scholarly journals A NOVEL 3d TRANSITION-METAL ALCOCRCUTI HIGH-ENTROPY ALLOY

2021 ◽  
Vol 55 (3) ◽  
Author(s):  
Menglan Shen ◽  
Yuanming Huo ◽  
Tao He ◽  
Yong Xue ◽  
Yujia Hu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Ultimate Strength ◽  
Cast Alloy ◽  
Eutectic Structure ◽  
Primary Phase ◽  
High Entropy Alloy ◽  
Compressive Properties ◽  
High Entropy ◽  
Mechanics Performance ◽  
Interdendritic Phase

The phase component, microstructure and compressive properties of a novel 3d transition metal high entropy alloy, AlCoCrCuTi, in as-cast and annealed conditions were investigated. The phases of the as-cast AlCoCrCuTi alloy are composed of primary phase AlCo2Ti (L21), eutectic structure {AlCo2Ti (L21)+ Al3Cr7 (BCC)} and interdendritic phase AlCu2Ti (L21). Through annealing, a rosette feature of the as-cast AlCo2Ti + Al3Cr7 eutectic structure is deteriorated due to the lath-like Al3Cr7 changed to finely-divided one. In mechanics performance, the as-cast alloy exhibits a balanced synergy in hardness (593±37 HV) and ultimate strength (745 MPa), while the hardness of the annealed alloy slightly increases to 647±23 HV at the expense of the ultimate strength. Moreover, the alloy either in as-cast or annealed conditions unfortunately display a typically brittle character. The deficiency of elongation might stem from the diversified brittle and hard phases incorporated, such as AlCo2Ti + Al3Cr7.

scholarly journals Superconductivity in CuAl2-type Co0.2Ni0.1Cu0.1Rh0.3Ir0.3Zr2 with a high-entropy-alloy transition metal site

2020 ◽  
Vol 9 (3) ◽  
pp. 141-147
Author(s):  
Yoshikazu Mizuguchi ◽  
Md. Riad Kasem ◽  
Tatsuma D. Matsuda
Keyword(s):  
Transition Metal ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Metal Site

scholarly journals Cr-Mo-V-W: A new refractory and transition metal high-entropy alloy system

2019 ◽  
Vol 158 ◽  
pp. 141-145 ◽  
Author(s):  
D. Ikeuchi ◽  
D.J.M. King ◽  
K.J. Laws ◽  
A.J. Knowles ◽  
R.D. Aughterson ◽  
...  
Keyword(s):  
Transition Metal ◽  
Alloy System ◽  
High Entropy Alloy ◽  
High Entropy

Dendritic Growth of Rapid-Solidified Eutectic High-Entropy Alloy

2021 ◽  
Vol 1035 ◽  
pp. 46-50
Author(s):  
Lei Gang Cao ◽  
Peng Yu Hou ◽  
Ahmed Nassar ◽  
Andrew M. Mullis
Keyword(s):  
Cooling Rate ◽  
Single Phase ◽  
Eutectic Growth ◽  
Sample Surface ◽  
Eutectic Structure ◽  
High Entropy Alloy ◽  
Drop Tube ◽  
Dendrite Morphology ◽  
High Entropy ◽  
Mould Casting

Mould casting and drop-tube techniques were used to solidify a AlCoCrFeNi2.1 eutectic high-entropy alloy under conditions of high cooling rate. The samples obtained from two different methods present the same phase constituent, FCC and B2 phases. During mould casting experiments the alloy almost solidified into the eutectic structure consisting of lamellar and anomalous morphology, with a tiny fraction of cellular and dendrite morphology being observed at certain sites of the sample surface due to the corresponding high cooling rate. Instead, during drop-tube experiments a typical, coarse dendrite structure of FCC single phase was formed across the entire 106-150 μm particle. The cellular structure can also be formed directly from the melt. The rest region solidified into the general eutectic morphology as was observed in the casting rods. The results clearly indicate the transition from coupled eutectic growth to single-phase dendrite growth with increasing departures from equilibrium for the multi-component AlCoCrFeNi2.1 eutectic high-entropy alloy.

scholarly journals Thermoelectric Properties of CoCrFeNiNbx Eutectic High Entropy Alloys

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 762
Author(s):  
Kaiming Han ◽  
Hui Jiang ◽  
Tiandang Huang ◽  
Mingyu Wei
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Thermoelectric Properties ◽  
Phase Interface ◽  
Lamellar Microstructure ◽  
Eutectic Structure ◽  
Great Promise ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Nb Content

Bulk CoCrFeNiNb0.45 eutectic high entropy alloy (EHEA) with ultrafine-lamellar microstructure shows outstanding thermal stability. The EHEA offers opportunities for the development of thermoelectric materials. In this paper, the thermoelectric properties of a CoCrFeNiNbx (x = 0, 0.25, and 0.45) EHEA system were investigated. The results indicated that the electrical conductivity decreased with a rise in Nb content in the CoCrFeNiNbx alloys, which resulted from the increased eutectic structure and phase interface. Moreover, the thermal conductivity increased with increased Nb content at low temperature (T ≤ 473 K), while thermal conductivity decreased at high temperature (T > 573 K). The CoCrFeNiNb0.45 full eutectic high entropy alloy exhibited the lowest thermal conductivity and higher thermoelectric figure of merit (ZT) at a high temperature (T > 573 K), which shows great promise for the thermoelectric application at high temperature.

Microstructure and Mechanical Properties of Equitomic CoCrFeCuNi High Entropy Alloy

2018 ◽  
Vol 765 ◽  
pp. 149-154 ◽  
Author(s):  
Seung Min Oh ◽  
Sun Ig Hong
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Cold Rolling ◽  
Cast Alloy ◽  
Cold Work ◽  
High Entropy Alloy ◽  
Second Phase ◽  
Rich Phase ◽  
High Entropy ◽  
Microstructure And Mechanical Properties

Microstructure and mechanical properties of cast and cold-rolled equitomic CoCrFeCuNi alloy in which Mn was substituted by Cu from Cantor alloy was studied. The separation into two solid solutions (Cr-Co-Fe rich and Cu-rich phases) were observed in CoCrFeCuNi. Coarsening and widening of interdendritic Cu-rich phase after homogenization was observed after homogenization, suggesting Cu-rich phase is thermodynamically stable. The compressive stress-strain curves of homogenized cast CoCrFeCuNi alloy exhibited the reasonably high strength and excellent deformability for the cast alloy. The yield strength increased up to 960MPa after cold rolling from 265MPa of the homogenized cast alloy. The significant increase of yield strength is thought to be associated with the alignment of Cu-rich second phase in addition to cold work dislocation storage after cold rolling.

scholarly journals A Novel Al0.5CuFeNiV High Entropy Alloy: Phase Analysis, Microstructure and Compressive Properties

2021 ◽  
Vol 62 (5) ◽  
pp. 620-624
Author(s):  
Jiaojiao Yi ◽  
Lu Wang ◽  
Fuyang Cao ◽  
Lin Yang ◽  
Mingqin Xu
Keyword(s):  
Phase Analysis ◽  
High Entropy Alloy ◽  
Compressive Properties ◽  
High Entropy

scholarly journals Spinodal Decomposition and Mechanical Response of a TiZrNbTa High-Entropy Alloy

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3508 ◽  
Author(s):  
Liu ◽  
Huang ◽  
Chuang ◽  
Chou ◽  
Wei ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Spinodal Decomposition ◽  
Mechanical Response ◽  
Cast Alloy ◽  
High Entropy Alloy ◽  
Body Centered Cubic ◽  
High Entropy ◽  
Bcc Structure ◽  
20 Nm ◽  
Interconnected Structure

In this study, the effects of spinodal decomposition on the microstructures and mechanical properties of a TiZrNbTa alloy are investigated. The as-cast TiZrNbTa alloy possesses dual phases of TiZr-rich inter-dendrite (ID) and NbTa-rich dendrite (DR) domains, both of which have a body-centered cubic (BCC) structure. In the DRs of the as-cast alloy, the α and ω precipitates are found to be uniformly distributed. After homogenization at 1100 °C for 24 h followed by water quenching, spinodal decomposition occurs and an interconnected structure with a wavelength of 20 nm is formed. The α and ω precipitates remained in the structure. Such a fine spinodal structure strengthens the alloy effectively. Detailed strengthening calculations were conducted in order to estimate the strengthening contributions from the α and ω precipitates, as well as the spinodal decomposition microstructure.

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 On The Microstructures and Hardness of The Nb-24Ti-18Si-5Al-5Cr-5Ge and Nb-24Ti-18Si-5Al-5Cr-5Ge-5Hf (at.%) Silicide Based Alloys

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2655 ◽  
Author(s):  
Zifu Li ◽  
Panos Tsakiropoulos
Keyword(s):  
Cast Alloy ◽  
Lattice Parameter ◽  
Primary Phase ◽  
Laves Phase ◽  
Valence Electron Concentration ◽  
Atomic Size ◽  
High Entropy ◽  
Alloying Additions ◽  
Heat Treated ◽  
Alloy Hardness

The microstructures and hardness of the as cast and heat treated (1400 °C/100 h) alloys Nb-24Ti-18Si-5Ge-5Cr-5Al (ZF6) and Nb-24Ti-18Si-5Ge-5Cr-5Al-5Hf (ZF9) were studied. Both alloys were compared with refractory metal bcc solid solution + intermetallic High Entropy Alloys (HEAs). There was macrosegregation of Si, Ti, Cr and Al in both alloys. The roles of Ge and Hf on macrosegregation are discussed. In both alloys the primary phase was the βNb5Si3. In the as cast alloy ZF6 the Nbss, βNb5Si3 and C14-NbCr2 Laves phase and Nbss + βNb5Si3 eutectic were formed. The microstructure of the as cast alloy ZF9 consisted of Nbss, βNb5Si3, γNb5Si3 and C14-NbCr2 Laves phase. The heat-treated microstructures of the alloys ZF6 and ZF9 consisted of Nbss, βNb5Si3 and αNb5Si3 and Nbss, βNb5Si3, αNb5Si3 and γNb5Si3, respectively. The surfaces of both alloys were contaminated by oxygen where TiO2 and HfO2 formed respectively in the alloys ZF6 and ZF9. Alloying with Hf increased the lattice parameter of Nbss and decreased the hardness of ZF9 and Nb5Si3. The roles of alloying additions on the hardness of the Nbss and Nb5Si3 and relationships between alloy hardness and alloy parameters VEC (valence electron concentration), δ (related to atomic size) and Δχ (related to electronegativity) were discussed.

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