Coherent precipitation and stability of cuboidal nanoparticles in body-centered-cubic Al0.4Nb0.5Ta0.5TiZr0.8 refractory high entropy alloy

2021 ◽  
Vol 190 ◽  
pp. 40-45
Author(s):  
Qing Wang ◽  
Jincan Han ◽  
Yufeng Liu ◽  
Zhongwei Zhang ◽  
Chuang Dong ◽  
...  
Author(s):  
F. J. Wang ◽  
Y. Zhang ◽  
G. L. Chen ◽  
H. A. Davies

High entropy alloys are usually defined as the kind of alloys with at least five principle components, each component has the equi-atomic ratio or near equi-atomic ratio, and the high entropy alloys can have very high entropy of mixing, forming simple solid solution rather than many complex intermediate phases. In this paper, the size effects on the microstructure and mechanical behaviors of a high entropy alloy of AlCoCrFeNi was studied by preparing as-cast rod samples with different diameters. The alloy independent of cast diameter samples has the same phase of body centered cubic solid solution. With decreasing casting diameter, both the strength and the plasticity are increased slightly.


Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1250 ◽  
Author(s):  
Yonggang Tong ◽  
Peibu Qi ◽  
Xiubing Liang ◽  
Yongxiong Chen ◽  
Yongle Hu ◽  
...  

Different-shaped ultrafine MoNbTaW high-entropy alloy powders were firstly prepared by a convenient mechanical alloying method. The phase composition and microstructure of the powders were characterized. The powders are ultrafine with nano-sized grains and a good homogeneous microstructure. All the powders have a single body-centered cubic solid solution phase and form the high-entropy alloy during mechanical alloying. These powders with different shapes are quite attractive for developing high-performance MoNbTaW high-entropy alloy bulk and coatings combined with a following sintering, spraying, or additive manufacturing technique.


Coatings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 373 ◽  
Author(s):  
Yiku Xu ◽  
Zhiyuan Li ◽  
Jianru Liu ◽  
Yongnan Chen ◽  
Fengying Zhang ◽  
...  

High-entropy alloy (HEA) coatings of CoCrFeNiTiAlx (x = 0, 0.5, 1, 1.5, 2) were prepared on the surface of AISI1045 steel by laser cladding. The effects of the Al content on the microstructure, composition, phase constitution, and wear and corrosion resistance of the coatings were investigated. The results showed that when increasing the Al element content from 0 to 0.5, the phase constitution of the CoCrFeNiTiAlx coating changed from a single Face-centered cubic (FCC) phase to Body-centered cubic 1 (BCC1) and Body-centered cubic 2 (BCC2) phases, with a small amount of Laves phase, which obviously improved the friction and corrosion resistance of the coating. With further enhancing of the Al content, the amount of BCC1 phase increased, while the BCC2 phase and the Laves phase decreased. The CoCrFeNiTiAl2 HEA coating transformed into a single BCC1 phase, with retrogressive wear and corrosion resistance. It was found that the Al0.5 alloy coating exhibits excellent wear resistance, high hardness, and corrosion resistance in a 3.5 wt.% NaCl solution. Furthermore, the effect of the Al content on the microstructure, phase, and the relating properties of the CoCrFeNiTiAlx HEA coatings is also discussed.


Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3508 ◽  
Author(s):  
Liu ◽  
Huang ◽  
Chuang ◽  
Chou ◽  
Wei ◽  
...  

In this study, the effects of spinodal decomposition on the microstructures and mechanical properties of a TiZrNbTa alloy are investigated. The as-cast TiZrNbTa alloy possesses dual phases of TiZr-rich inter-dendrite (ID) and NbTa-rich dendrite (DR) domains, both of which have a body-centered cubic (BCC) structure. In the DRs of the as-cast alloy, the α and ω precipitates are found to be uniformly distributed. After homogenization at 1100 °C for 24 h followed by water quenching, spinodal decomposition occurs and an interconnected structure with a wavelength of 20 nm is formed. The α and ω precipitates remained in the structure. Such a fine spinodal structure strengthens the alloy effectively. Detailed strengthening calculations were conducted in order to estimate the strengthening contributions from the α and ω precipitates, as well as the spinodal decomposition microstructure.


Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 485 ◽  
Author(s):  
Yueli Ma ◽  
Shiwei Wu ◽  
Yuefei Jia ◽  
Pengfei Hu ◽  
Yeqiang Bu ◽  
...  

A NbTiHfZr high-entropy alloy (HEA) with a main phase of body-centered cubic structure is fabricated. Some hexagonal closed-packed (hcp) precipitates are observed in this alloy. A thermal-mechanical process, i.e., cold-rolling followed by annealing, can manipulate the volume fraction of the hcp nano-precipitates that can enhance strength and ductility. The enhancement is tailorable as a function of the volume fraction of the hcp nano-precipitate. The results indicate that the strength-ductility property can be manipulated via adjusting post-deformation heat-treatment methods, which provide a new strategy by utilizing metastability at high-temperature to design high strength refractory HEAs (RHEAs) without lost in ductility.


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