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.

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.

Effect of Nitrogen Addition on Mechanical Property of Ti-Cr-Sn Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 2126-2129 ◽  
Author(s):  
Yuichi Nakahira ◽  
Tomonari Inamura ◽  
Hiroyasu Kanetaka ◽  
Shuichi Miyazaki ◽  
Hideki Hosoda
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Tensile Tests ◽  
Nitrogen Addition ◽  
N Addition ◽  
X Ray Diffraction ◽  
Solution Hardening ◽  
X Ray ◽  
Bcc Phase ◽  
Cold Workability

Effect of nitrogen (N) addition on mechanical properties of Ti-Cr-Sn alloy was investigated in this study. Ti-7mol%Cr-3mol%Sn was selected and less than 0.5wt% of N were systematically added. The alloys were characterized by optical microscopy, X-ray diffraction analysis and tensile tests at room temperature. The apparent phase was β (bcc) phase, whereas the presence of precipitates was confirmed in 0.5wt%N-added alloy only which did not exhibit sufficient cold workability. The grain size was not largely affected by N addition being less than 0.5wt%. Tensile tests revealed that less than 0.5wt%N addition improves the strength which is due to the solution hardening by interstitial N atoms.

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 Selected Properties of High Entropy Alloys Based on the AlFeMnNbNiTi System

2021 ◽  
Vol 60 (2) ◽  
pp. 71-80
Author(s):  
Konrad Chrzan ◽  
Kamil Cichocki ◽  
Piotr Adamczyk ◽  
Krzysztof Muszka
Keyword(s):  
Mechanical Properties ◽  
Solution Structure ◽  
Melting Process ◽  
High Entropy Alloys ◽  
X Ray ◽  
High Entropy ◽  
Protective Atmospheres ◽  
Process Heat ◽  
The Impact ◽  
Scanning Electron

The aim of this work was to study the impact of various fabrication methods used to prepare high entropy alloys based on the AlFeMnNbNiTi system. Chemical composition was customized to ensure a solid solution structure with precipitation of the Laves phase. The three manufactured alloys were prepared by melting, but with the use of various input materials and different furnaces in protective atmospheres. After the melting process, heat treatment was carried out. Structures of obtained materials were analyzed by means of a Scanning Electron Microscope (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) mapping. Mechanical properties were represented by Vickers hardness. In this paper, impact of the use of low purity input materials is shown, as well as differences in structure resulting from the utilization of different melting furnaces.

scholarly journals Interstitials in f.c.c. High Entropy Alloys

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 695 ◽  
Author(s):  
Ian Baker
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Yield Strength ◽  
Room Temperature ◽  
Sharp Decrease ◽  
Slight Reduction ◽  
Strength Increase ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Carbon Doped

The effects of interstitials on the mechanical properties of single-phase f.c.c. high entropy alloys (HEAs) have been assessed based on a review of the literature. It is found that in nearly all studies, carbon increases the yield strength, in some cases by more than in traditional alloys. This suggests that carbon can be an excellent way to strengthen HEAs. This strength increase is related to the lattice expansion from the carbon. The effects on other mechanical behavior is mixed. Most studies show a slight reduction in ductility due to carbon, but a few show increases in ductility accompanying the yield strength increase. Similarly, some studies show little or modest increases in work-hardening rate (WHR) due to carbon, whereas a few show a substantial increase. These latter effects are due to changes in deformation mode. For both undoped and carbon doped CoCrFeMnNi, the room temperature ductility decreases slightly with decreasing grain size until ~2–5 µm, below which the ductility appears to decrease rapidly. The room temperature WHR also appears to decrease with decreasing grain size in both undoped and carbon-doped CoCrFeMnNi and in nitrogen-doped medium entropy alloy NiCoCr, and, at least for the undoped HEA, shows a sharp decrease at grain sizes <2 µm. Interestingly, carbon has been shown to almost double the Hall–Petch strengthening in CoCrFeMnNi, suggesting the segregation of carbon to the grain boundaries. There have been few studies on the effects of other interstitials such as boron, nitrogen and hydrogen. It is clear that more research is needed on interstitials both to understand their effects on mechanical properties and to optimize their use.

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 structure of vacuum condensates of high entropy alloys of Cr–Fe–Co–Ni–Cu system on their mechanical properties

2020 ◽  
Vol 2020 (4) ◽  
pp. 16-22
Author(s):  
A.I. Ustinov ◽  
◽  
V.S. Skorodzievskii ◽  
S.A. Demchenkov ◽  
S.S. Polishchuk ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Vacuum Condensates

Powder plasma arc additive manufactured CoCrFeNi(SiC)x high-entropy alloys: Microstructure and mechanical properties

2021 ◽  
Vol 282 ◽  
pp. 128736 ◽  
Author(s):  
Qingkai Shen ◽  
Xiangdong Kong ◽  
Xizhang Chen ◽  
Xukai Yao ◽  
Vladislav B. Deev ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Entropy Alloys ◽  
Plasma Arc ◽  
High Entropy ◽  
Microstructure And Mechanical Properties
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