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.

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).

Microstructure and Mechanical Properties of VTaTiMoAlx Refractory High Entropy Alloys

2017 ◽  
Vol 898 ◽  
pp. 638-642 ◽  
Author(s):  
Dong Xu Qiao ◽  
Hui Jiang ◽  
Xiao Xue Chang ◽  
Yi Ping Lu ◽  
Ting Ju Li
Keyword(s):  
Mechanical Properties ◽  
Vacuum Arc ◽  
High Entropy Alloys ◽  
X Ray Diffraction ◽  
Dendrite Structure ◽  
X Ray ◽  
High Entropy ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Microstructure And Mechanical Properties

A series of refractory high-entropy alloys VTaTiMoAlx with x=0,0.2,0.6,1.0 were designed and produced by vacuum arc melting. The effect of added Al elements on the microstructure and mechanical properties of refractory high-entropy alloys were investigated. The X-ray diffraction results showed that all the high-entropy alloys consist of simple BCC solid solution. SEM indicated that the microstructure of VTaTiMoAlx changes from equiaxial dendritic-like structure to typical dendrite structure with the addition of Al element. The composition of different regions in the alloys are obtained by energy dispersive spectroscopy and shows that Ta, Mo elements are enriched in the dendrite areas, and Al, Ti, V are enriched in inter-dendrite areas. The yield strength and compress strain reach maximum (σ0.2=1221MPa, ε=9.91%) at x=0, and decrease with the addition of Al element at room temperature. Vickers hardness of the alloys improves as the Al addition.

Yttrium Implantation and Manganese Addition Element Effects on the High Temperature Oxidation Resistance of a Model Steel

2008 ◽  
Vol 595-598 ◽  
pp. 897-905
Author(s):  
Eric Caudron ◽  
Régis Cueff ◽  
Christophe Issartel ◽  
N. Karimi ◽  
Frédéric Riffard ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
High Temperatures ◽  
Mixed Oxides ◽  
Rutherford Backscattering Spectrometry ◽  
High Energy ◽  
X Ray Diffraction ◽  
Temperature Oxidation ◽  
X Ray ◽  
Steel Oxidation ◽  
Yttrium Implantation

Manganese addition and subsequent yttrium implantation effects on extra low carbon steel were studied by Rutherford Backscattering Spectrometry (RBS), Reflection High Energy Electron Diffraction (RHEED), X-ray Diffraction (XRD) and Glancing Angle X-ray Diffraction (GAXRD). Thermogravimetry and in situ X-Ray Diffraction at 700°C and PO2=0.04 Pa for 24h were used to determine the manganese alloying addition and subsequent yttrium implantation effects on reference steel oxidation resistance at high temperatures. This study clearly shows the combined effect of manganese alloying addition and subsequent yttrium implantation which promotes the formation of several yttrium mixed oxides seem to be responsible for the improved reference steel oxidation resistance at high temperatures.

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.

scholarly journals Crystalline Structures of Some High Entropy Alloys Obtained by Neutron and X-Ray Diffraction

2015 ◽  
Vol 128 (4) ◽  
pp. 552-557 ◽  
Author(s):  
U. Dahlborg ◽  
J. Cornide ◽  
M. Calvo-Dahlborg ◽  
T.C. Hansen ◽  
Z. Leong ◽  
...  
Keyword(s):  
High Entropy Alloys ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystalline Structures ◽  
High Entropy

Interfacial Reaction of CoCrFeNi High Entropy Alloy in Molten Al

2019 ◽  
Vol 944 ◽  
pp. 176-181
Author(s):  
Yao Hu ◽  
Jun Tao He ◽  
Yu Cai Wu ◽  
Yong Dong ◽  
Zheng Rong Zhang
Keyword(s):  
Solid Solution ◽  
High Entropy Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Entropy ◽  
Solid Solution Layer ◽  
Bcc Structure ◽  
Solution Layer ◽  
Al Matrix ◽  
Dipping Time

In this paper, we studied the element diffusion behaviors of the multi-principal CoCrFeNi high entropy alloy in molten Al at 700°C. Microstructure, structure and microhardness in the diffusion interfaces of CoCrFeNi and Al are studied by the X-ray diffraction, the scanning electron microscopy, the energy spectrometry, and the microhardness tester. The results showed that a complex chemical reaction occurred at the interface between the high-entropy alloy and the Al. A mixture of FCC + BCC solid solution layer was first formed. Then a bulk Al13Cr2 compound formed near the Al of the solid solution layer. With the increase of dipping time, the thickness of the solid solution layer remained unchanged, and the compounds gradually changed into spheres distributed in the Al matrix. The formation of BCC structure makes the hardness of the solid solution layer up to 450HV, and the existence of the compound also increases the hardness of the Al matrix significantly.

Microstructure Characterization of Laser Clad TiVCrAlSi High Entropy Alloy Coating on Ti-6Al-4V Substrate

2010 ◽  
Vol 154-155 ◽  
pp. 621-625 ◽  
Author(s):  
Can Huang ◽  
Yong Zhong Zhang ◽  
Rui Vilar
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Alloy Coating ◽  
High Entropy Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Entropy ◽  
Bcc Phase ◽  
Scanning Electron

Due to the promising properties of high entropy alloy, TiVCrAlSi high entropy alloy coating was prepared on Ti-6Al-4V alloy surface by laser cladding. The microstructure and phase analysis of as-cast TiVCrAlSi alloy and laser clad coating were characterized by scanning electron microscope and X-ray diffraction. The results indicate that as-cast TiVCrAlSi alloy is mainly composed of (Ti,V)5Si3 and bcc phase. The laser clad coating is metallurgically bonded to the substrate with few pores and cracks. Laser clad TiVCrAlSi coating is also composed of (Ti,V)5Si3 and bcc phases.

Evolution of Microstructures and Properties of the AlxCrCuFeNi2 High-Entropy Alloys

2013 ◽  
Vol 745-746 ◽  
pp. 706-714 ◽  
Author(s):  
Sheng Guo Ma ◽  
Zhao Di Chen ◽  
Yong Zhang
Keyword(s):  
Phase Transformation ◽  
Cast Alloy ◽  
Alloy System ◽  
Molar Ratio ◽  
High Entropy Alloys ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Entropy ◽  
Heat Treated ◽  
Xrd Patterns

The microstructure and Vickers hardness of the AlxCrCuFeNi2(x=0.5, 1.0, and 2.0 in molar ratio) high-entropy alloys with as-cast and heat-treated states were investigated. X-ray diffraction (XRD) patterns suggested that for the Al0.5 alloy annealed at 900,an incomplete phase transformation from FCC to BCC occurred, while for the Al2.0 alloy as heated at 500 and 700, a converse phase transformation from BCC to FCC was obtained. Compared with the as-cast dendrites, after heat treatment, the microstructure of the alloys was obviously coarsened or spheroidized or homogenized, whereas the resultant hardness has almost not decreased even at high heating temperatures, which indicated the probability of ordering for this alloy system and thus effectively compensating the stress and structural relaxations. The Al2.0 alloy reached the maximum hardness value of 610 HV by annealing at 1100, which might be ascribed to the worm-like nanoprecipitations and the enhanced fraction of B2-ordered precipitations. By cold rolling, the Al0.5 alloy is able to reach the yield strength of 1055 MPa and the fracture strength of 1179 MPa, which was a significant improvement in comparison with the as-cast alloy.

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