scholarly journals Effects of Process Control Agent Amount, Milling Time, and Annealing Heat Treatment on the Microstructure of AlCrCuFeNi High-Entropy Alloy Synthesized through Mechanical Alloying

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1493
Author(s):  
Negar Yazdani ◽  
Mohammad Toroghinejad ◽  
Ali Shabani ◽  
Pasquale Cavaliere
Keyword(s):  
Solid Solution ◽  
Process Control ◽  
Mechanical Alloying ◽  
Milling Time ◽  
Control Agent ◽  
High Entropy Alloy ◽  
Process Control Agent ◽  
Mechanically Alloyed ◽  
X Ray ◽  
High Entropy

This study was conducted to investigate the characteristics of the AlCrCuFeNi high-entropy alloy (HEA) synthesized through mechanical alloying (MA). In addition, effects of Process Control Agent (PCA) amount and milling time were investigated using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The results indicated that the synthesized AlCrCuFeNi alloy is a dual phase (FCC + BCC) HEA and the formation of the phases is strongly affected by the PCA amount. A high amount of PCA postponed the alloying process and prevented solid solution formation. Furthermore, with an increase in the PCA amount, lattice strain decreased, crystallite size increased, and the morphology of the mechanically alloyed particles changed from spherical to a plate-like shape. Additionally, investigation of thermal properties and annealing behavior at different temperatures revealed no phase transformation up to 400 °C; however, the amount of the phases changed. By increasing the temperature to 600 °C, a sigma phase (σ) and a B2-ordered solid solution formed; moreover, at 800 °C, the FCC phase decomposed into two different FCC phases.

Influence of Process Control Agent and Al Concentration on Synthesis and Phase Stability of a Mechanically Alloyed AlxCoCrFeMnNi High-Entropy Alloy

2021 ◽  
pp. 160770
Author(s):  
M.A. Ruiz-Esparza-Rodriguez ◽  
C.G. Garay-Reyes ◽  
I. Estrada-Guel ◽  
J.L. Hernández-Rivera ◽  
J.J. Cruz-Rivera ◽  
...  
Keyword(s):  
Process Control ◽  
Phase Stability ◽  
Control Agent ◽  
High Entropy Alloy ◽  
Process Control Agent ◽  
Mechanically Alloyed ◽  
High Entropy

Preparation of TiZrNbTa refractory high-entropy alloy powder by mechanical alloying with liquid process control agents

2020 ◽  
Vol 126 ◽  
pp. 106900 ◽  
Author(s):  
Yating Qiao ◽  
Yu Tang ◽  
Shun Li ◽  
Yicong Ye ◽  
Xiyue Liu ◽  
...  
Keyword(s):  
Process Control ◽  
Mechanical Alloying ◽  
Alloy Powder ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Liquid Process

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.

scholarly journals The Origins of High-Entropy Alloy Contamination Induced by Mechanical Alloying and Sintering

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1186
Author(s):  
Igor Moravcik ◽  
Antonin Kubicek ◽  
Larissa Moravcikova-Gouvea ◽  
Ondrej Adam ◽  
Vaclav Kana ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Milling Time ◽  
Microstructural Analysis ◽  
Steel Powder ◽  
Carbon Steels ◽  
Contamination Level ◽  
High Entropy Alloy ◽  
Influence Of Process Parameters ◽  
High Entropy ◽  
Oxygen Contamination

One of the prevailing problems for materials produced by powder metallurgy is contamination from various sources. This work deals with the influence of process parameters and presence of process control agents (PCA) on the contamination level of materials produced by means of mechanical alloying (MA) technology, densified with spark plasma sintering (SPS). The equiatomic CoCrFeNi high-entropy alloy (HEA) was manufactured by the said methodology. For clear comparison, the 316L austenitic steel powder was milled and densified with identical conditions as a reference material. Both materials were milled in argon and nitrogen atmospheres for various times from 5 to 30 h. Chemical analysis of contamination by carbon, oxygen, and nitrogen within the powder and bulk materials was carried out using combustion analyzers. The microstructural analysis of powders and bulk samples was carried out using scanning electron microscopy (SEM) with focus on contaminant phases. The results show that carbon contamination increases with milling time. It is caused by wear of milling vial and balls made from high-carbon steels. Increase of carbon content within consolidation using SPS was also observed. The oxygen contamination also increases with milling time. It is more pronounced in the CoCrFeNi alloy due to higher oxidation of powder surfaces prior to milling. Milling of powders using nitrogen atmosphere also causes an increase of nitrogen content in both HEA and AISI 316L. The use of PCA (ethanol) during milling even for a short time (30 min) causes significant increase of carbon and oxygen contamination. The ways to decrease contamination are discussed in the paper.

The synthesis of NbSi2 by mechanical alloying

1997 ◽  
Vol 12 (5) ◽  
pp. 1172-1175 ◽  
Author(s):  
Taiping Lou ◽  
Guojiang Fan ◽  
Bingzhe Ding ◽  
Zhuangqi Hu
Keyword(s):  
Solid Solution ◽  
Differential Scanning Calorimetry ◽  
Intermetallic Compound ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Temperature Rise ◽  
Milling Time ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

The stoichiometric intermetallic compound NbSi2 has been synthesized by mechanical alloying (MA) elemental Nb and Si powders. The alloying process has been investigated by means of x-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was found that the formation of the Nb2Si intermetallic compound occurs abruptly after 65 min of milling without any interruptions during the alloying process. However, short interruptions at a 5 min interval during ball milling result in a gradual reaction for the formation of the NbSi2 compound as well as a new metastable bcc structured solid solution. We conclude that the temperature rise during mechanical alloying plays an important role in initiating the abrupt reaction after an incubation milling time.

Synthesis and Evaluations of Microstructure Properties on Al-(50, 60, 70 mass%)Si Systems by Mechanical Alloying

2004 ◽  
Vol 449-452 ◽  
pp. 249-252 ◽  
Author(s):  
Jung Il Lee ◽  
Tae Whan Hong ◽  
Il Ho Kim ◽  
Soon Chul Ur ◽  
Young Geun Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Milling Time ◽  
Alloy System ◽  
Misfit Strain ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Transmission Electron ◽  
Nanocrystalline Structures

High silicon Al-Si alloy powders having nanocrystalline structures have been produced by mechanical alloying process. Microstructures in mechanically alloyed Al-Si powders were investigated by scanning electron microscopy and transmission electron microscopy. X-ray diffraction analyses were also carried out to characterize lattice constant, crystallite size and misfit strain. Effective milling time for the formation of nanocrystalline microstructure was thought to be approximately 12 hours, and the sizes of Al and Si crystallites in mechanically alloyed powders after longer than 12 hours of milling were reduced to about 30nm and 70nm respectively, in Al-70 mass% Si alloy system. The misfit strains increased with milling time up to 240 hours, and saturated to 5.73×10-3 and 4.39×10-3 for Al and Si crystallites, respectively.

Non-equiatomic W10Mo27Cr21Ti22Al20 high-entropy alloy produced by mechanical alloying and spark plasma sintering: Phase evolution and mechanical properties

2022 ◽  
pp. 146442072110510
Author(s):  
Hamed Naser-Zoshki ◽  
Ali-Reza Kiani-Rashid ◽  
Jalil Vahdati-Khaki
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
Elevated Temperatures ◽  
High Entropy Alloy ◽  
Solid Solution Phase ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma

In this work, non-equiatomic W10Mo27Cr21Ti22Al20 refractory high-entropy alloy (RHEA) was produced using mechanical alloying followed by spark plasma sintering. The phase formation, microstructure, and compressive mechanical properties of the alloy were studied. During mechanical alloying, a Body-centered cubic (BCC) solid solution phase with a particle size of less than 1 µm was obtained after 18 h ball milling. The microstructure of the sintered sample exhibits three distinct phases consisting of two solid solution phases BCC1 and BCC2 as well as fine TiCxOy precipitates distributed in them. The volume fractions of each phase were about 79%, 8%, and 13%, respectively. The sintered W10Mo27Cr21Ti22Al20 showed yield strengths of 2465, 1506, 405, and 290 MPa at room temperature 600, 1000, and 1200°C, respectively, which are about twice that of the same refractory high-entropy alloy produced by vacuum arc melting. At 1000 and 1200°C, the strength after yielding gradually increased to 970 and 718 MPa at a compressive strain of 60%. The studied refractory high-entropy alloy can have good potential in high-temperature applications due to its high specific strength at elevated temperatures compared to conventional Ni-based superalloys and most as-reported refractory high-entropy alloys.

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