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 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 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.

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.

Microstructures and Wear Resistance of Al1.5CrFeNiTi0.5 and Al1.5CrFeNiTi0.5W0.5 High Entropy Alloy Coatings Manufactured by Laser Cladding

2019 ◽  
Vol 956 ◽  
pp. 154-159 ◽  
Author(s):  
Hui Liang ◽  
Bing Yang Gao ◽  
Ya Ning Li ◽  
Qiu Xin Nie ◽  
Zhi Qiang Cao
Keyword(s):  
Wear Resistance ◽  
Laser Cladding ◽  
Dendritic Structure ◽  
Laves Phase ◽  
High Entropy Alloy ◽  
Second Phase ◽  
Laves Phases ◽  
High Entropy ◽  
Two Phases ◽  
Bcc Phase

For the purpose of expanding the application scope of HEA coating manufactured on the surface modification of materials, in this work, the Al1.5CrFeNiTi0.5 and Al1.5CrFeNiTi0.5W0.5 HEA coatings were successfully manufactured using laser cladding method on SUS304. The microstructures and wear resistance of coatings are researched systematically. It is found that the W0 and W0.5 HEA coatings all exhibit the dendritic structure, which are constituted by BCC phases and Laves phases. With W element addition, the phase structures of W0.5 coating remain unchanged. W is dissolved in both two phases, but the solid solubility in Laves phase is higher compared to that in BCC phase. W0.5 coating with the highest microhardness of 848.34 HV, and the W0 coating with the microhardness of 811.45 HV, both of whose microhardness are four times more than that of SUS304 substrate. Among all samples, the W0.5 coating shows the optimal wear performance because of its larger content of hard second phase ( Laves phase).

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.

Microstructure and Mechanical Properties of a New Refractory HfNbSi0.5TiVZr High Entropy Alloy

2016 ◽  
Vol 849 ◽  
pp. 76-84 ◽  
Author(s):  
Yan Zhang ◽  
Yuan Liu ◽  
Yan Xiang Li ◽  
Xiang Chen ◽  
Hua Wei Zhang
Keyword(s):  
Room Temperature ◽  
Solid Phase ◽  
Cast Alloy ◽  
Intermetallic Phase ◽  
Dendritic Structure ◽  
Formation Enthalpy ◽  
Compressive Yield Strength ◽  
High Entropy Alloy ◽  
High Entropy ◽  
New Phase

A new refractory alloy HfNbSi0.5TiVZr was synthesized by induction levitation melting with the aim to achieve an excellent strength and toughness balance of the Hf-Nb-Ti-Zr based alloy. The as-cast alloy with density of ρ=7.75g/cm3 and microhardness of Hv=464 had the microstructure consisting of bcc solid solution with little vanadium rich phase and fine intermetallic phase presented dendritic structure. Mixing entropy and formation enthalpy can explain this behavior. After heat treatment at 1373K for 4 h, no new phase come into being but elements solute more fully. Compressive yield strength of the alloy gradually decreased from 1540MPa at room temperature to 371MPa at 1073K in as-cast state and decreased from 1483MPa at room temperature to 102MPa at 1073K after annealed. Comparing with the similar high entropy alloys, the structure combining silicide and continuous solid phase have a great benefit to the balance of strength and ductility.

scholarly journals Effect of Al Content on Phase Compositions of FeNiCoCrMo0.5Alx High Entropy Alloy

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1734
Author(s):  
Anton Semikolenov ◽  
Svetlana Shalnova ◽  
Victor Klinkov ◽  
Valentina Andreeva ◽  
Maria Salynova ◽  
...  
Keyword(s):  
Solid Solution ◽  
Phase Formation ◽  
Test Methods ◽  
Point Of View ◽  
High Entropy Alloy ◽  
Induction Melting ◽  
Σ Phase ◽  
High Entropy ◽  
Al Content ◽  
B2 Phase

The FeCoNiCrMo0.5Alx system with x up to 2.13 was analyzed from the point of view of evolution of the phase composition and microstructure. Cast samples were synthesized by induction melting and analyzed by X-ray diffraction, energy dispersive spectroscopy, scanning electron microscopy, and Vickers microhardness test methods. Phase compositions of these alloys in dependance on Al concentration consist of FCC solid solution, σ-phase, NiAl-based B2 phase, and BCC solid solution enriched with Mo and Cr. Phase formation principles were studied. Al dissolves in a FeCoNiCrMo0.5 FCC solid solution up to 8 at.%.; at higher concentrations, Al attracts Ni, removing it from FCC solid solution and forming the B2 phase. Despite Al not participating in σ-phase formation, an increase in Al concentration to about 20 at.% leads to a growth in the σ-phase fraction. The increase in the σ-phase was caused by an increase in the amount of B2 because the solubility of σ-forming Mo and Cr in B2 was less than that in the FCC solution. A further increase in Al concentration led to an excess of Mo and Cr in the solution, which formed a disordered BCC solid solution. The hardness of the alloys attained the maximum of 630 HV at 22 and 32 at.% Al.

Microstructural Evolution and Mechanical Properties in a Mn1.05Fe1.05CoNiCu0.9 High Entropy Alloy

2017 ◽  
Vol 737 ◽  
pp. 44-49 ◽  
Author(s):  
Seung Min Oh ◽  
Sun Ig Hong
Keyword(s):  
Mechanical Properties ◽  
Single Phase ◽  
Cast Alloy ◽  
High Entropy Alloy ◽  
Microstructural Stability ◽  
Dendrite Structure ◽  
High Entropy ◽  
Melting Temperatures ◽  
The Matrix ◽  
Fcc Structure

In the present study, the microstructural stability and mechanical properties of a MnFeCoNiCu alloy in which Cr was replaced by Cu from Cantor composition (CoCrFeMnNi) was studied. In the as-cast alloy, the dendrite arms are enriched with Cu and Mn and matrix between dendrite arms is enriched with Fe and Co. Ni was richer in the matrix, but also observed in the dendrite arms. Cu and Mn tend to segregate and solidify initially because the melting temperatures of Cu and Mn are lower than Fe and Co, resulting in the growth of Cu-Mn dendrite. After homogenization, the dendrites structure disappeared and grain boundaries are visible, indicating the segregated elements in the dendrite structure were homogenized. The presence of single phase FCC structure was confirmed after homogenization. The tensile strength of 1220 MPa with the ductility of 6 % was obtained in MnFeCoNiCu alloy.

scholarly journals Effect of Zr Addition on the Microstructure and Mechanical Properties of CoCrFeNiMn High-Entropy Alloy Synthesized by Spark Plasma Sintering

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 810 ◽  
Author(s):  
Hongling Zhang ◽  
Lei Zhang ◽  
Xinyu Liu ◽  
Qiang Chen ◽  
Yi Xu
Keyword(s):  
Spark Plasma Sintering ◽  
Raw Materials ◽  
Alloy System ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
Σ Phase ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Fcc Phase

As a classic high-entropy alloy system, CoCrFeNiMn is widely investigated. In the present work, we used ZrH2 powders and atomized CoCrFeNiMn powders as raw materials to prepare CoCrFeNiMnZrx (x = 0, 0.2, 0.5, 0.8, 1.0) alloys by mechanical alloying (MA), followed by spark plasma sintering (SPS). During the MA process, a small amount of Zr (x ≤ 0.5) can be completely dissolved into CoCrFeNiMn matrix, when the Zr content is above 0.5, the ZrH2 is excessive. After SPS, CoCrFeNiMn alloy is still as single face-centered cubic (FCC) solid solution, and CoCrFeNiMnZrx (x ≥ 0.2) alloys have two distinct microstructural domains, one is a single FCC phase without Zr, the other is a Zr-rich microstructure composed of FCC phase, B2 phase, Zr2Ni7, and σ phase. The multi-phase microstructures can be attributed to the large lattice strain and negative enthalpy of mixing, caused by the addition of Zr. It is worth noting that two types of nanoprecipitates (body-centered cubic (BCC) phase and Zr2Ni7) are precipitated in the Zr-rich region. These can significantly increase the yield strength of the alloys.

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.

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