A novel bulk eutectic high-entropy alloy with outstanding as-cast specific yield strengths at elevated temperatures

2021 ◽  
Vol 204 ◽  
pp. 114132
Author(s):  
Mingliang Wang ◽  
Yiping Lu ◽  
Tongmin Wang ◽  
Chuan Zhang ◽  
Zhiqiang Cao ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Specific Yield ◽  
High Entropy Alloy ◽  
High Entropy

scholarly journals Laser Beam Welding of a Low Density Refractory High Entropy Alloy

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1351 ◽  
Author(s):  
Evgeniya Panina ◽  
Nikita Yurchenko ◽  
Sergey Zherebtsov ◽  
Nikita Stepanov ◽  
Gennady Salishchev ◽  
...  
Keyword(s):  
Laser Beam ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Laser Beam Welding ◽  
Base Material ◽  
Laves Phase ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Grains Refinement ◽  
Cast Condition

The effect of laser beam welding on the structure and properties of a Ti1.89NbCrV0.56 refractory high entropy alloy was studied. In particular, the effect of different pre-heating temperatures was examined. Due to the low ductility of the material, laser beam welding at room temperature resulted in the formations of hot cracks. Sound butt joints without cracks were produced using pre-heating to T ≥ 600 °C. In the initial as-cast condition, the alloy consisted of coarse bcc grains with a small amount of lens-shaped C15 Laves phase particles. A columnar microstructure was formed in the welds; the thickness of the grains increased with the temperature of pre-heating before welding. The Laves phase particles were formed in the seams after welding at 600 °C or 800 °C, however, these particles were not observed after welding at room temperature or at 400 °C. Soaking at elevated temperatures did not change the microstructure of the base material considerably, however, “additional” small Laves particles formed at 600 °C or 800 °C. Tensile test of welded specimens performed at 750 °C resulted in the fracture of the base material because of the higher hardness of the welds. The latter can be associated with the bcc grains refinement in the seams.

scholarly journals Element Effects on High-Entropy Alloy Vacancy and Heterogeneous Lattice Distortion Subjected to Quasi-equilibrium Heating

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
E-Wen Huang ◽  
Hung-Sheng Chou ◽  
K. N. Tu ◽  
Wei-Song Hung ◽  
Tu-Ngoc Lam ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Lattice Structure ◽  
High Entropy Alloy ◽  
Quasi Equilibrium ◽  
X Ray ◽  
Structure Relaxation ◽  
High Entropy ◽  
Spatially Resolved ◽  
Formation Enthalpies ◽  
Different Characteristics

Abstract We applied Simmons–Balluffi methods, positron measurements, and neutron diffraction to estimate the vacancy of CoCrFeNi and CoCrFeMnNi high-entropy alloys (HEAs) using Cu as a benchmark. The corresponding formation enthalpies and associated entropies of the HEAs and Cu were calculated. The vacancy-dependent effective free volumes in both CoCrFeNi and CoCrFeMnNi alloys are greater than those in Cu, implying the easier formation of vacancies by lattice structure relaxation of HEAs at elevated temperatures. Spatially resolved synchrotron X-ray measurements revealed different characteristics of CoCrFeNi and CoCrFeMnNi HEAs subjected to quasi-equilibrium conditions at high temperatures. Element-dependent behavior revealed by X-ray fluorescence (XRF) mapping indicates the effect of Mn on the Cantor Alloy.

scholarly journals A novel equiaxed eutectic high-entropy alloy with excellent mechanical properties at elevated temperatures

2020 ◽  
Vol 8 (10) ◽  
pp. 373-382 ◽  
Author(s):  
Liuliu Han ◽  
Xiandong Xu ◽  
Zhiming Li ◽  
Bin Liu ◽  
C. T. Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
High Entropy Alloy ◽  
High Entropy

scholarly journals Effect of V and Ti on the Oxidation Resistance of WMoTaNb Refractory High-Entropy Alloy at High Temperatures

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 41
Author(s):  
Shuaidan Lu ◽  
Xiaoxiao Li ◽  
Xiaoyu Liang ◽  
Wei Yang ◽  
Jian Chen
Keyword(s):  
Oxidation Resistance ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Early Stage ◽  
Mass Gain ◽  
High Entropy Alloy ◽  
High Entropy Alloys ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Entropy

Alloying with V and Ti elements effectively improves the strength of WMoTaNb refractory high entropy alloys (RHEAs) at elevated temperatures. However, their effects on the oxidation resistance of WMoTaNb RHEAs are unknown, which is vitally important to their application at high temperatures. In this work, the effect of V and Ti on the oxidation behavior of WMoTaNb RHEA at 1000 °C was investigated using a thermogravimetric system, X-ray diffraction and scanning electron microscopy. The oxidation of all alloys was found to obey a power law passivating oxidation at the early stage. The addition of V aggravates the volatility of V2O5, MoO3 and WO3, and leads to disastrous internal oxidation. The addition of Ti reduces the mass gain in forming the full coverage of passivating scale and prolongs the passivation duration of alloys.

Vacuum tribological behaviors of CoCrFeNi high entropy alloy at elevated temperatures

Wear ◽  
2020 ◽  
Vol 456-457 ◽  
pp. 203368 ◽  
Author(s):  
Yushan Geng ◽  
Jiao Chen ◽  
Hui Tan ◽  
Jun Cheng ◽  
Jun Yang ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Tribological Behaviors

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.

High-Entropy Alloys – A New Era of Exploitation

2007 ◽  
Vol 560 ◽  
pp. 1-9 ◽  
Author(s):  
Jien Wei Yeh ◽  
Yu Liang Chen ◽  
Su Jien Lin ◽  
Swe Kai Chen
Keyword(s):  
Elevated Temperatures ◽  
Second Law Of Thermodynamics ◽  
Simple Relation ◽  
Atomic Diffusion ◽  
High Entropy Alloy ◽  
New Era ◽  
High Entropy ◽  
Wide Range ◽  
Mechanisms Of Formation ◽  
And Control

A high-entropy alloy (HEA) has been defined by us to have at least five principal elements, each of which has an atomic concentration between 5% and 35%. In the exploration on this new alloy field, we find that HEAs are quite simple to analyze and control, and they might be processed as traditional alloys. There exist many opportunities to create novel alloys, better than traditional ones in a wide range of applications. In this paper, we review the basic microstructural features of HEAs and discuss the mechanisms of formation. Instead of multiple intermetallic phases, the HEAs tend to form simple solid solution phases mainly of cubic crystal structure, especially at elevated temperatures. This tendency is explained by the high entropy effect based on the simple relation: (Gmix = (Hmix – T(Smix, and the second law of thermodynamics. Moreover, nanostructures and amorphous phases are easily formed in HEAs. This tendency is explained by kinetics theory as due to slow atomic diffusion.

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