scholarly journals MICROSTRUCTURE AND MECHANICAL PROPERTIES OF REFRACTORY HIGH-ENTROPY ALLOY HfMoNbTiCr

2021 ◽  
Vol 55 (2) ◽  
pp. 305-310
Author(s):  
Jiaojiao Yi ◽  
Lu Wang ◽  
Mingqin Xu ◽  
Lin Yang
Keyword(s):  
Cast Alloy ◽  
Vital Role ◽  
Stress Fields ◽  
Vacuum Arc ◽  
High Entropy Alloy ◽  
Laves Phases ◽  
High Entropy ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Bcc Phase

A new refractory alloy, HfMoNbTiCr, was obtained by replacing Zr with Cr or Mo in the HfMoNbTiZr or HfNbTiCrZr alloys using vacuum arc melting. The phase components, microstructures and compressive properties of the alloy in the as-cast and annealed states were investigated. The results showed that the phase components changed from a single BCC phase in HfMoNbTiZr and BCC+Laves phases in HfNbTiCrZr to multiple phases – primarily two BCC phases and two cubic Laves phases – in HfMoNbTiCr. Notably, the yield and ultimate compressive strength of the as-cast alloy significantly increased from 1719 and 1803 MPa to 1851 and 2489 MPa, without a decrease in the ductility. The stress fields induced by Mo and the Cr-containing Laves phases were responsible for the enhanced strength, while the stiff network-like framework composed of intrinsically-strong Cr-containing Laves phases may have played a vital role in retaining the ductility.

scholarly journals Effects of Zr Content on the Microstructure and Performance of TiMoNbZrx High-Entropy Alloys

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1315
Author(s):  
Gengbiao Chen ◽  
Yi Xiao ◽  
Xixi Ji ◽  
Xiubing Liang ◽  
Yongle Hu ◽  
...  
Keyword(s):  
Grain Size ◽  
Wear Resistance ◽  
Cast Alloy ◽  
Vacuum Arc ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
And Performance ◽  
Bcc Phase

TiMoNbZrx refractory high-entropy alloys were prepared by vacuum arc melting, and the influence of the Zr alloying element and its content on the phases, microstructure, mechanical properties, and wear resistance of TiMoNbZrx alloys was explored. It was found that the alloys after Zr addition were composed of a single BCC phase. Upon increasing the Zr content, the grain size of the as-cast alloy decreased first and then increased, and TiMoNbZr0.5 exhibited the smallest grain size. Adding an appropriate amount of Zr increased the strength and hardness of the alloys. TiMoNbZr0.5 exhibited the best wear resistance, with a friction coefficient of about 0.33. It also displayed the widest wear scar, the shallowest depth, and the greatest degree of wear on the grinding ball because of the formation of an oxide film during wear.

scholarly journals Microstructure and Mechanical Properties of Co-Cr-Mo-Si-Y-Zr High Entropy Alloy

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1456
Author(s):  
Karsten Glowka ◽  
Maciej Zubko ◽  
Paweł Świec ◽  
Krystian Prusik ◽  
Robert Albrecht ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Microstructure Analysis ◽  
Vacuum Arc ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Transmission Electron ◽  
Multi Phase ◽  
Principal Elements

Presented work was focused on obtaining new, up to our knowledge, non-described previously in the literature high entropy Co15Cr15Mo25Si15Y15Zr15 alloy to fill in the knowledge gap about the six-elemental alloys located in the adjacent to the center of phase diagrams. Material was obtained using vacuum arc melting. Phase analysis revealed the presence of a multi-phase structure. Scanning electron microscopy microstructure analysis revealed the existence of three different phases with partially dendritic structures. Chemical analysis showed that all phases consist of all six principal elements—however, with different proportions. Transmission electron microscopy microstructure analysis confirmed the presence of amorphous and nanocrystalline areas, as well as their mixture. For the studied alloy, any phase transformation and solid-state crystallization were not revealed in the temperature range from room temperature up to 1350 °C. Nanoindentation measurements revealed high nanohardness (13(2) GPa and 18(1) GPa for dendritic and interdendritic regions, respectively) and relatively low Young’s modulus (185(23) GPa and 194(9) GPa for dendritic and interdendritic regions, respectively) of the observed phases.

scholarly journals A Novel Low-Activation VCrFeTaxWx (x = 0.1, 0.2, 0.3, 0.4, and 1) High-Entropy Alloys with Excellent Heat-Softening Resistance

Entropy ◽  
2018 ◽  
Vol 20 (12) ◽  
pp. 951 ◽  
Author(s):  
Weiran Zhang ◽  
Peter Liaw ◽  
Yong Zhang
Keyword(s):  
Vickers Hardness ◽  
Vacuum Arc ◽  
Compressive Yield Strength ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Structural Applications ◽  
Typical Morphology ◽  
Bcc Phase

The microstructure, Vickers hardness, and compressive properties of novel low-activation VCrFeTaxWx (x = 0.1, 0.2, 0.3, 0.4, and 1) high-entropy alloys (HEAs) were studied. The alloys were fabricated by vacuum-arc melting and the characteristics of these alloys were explored. The microstructures of all the alloys exhibited a typical morphology of dendritic and eutectic structures. The VCrFeTa0.1W0.1 and VCrFeTa0.2W0.2 alloys are essentially single phase, consisting of a disordered body-centered-cubic (BCC) phase, whereas the VCrFeTa0.2W0.2 alloy contains fine, nanoscale precipitates distributed in the BCC matrix. The lattice parameters and compositions of the identified phases were investigated. The alloys have Vickers hardness values ranging from 546 HV0.2 to 1135 HV0.2 with the x ranging from 0.1 to 1, respectively. The VCrFeTa0.1W0.1 and VCrFeTa0.2W0.2 alloys exhibit compressive yield strengths of 1341 MPa and 1742 MPa, with compressive plastic strains of 42.2% and 35.7%, respectively. VCrFeTa0.1W0.1 and VCrFeTa0.2W0.2 alloys have excellent hardness after annealing for 25 h at 600–1000 °C, and presented compressive yield strength exceeding 1000 MPa with excellent heat-softening resistance at 600–800 °C. By applying the HEA criteria, Ta and W additions into the VCrFeTaW are proposed as a family of candidate materials for fusion reactors and high-temperature structural applications.

Microstructure and Properties of Multi-Component AlxCoCrFeNiTi0.5 High-Entropy Alloys

2013 ◽  
Vol 745-746 ◽  
pp. 775-780 ◽  
Author(s):  
Yong Dong ◽  
Yi Ping Lu ◽  
Jun Jia Zhang ◽  
Ting Ju Li
Keyword(s):  
Vacuum Arc ◽  
High Entropy Alloys ◽  
Test Results ◽  
High Entropy ◽  
Solid Solution Strengthening ◽  
Al Content ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Solution Strengthening ◽  
Bcc Phase

The multi-component AlxCoCrFeNiTi0.5 (x=0, 0.2, 0.5, 0.8, 1.0) high-entropy alloys were prepared by vacuum arc melting. The microstructure and mechanical properties were studied. It was found that the structure transformed from FCC into FCC + BCC + Laves, and finally into BCC with the increase of Al content. The compress test results showed that with the addition of aluminium from 0 to 1.0, the fraction strength increased while plasticity reduced. In the stain rates of 5×10-3/s and 1×10-3/s, when x=0.8 the fraction strength achieved maximum and x=0 the plastic was best, the strength of 2879MPa and 2433MPa, the strain of 0.21 and 0.22, respectively. The hardness increased obviously (from Hv479.1 to Hv692.7) when Bcc phase and Laves phase appeared. The analysis revealed that the strengthen mechanism was mainly composed of solid solution strengthening and precipitation strengthening.

scholarly journals Examination of Fracture Mechanisms in two Al – Ti – V – Cr – (Si) High Entropy Alloys

2021 ◽  
Vol 349 ◽  
pp. 02002
Author(s):  
Spyridon Chaskis ◽  
Dimitrios Kiousis ◽  
Pavlos Stavroulakis ◽  
Russell Goodall ◽  
Spyros Papaefthymiou
Keyword(s):  
Sem Analysis ◽  
Vacuum Arc ◽  
Fracture Mechanisms ◽  
High Entropy Alloys ◽  
Dendritic Microstructure ◽  
Slow Cooling ◽  
High Entropy ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Bcc Phase

This work focuses on the examination of two High Entropy Alloys (HEAs), the AlTiVCr and AlTiVCr–Si7.2, which have been observed to fail in a brittle manner directly after casting. Understanding the failure mechanics is a prerequisite for an alternative enhanced alloy design in order to prevent early failure without loading application. The specimens were produced using the Vacuum Arc Melting methodology in a protective argon atmosphere. The material was re–melted five times in combination with electromagnetic stirring in order to achieve a fully homogenized microstructure. Based on our findings, the failure occurred in the first 10 minutes after casting during slow cooling. Similarly, the same took place during thermal treatment after the third re–melting. The specimens were first prepared for optical (OM) and scanning electron microscopy (SEM) analysis. The material consists of a coarse dendritic microstructure as well as a retained BCC phase, which is the AlTiVCr phase. In the AlTiVCr – Si7.2 alloy a uniformly dispersed, angular intermetallic compound, namely the Ti5Si3, was identified, which increases the failure resistance of the material. Based on these findings the alloy will be redesigned.

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.

scholarly journals Synthesis of Spherical V-Nb-Mo-Ta-W High-Entropy Alloy Powder Using Hydrogen Embrittlement and Spheroidization by Thermal Plasma

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1296 ◽  
Author(s):  
Won-Hyuk Lee ◽  
Ki Beom Park ◽  
Kyung-Woo Yi ◽  
Sung Yong Lee ◽  
Kwangsuk Park ◽  
...  
Keyword(s):  
Hydrogen Embrittlement ◽  
Thermal Plasma ◽  
Fine Powder ◽  
Hydrogen Atmosphere ◽  
Vacuum Arc ◽  
Cubic Phase ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Inductively Coupled ◽  
Arc Melting

V-Nb-Mo-Ta-W high-entropy alloy (HEA), one of the refractory HEAs, is considered as a next-generation structural material for ultra-high temperature uses. Refractory HEAs have low castability and machinability due to their high melting temperature and low thermal conductivity. Thus, powder metallurgy becomes a promising method for fabricating components with refractory HEAs. Therefore, in this study, we fabricated spherical V-Nb-Mo-Ta-W HEA powder using hydrogen embrittlement and spheroidization by thermal plasma. The HEA ingot was prepared by vacuum arc melting and revealed to have a single body-centered cubic phase. Hydrogen embrittlement which could be achieved by annealing in a hydrogen atmosphere was introduced to get the ingot pulverized easily to a fine powder having an angular shape. Then, the powder was annealed in a vacuum atmosphere to eliminate the hydrogen from the hydrogenated HEA, resulting in a decrease in the hydrogen concentration from 0.1033 wt% to 0.0003 wt%. The angular shape of the HEA powder was turned into a spherical one by inductively-coupled thermal plasma, allowing to fabricate spherical V-Nb-Mo-Ta-W HEA powder with a d50 value of 28.0 μm.

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).

Mechanical Behavior of Novel Suction Cast Ti-Cu-Fe-Co-Ni High Entropy Alloys

2014 ◽  
Vol 790-791 ◽  
pp. 503-508 ◽  
Author(s):  
Sumanta Samal ◽  
Sutanuka Mohanty ◽  
Ajit Kumar Misra ◽  
Krishanu Biswas ◽  
B. Govind
Keyword(s):  
Mechanical Properties ◽  
Vacuum Arc ◽  
High Entropy Alloys ◽  
The Novel ◽  
Electron Microscopic ◽  
High Entropy ◽  
Alloy Chemistry ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Ductile Mode

The present investigation reports mechanical properties of novel multicomponent TixCuyFe20Co20Ni20 high entropy alloys (HEAs) with different alloy chemistry (x/y = 1/3, 3/7, 3/5, 9/11, 1, 11/9 and 3/2). The alloy cylinders were prepared by vacuum arc melting-cum-suction casting route. The detailed electron microscopic observations reveal the presence of three different solid solution phases; FCC (a1) phase, FCC (a2) phase and BCC (b) phase for all the investigated alloys, whereas ultrafine eutectic between FCC (a1) phase, and Ti2 (Co, Ni) - type Laves phase has been observed for the HEAs with x/y = 9/11, 1, 11/9 and 3/2. Room temperature compression test of the suction cast cylinders with aspect ratio of 2/1 has been conducted to obtain mechanical properties of the HEAs. The optimum combination of strength (~ 1.88 GPa) and plasticity (~ 21 %) is obtained for x/y = 9/11; indicating simultaneous improvement of strength as well as plasticity of the novel HEAs. Fractographic analysis of the fractured surfaces reveals mixed mode of fracture for x/y = 1/3, 3/7 and 3/5, ductile mode for x/y = 9/11 and 1, whereas brittle mode of fracture for x/y = 11/9 and 3/2.

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