Microstructures and Phase Formation of Refractory MoNbTaVZr High Entropy Alloy

2020 ◽  
Vol 993 ◽  
pp. 384-390
Author(s):  
Hao Yu Wang ◽  
Zi Yue Wang ◽  
Zhi Sheng Nong ◽  
Ji Jie Wang ◽  
Tian Nan Man ◽  
...  
Keyword(s):  
Cast Alloy ◽  
Testing Machine ◽  
High Entropy Alloy ◽  
Chemical Compositions ◽  
X Ray ◽  
Component Distribution ◽  
High Entropy ◽  
Unknown Phase ◽  
Universal Testing ◽  
Second Phases

Microstructures, component distribution and mechanical properties of a refractory high entropy alloy MoNbTaVZr were investigated by scanning electron microscope, X-ray diffractometer and universal testing machine, and the formation rule of second phases in as-cast alloy was discussed by the results of first principle calculations. The results show that as-cast MoNbTaVZr alloy is composed of two solid solutions with body centered cubic structure, together with Mo2Zr and an unknown phase. The chemical compositions of dendritic regions are relatively uniform, while Zr and V elements are rich in interdendritic regions. There is a short yielding phase when as-cast alloy was operated by the compression. According to calculations, the C15 Mo2Zr Laves phase with the strongest formation ability and highest structural stability would be formed preferentially in MoNbTaVZr refractory high entropy alloy.

scholarly journals A Study of Thin Film Resistors Prepared Using Ni-Cr-Si-Al-Ta High Entropy Alloy

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Ruei-Cheng Lin ◽  
Tai-Kuang Lee ◽  
Der-Ho Wu ◽  
Ying-Chieh Lee
Keyword(s):  
Annealing Temperature ◽  
Phase Evolution ◽  
Amorphous Structure ◽  
High Entropy Alloy ◽  
X Ray Diffraction ◽  
Temperature Coefficient Of Resistance ◽  
X Ray ◽  
High Entropy ◽  
Transmission Electron ◽  
Thin Film Resistors

Ni-Cr-Si-Al-Ta resistive thin films were prepared on glass and Al2O3substrates by DC magnetron cosputtering from targets of Ni0.35-Cr0.25-Si0.2-Al0.2casting alloy and Ta metal. Electrical properties and microstructures of Ni-Cr-Si-Al-Ta films under different sputtering powers and annealing temperatures were investigated. The phase evolution, microstructure, and composition of Ni-Cr-Si-Al-Ta films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Auger electron spectroscopy (AES). When the annealing temperature was set to 300°C, the Ni-Cr-Si-Al-Ta films with an amorphous structure were observed. When the annealing temperature was at 500°C, the Ni-Cr-Si-Al-Ta films crystallized into Al0.9Ni4.22, Cr2Ta, and Ta5Si3phases. The Ni-Cr-Si-Al-Ta films deposited at 100 W and annealed at 300°C which exhibited the higher resistivity 2215 μΩ-cm with −10 ppm/°C of temperature coefficient of resistance (TCR).

scholarly journals Element Effects on High-Entropy Alloy Vacancy and Heterogeneous Lattice Distortion Subjected to Quasi-equilibrium Heating

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
E-Wen Huang ◽  
Hung-Sheng Chou ◽  
K. N. Tu ◽  
Wei-Song Hung ◽  
Tu-Ngoc Lam ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Lattice Structure ◽  
High Entropy Alloy ◽  
Quasi Equilibrium ◽  
X Ray ◽  
Structure Relaxation ◽  
High Entropy ◽  
Spatially Resolved ◽  
Formation Enthalpies ◽  
Different Characteristics

Abstract We applied Simmons–Balluffi methods, positron measurements, and neutron diffraction to estimate the vacancy of CoCrFeNi and CoCrFeMnNi high-entropy alloys (HEAs) using Cu as a benchmark. The corresponding formation enthalpies and associated entropies of the HEAs and Cu were calculated. The vacancy-dependent effective free volumes in both CoCrFeNi and CoCrFeMnNi alloys are greater than those in Cu, implying the easier formation of vacancies by lattice structure relaxation of HEAs at elevated temperatures. Spatially resolved synchrotron X-ray measurements revealed different characteristics of CoCrFeNi and CoCrFeMnNi HEAs subjected to quasi-equilibrium conditions at high temperatures. Element-dependent behavior revealed by X-ray fluorescence (XRF) mapping indicates the effect of Mn on the Cantor Alloy.

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.

Study to Microstructure and Mechanical Properties of Mg Containing High Entropy Alloys

2010 ◽  
Vol 650 ◽  
pp. 265-271 ◽  
Author(s):  
Rui Li ◽  
Jia Cheng Gao ◽  
Ke Fan
Keyword(s):  
Mechanical Properties ◽  
Testing Machine ◽  
High Hardness ◽  
Material Strength ◽  
High Entropy Alloy ◽  
Icosahedral Quasicrystal ◽  
Induction Melting ◽  
High Entropy ◽  
Microstructure And Mechanical Properties ◽  
Thermal Analyzer

In this paper, alloys with compositions of Mgx(MnAlZnCu)100-x (x: atomic percentage; x=20, 33, 43, 45.6 and 50 respectively) were designed by using the strategy of equiatomic ratio and high entropy of mixing. Microstructure and mechanical properties of the new high entropy alloy were studied. The alloys were prepared by induction melting and then were cast in a copper mold in air. The alloy samples were examined by microhardness tester, XRD, SEM, thermal analyzer and testing machine for material strength. Alloys were composed mainly of h.c.p phase and Al-Mn icosahedral quasicrystal phases. The alloys exhibited moderate densities which were from 4.29g•cm-3 to 2.20g•cm-3, high hardness (429HV-178HV) and high compression strength (500MPa-400MPa) at room temperature. The extensibility was increased with Mg from 20at% (atomic percentage) to 50at%.

scholarly journals Strength enhancement of concrete using incinerated agricultural waste as supplementary cement materials

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Teh Sabariah Binti Abd Manan ◽  
Nur Liyana Mohd Kamal ◽  
Salmia Beddu ◽  
Taimur Khan ◽  
Daud Mohamad ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Agricultural Waste ◽  
Testing Machine ◽  
Strength Properties ◽  
Engineering Properties ◽  
Hydration Reaction ◽  
X Ray ◽  
Transition Zones ◽  
Strength Enhancement ◽  
Universal Testing

AbstractThe potassium (K) and sodium (Na) elements in banana are needed for hydration reaction that can enhance the strength properties of concrete. This research aims (a) to determine the material engineering properties of banana skin ash (BSA) and concrete containing BSA, (b) to measure the strength enhancement of concrete due to BSA, and (c) to identify optimal application of BSA as supplementary cement materials (SCM) in concrete. The BSA characterization were assessed through X-ray fluorescence (XRF) and Blaine’s air permeability. The workability, compressive strength, and microstructures of concrete containing BSA were analysed using slump test, universal testing machine (UTM) and scanning electron microscope (SEM). A total of 15 oxides and 19 non-oxides elements were identified in BSA with K (43.1%) the highest and Na was not detected. At 20 g of mass, the BSA had a higher bulk density (198.43 ± 0.00 cm3) than ordinary Portland cement (OPC) (36.32 ± 0.00 cm3) indicating availability of large surface area for water absorption. The concrete workability was reduced with the presence of BSA (0% BSA: > 100 mm, 1% BSA: 19 ± 1.0 mm, 2%: 15 ± 0.0 mm, 3% BSA: 10 ± 0.0 mm). The compressive strength increased with the number of curing days. The concrete microstructures were improved; interfacial transition zones (ITZ) decreased with an increase of BSA. The optimal percentage of BSA obtained was at 1.25%. The established model showed significant model terms (Sum of Squares = 260.60, F value = 69.84) with probability of 0.01% for the F-value to occur due to noise. The established model is useful for application in construction industries.

scholarly journals Preparation of Bulk TiZrNbMoV and NbTiAlTaV High-Entropy Alloys by Powder Sintering

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1748
Author(s):  
Yaqi Wu ◽  
Peter K. Liaw ◽  
Yong Zhang
Keyword(s):  
Raw Materials ◽  
Testing Machine ◽  
Compression Rate ◽  
High Entropy Alloys ◽  
Alloy Structure ◽  
Metal Compounds ◽  
High Entropy ◽  
Universal Testing ◽  
Powder Sintering ◽  
Scanning Electron

The refractory HEAs block material was prepared by powder sintering, using an equal atomic proportion of mixed TiZrNbMoV and NbTiAlTaV metal powder raw materials. The phase was analyzed, using an XRD. The microstructure of the specimen was observed, employing a scanning electron microscope, and the compressive strength of the specimen was measured, using an electronic universal testing machine. The results showed that the bulk cubic alloy structure was obtained by sintering at 1300 °C and 30 MPa for 4 h, and a small amount of complex metal compounds were contained. According to the pore distribution, the formed microstructure can be divided into dense and porous zones. At a compression rate of 10−4s−1, the yield strengths of TiZrNbMoV and NbTiAlTaV alloys are 1201 and 700 MPa, respectively.

scholarly journals Microstructure Evolution of FeNiCoCrAl1.3Mo0.5 High Entropy Alloy during Powder Preparation, Laser Powder Bed Fusion, and Microplasma Spraying

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7870
Author(s):  
Anton Semikolenov ◽  
Pavel Kuznetsov ◽  
Tatyana Bobkova ◽  
Svetlana Shalnova ◽  
Olga Klimova-Korsmik ◽  
...  
Keyword(s):  
Solid Solution ◽  
Phase Composition ◽  
Cast Alloy ◽  
High Entropy Alloy ◽  
Gas Atomization ◽  
Face Centered Cubic ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
X Ray

In the present study, powder of FeCoCrNiMo0.5Al1.3 HEA was manufactured by gas atomization process, and then used for laser powder bed fusion (L-PBF) and microplasma spraying (MPS) technologies. The processes of phase composition and microstructure transformation during above mentioned processes and subsequent heat treatment were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and differential thermal analysis (DTA) methods. It was found that gas atomization leads to a formation of dendrites of body centered cubic (BCC) supersaturated solid solution with insignificant Mo-rich segregations on the peripheries of the dendrites. Annealing leads to an increase of element segregations till to decomposition of the BCC solid solution and formation of σ-phase and B2 phase. Microstructure and phase composition of L-PBF sample are very similar to those of the powder. The MPS coating has a little fraction of face centered cubic (FCC) phase because of Al oxidation during spraying and formation of regions depleted in Al, in which FCC structure becomes more stable. Maximum hardness (950 HV) is achieved in the powder and L-PBF samples after annealing at 600 °C. Elastic modulus of the L-PBF sample, determined by nanoindentation, is 165 GPa, that is 12% lower than that of the cast alloy (186 GPa).

scholarly journals Effect of V and Ti on the Oxidation Resistance of WMoTaNb Refractory High-Entropy Alloy at High Temperatures

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 41
Author(s):  
Shuaidan Lu ◽  
Xiaoxiao Li ◽  
Xiaoyu Liang ◽  
Wei Yang ◽  
Jian Chen
Keyword(s):  
Oxidation Resistance ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Early Stage ◽  
Mass Gain ◽  
High Entropy Alloy ◽  
High Entropy Alloys ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Entropy

Alloying with V and Ti elements effectively improves the strength of WMoTaNb refractory high entropy alloys (RHEAs) at elevated temperatures. However, their effects on the oxidation resistance of WMoTaNb RHEAs are unknown, which is vitally important to their application at high temperatures. In this work, the effect of V and Ti on the oxidation behavior of WMoTaNb RHEA at 1000 °C was investigated using a thermogravimetric system, X-ray diffraction and scanning electron microscopy. The oxidation of all alloys was found to obey a power law passivating oxidation at the early stage. The addition of V aggravates the volatility of V2O5, MoO3 and WO3, and leads to disastrous internal oxidation. The addition of Ti reduces the mass gain in forming the full coverage of passivating scale and prolongs the passivation duration of alloys.

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