scholarly journals Microstructure, Mechanical Properties and Tribological Properties of NiAlComposites Reinforced by CrMnFeCoNiHigh-Entropy Alloy

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1850 ◽  
Author(s):  
ShuQiang Zhou ◽  
XinYu Liu ◽  
Yi Xu
Keyword(s):  
Compressive Strength ◽  
Tribological Properties ◽  
Compressive Strain ◽  
High Entropy Alloy ◽  
Second Phase ◽  
Strengthening Effect ◽  
Phase Hardening ◽  
High Entropy ◽  
Mechanical And Tribological Properties ◽  
Fine Grain

NiAl-based composites reinforced by CrMnFeCoNi high-entropy alloy (HEA) particles were fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). The microstructure, mechanical, and tribological properties of the NiAl-HEA composites were investigated. Microstructural analyses show that after SPS, the HEA phase homogenously distributed in the NiAl matrix. Non-uniform diffusion of various elements occurred during the high temperature sintering process. Transmission electron microscope (TEM) observation of the composites revealed that many nano particle of Al2O3 generated at the grain boundary. The yield strength significantly increased after adding HEA particles. The compressive strength of the composites increased with the contents of HEA increasing, which should be attributed to the second phase hardening effect of HEA particles and fine grain strengthening effect. The composite of 10 wt.% HEA exhibited significant room temperature compressive properties, with the ultimate compressive strength of 2692 MPa and the compressive strain of 34.2%, respectively. The results of the wear tests show that the addition of HEA will reduce the wear resistance of composites to some extent and slightly increase the coefficients of friction (COFs) of the composites.

scholarly journals Development of Novel Lightweight Al-Rich Quinary Medium-Entropy Alloys with High Strength and Ductility

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4223
Author(s):  
Po-Sung Chen ◽  
Yu-Chin Liao ◽  
Yen-Ting Lin ◽  
Pei-Hua Tsai ◽  
Jason S. C. Jang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Compressive Strain ◽  
High Strength ◽  
Fine Tuning ◽  
Face Centered Cubic ◽  
Transportation Industry ◽  
High Entropy ◽  
Good Potential ◽  
Face Centered

Most high-entropy alloys and medium-entropy alloys (MEAs) possess outstanding mechanical properties. In this study, a series of lightweight nonequiatomic Al50–Ti–Cr–Mn–V MEAs with a dual phase were produced through arc melting and drop casting. These cast alloys were composed of body-centered cubic and face-centered cubic phases. The density of all investigated MEAs was less than 5 g/cm3 in order to meet energy and transportation industry requirements. The effect of each element on the microstructure evolution and mechanical properties of these MEAs was investigated. All the MEAs demonstrated outstanding compressive strength, with no fractures observed after a compressive strain of 20%. Following the fine-tuning of the alloy composition, the Al50Ti20Cr10Mn15V5 MEA exhibited the most compressive strength (~1800 MPa) and ductility (~34%). A significant improvement in the mechanical compressive properties was achieved (strength of ~2000 MPa, strain of ~40%) after annealing (at 1000 °C for 0.5 h) and oil-quenching. With its extremely high specific compressive strength (452 MPa·g/cm3) and ductility, the lightweight Al50Ti20Cr10Mn15V5 MEA demonstrates good potential for energy or transportation applications in the future.

scholarly journals Effect of Copper Addition on the AlCoCrFeNi High Entropy Alloys Properties via the Electroless Plating and Powder Metallurgy Technique

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 540
Author(s):  
Mohamed Ali Hassan ◽  
Hossam M. Yehia ◽  
Ahmed S. A. Mohamed ◽  
Ahmed Essa El-Nikhaily ◽  
Omayma A. Elkady
Keyword(s):  
Compressive Strength ◽  
Powder Metallurgy ◽  
Atomic Radius ◽  
The Other ◽  
High Entropy Alloy ◽  
Coating Process ◽  
High Entropy Alloys ◽  
Powder Metallurgy Technique ◽  
Copper Metal ◽  
High Entropy

To improve the AlCoCrFeNi high entropy alloys’ (HEAs’) toughness, it was coated with different amounts of Cu then fabricated by the powder metallurgy technique. Mechanical alloying of equiatomic AlCoCrFeNi HEAs for 25 h preceded the coating process. The established powder samples were sintered at different temperatures in a vacuum furnace. The HEAs samples sintered at 950˚C exhibit the highest relative density. The AlCoCrFeNi HEAs model sample was not successfully produced by the applied method due to the low melting point of aluminum. The Al element’s problem disappeared due to encapsulating it with a copper layer during the coating process. Because the atomic radius of the copper metal (0.1278 nm) is less than the atomic radius of the aluminum metal (0.1431 nm) and nearly equal to the rest of the other elements (Co, Cr, Fe, and Ni), the crystal size powder and fabricated samples decreased by increasing the content of the Cu wt%. On the other hand, the lattice strain increased. The microstructure revealed that the complete diffusion between the different elements to form high entropy alloy material was not achieved. A dramatic decrease in the produced samples’ hardness was observed where it decreased from 403 HV at 5 wt% Cu to 191 HV at 20 wt% Cu. On the contrary, the compressive strength increased from 400.034 MPa at 5 wt% Cu to 599.527 MPa at 15 wt% Cu with a 49.86% increment. This increment in the compressive strength may be due to precipitating the copper metal on the particles’ surface in the nano-size, reducing the dislocations’ motion, increasing the stiffness of produced materials. The formability and toughness of the fabricated materials improved by increasing the copper’s content. The thermal expansion has increased gradually by increasing the Cu wt%.

Influence of alumina whisker or nano-carbon contents on the microstructure and mechanical properties of CuZrTiAlNi refractory high entropy alloy composites

2020 ◽  
Vol 62 (7) ◽  
pp. 678-688
Author(s):  
X. Jiang ◽  
J. Chen ◽  
H. Sun ◽  
Z. Shao
Keyword(s):  
Mechanical Properties ◽  
Load Transfer ◽  
Microwave Sintering ◽  
Fracture Morphology ◽  
Strengthening Mechanism ◽  
Cold Isostatic Pressing ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Structure And Property ◽  
Fine Grain

Abstract High-entropy alloy composites were fabricated by ball milling, cold isostatic pressing and microwave sintering to which were added varied contents of Al2O3 whiskers, La-Ce, and carbon nanotubes-graphene, respectively. The structure and mechanical properties of the composites were investigated by X-ray diffraction, scanning electron microscopy and a microhardness tester. The high-entropy alloy and composites show amorphous phases and some crystalline phases. Accordingly, the addition of the reinforcement phase can refine the grain size. The formation mechanism of the phase is mainly related to the factors of mixing entropy, enthalpy, differences in atomic size, and the structure and property of the elements. The hardness of the composites is higher than that of the alloy (437.5 HV), and those composites reinforced by 0.5 wt.-% nanotubes- 0.5 wt.-% graphene are the highest (593.99 HV). The fracture morphology of the Al2O3 whisker reinforced composite shows a river pattern, indicating brittle cleavage. According to the research results, it can be concluded that the strengthening mechanism of the high entropy alloy composites mainly reflects fine grain strengthening and load transfer, and the toughening mechanism mainly crack bridging and a pulling out of the reinforcing phase.

scholarly journals Effects of Silicon Content on the Microstructures and Mechanical Properties of (AlCrTiZrV)-Six-N High-Entropy Alloy Films

Entropy ◽  
2019 ◽  
Vol 21 (1) ◽  
pp. 75 ◽  
Author(s):  
Jingrui Niu ◽  
Wei Li ◽  
Ping Liu ◽  
Ke Zhang ◽  
Fengcang Ma ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Amorphous Phase ◽  
Silicon Content ◽  
High Entropy Alloy ◽  
Strengthening Effect ◽  
Nanocomposite Structure ◽  
High Entropy ◽  
Nanocrystalline Structures ◽  
Microstructures And Mechanical Properties

A series of (AlCrTiZrV)-Six-N films with different silicon contents were deposited on monocrystalline silicon substrates by direct-current (DC) magnetron sputtering. The films were characterized by the X-ray diffractometry (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and nano-indentation techniques. The effects of the silicon content on the microstructures and mechanical properties of the films were investigated. The experimental results show that the (AlCrTiZrV)N films grow in columnar grains and present a (200) preferential growth orientation. The addition of the silicon element leads to the disappearance of the (200) peak, and the grain refinement of the (AlCrTiZrV)-Six-N films. Meanwhile, the reticular amorphous phase is formed, thus developing the nanocomposite structure with the nanocrystalline structures encapsulated by the amorphous phase. With the increase of the silicon content, the mechanical properties first increase and then decrease. The maximal hardness and modulus of the film reach 34.3 GPa and 301.5 GPa, respectively, with the silicon content (x) of 8% (volume percent). The strengthening effect of the (AlCrTiZrV)-Six-N film can be mainly attributed to the formation of the nanocomposite structure.

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