strain hardening stages and temperature dependences of the yield strength are registered and analyzed considering dislocation sliding as main deformation mechanism in matrix fcc phase. Influence of σ phase particles, deformation twins and stacking faults on the deformation behavior of the CoCrFeNiMnVx alloy is discussed.

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