scholarly journals A critical review of the mechanical properties of CoCrNi-based medium-entropy alloys

2022 ◽  
Author(s):  
Dingfeng Xu ◽  
Mingliang Wang ◽  
Tianxin Li ◽  
Xiangsai Wei ◽  
Yiping Lu
Keyword(s):  
Mechanical Properties ◽  
First Generation ◽  
Mechanical Performance ◽  
Chemical Compositions ◽  
High Entropy ◽  
Tensile Response ◽  
Short Range Ordering ◽  
Critical Resolved Shear Stress ◽  
Development Prospects ◽  
Strength And Ductility

The CoCrFeMnNi alloy is one of the most notable first-generation high-entropy alloys and is also known as a Cantor alloy. This alloy was first proposed in 2004 and shows promising performance at cryogenic temperatures (CTs). Subsequent research has indicated that the equiatomic ternary CoCrNi medium-entropy alloy (MEA), as a subset of the Cantor alloy family, has better mechanical properties than the CoCrFeMnNi alloy. Interestingly, both the strength and ductility of the CoCrNi MEA are higher at CTs than at room temperature. CoCrNi-based alloys have attracted considerable attention in the metallic materials community and it is therefore important to generalize and summarize the latest progress in CoCrNi-based MEA research. The present review initially briefly introduces the discovery of the CoCrNi MEA. Subsequently, its tensile response and deformation mechanisms are summarized. In particular, the effects of parameters, such as critical resolved shear stress, stacking fault energy and short-range ordering, on the deformation behavior are discussed in detail. The methods for strengthening the CoCrNi MEA are then reviewed and divided into two categories, namely, modifying microstructures and adjusting chemical compositions. In addition, the mechanical performance of CoCrNi-based MEAs, including their dynamic shear properties, creep behavior and fracture toughness, is also deliberated. Finally, the development prospects of CoCrNi-based MEAs are proposed.

scholarly journals Simultaneously enhancing the ultimate strength and ductility of high-entropy alloys via short-range ordering

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shuai Chen ◽  
Zachary H. Aitken ◽  
Subrahmanyam Pattamatta ◽  
Zhaoxuan Wu ◽  
Zhi Gen Yu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ultimate Strength ◽  
Short Range ◽  
Density Functional ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Body Center Cubic ◽  
Short Range Ordering ◽  
Composite Microstructure ◽  
Strength And Ductility

AbstractSimultaneously enhancing strength and ductility of metals and alloys has been a tremendous challenge. Here, we investigate a CoCuFeNiPd high-entropy alloy (HEA), using a combination of Monte Carlo method, molecular dynamic simulation, and density-functional theory calculation. Our results show that this HEA is energetically favorable to undergo short-range ordering (SRO), and the SRO leads to a pseudo-composite microstructure, which surprisingly enhances both the ultimate strength and ductility. The SRO-induced composite microstructure consists of three categories of clusters: face-center-cubic-preferred (FCCP) clusters, indifferent clusters, and body-center-cubic-preferred (BCCP) clusters, with the indifferent clusters playing the role of the matrix, the FCCP clusters serving as hard fillers to enhance the strength, while the BCCP clusters acting as soft fillers to increase the ductility. Our work highlights the importance of SRO in influencing the mechanical properties of HEAs and presents a fascinating route for designing HEAs to achieve superior mechanical properties.

scholarly journals Tribological and Mechanical Properties of Multicomponent CrVTiNbZr(N) Coatings

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 41
Author(s):  
Yin-Yu Chang ◽  
Cheng-Hsi Chung
Keyword(s):  
Mechanical Properties ◽  
Nitrogen Content ◽  
Adhesion Strength ◽  
Mechanical Performance ◽  
Bulk Material ◽  
High Entropy Alloy ◽  
Composition Gradient ◽  
Multilayered Structures ◽  
High Entropy ◽  
Alloy Target

Multi-element material coating systems have received much attention for improving the mechanical performance in industry. However, they are still focused on ternary systems and seldom beyond quaternary ones. High entropy alloy (HEA) bulk material and thin films are systems that are each comprised of at least five principal metal elements in equally matched proportions, and some of them are found possessing much higher strength than traditional alloys. In this study, CrVTiNbZr high entropy alloy and nitrogen contained CrVTiNbZr(N) nitride coatings were synthesized using high ionization cathodic-arc deposition. A chromium-vanadium alloy target, a titanium-niobium alloy target and a pure zirconium target were used for the deposition. By controlling the nitrogen content and cathode current, the CrNbTiVZr(N) coating with gradient or multilayered composition control possessed different microstructures and mechanical properties. The effect of the nitrogen content on the chemical composition, microstructure and mechanical properties of the CrVTiNbZr(N) coatings was investigated. Compact columnar microstructure was obtained for the synthesized CrVTiNbZr(N) coatings. The CrVTiNbZrN coating (HEAN-N165), which was deposited with nitrogen flow rate of 165 standard cubic centimeters per minute (sccm), exhibited slightly blurred columnar and multilayered structures containing CrVN, TiNbN and ZrN. The design of multilayered CrVTiNbZrN coatings showed good adhesion strength. Improvement of adhesion strength was obtained with composition-gradient interlayers. The CrVTiNbZrN coating with nitrogen content higher than 50 at.% possessed the highest hardness (25.2 GPa) and the resistance to plastic deformation H3/E*2 (0.2 GPa) value, and therefore the lowest wear rate was obtained because of high abrasion wear resistance.

scholarly journals The Effect of Phase Separation on the Mechanical Behavior of the Co–Cr–Cu–Fe–Ni High-Entropy Alloy

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6523
Author(s):  
Heling Liu ◽  
Chuanxiao Peng ◽  
Xuelian Li ◽  
Shenghai Wang ◽  
Li Wang
Keyword(s):  
Mechanical Properties ◽  
Phase Separation ◽  
Grain Boundaries ◽  
Deformation Behavior ◽  
Grain Boundary Sliding ◽  
Dynamics Simulation ◽  
Uniaxial Tensile ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Critical Resolved Shear Stress

Phase separation phenomena in high-entropy alloys (HEAs) have attracted much attention since their discovery, but little attention has been given to the dynamics of the deformation mechanism of this kind of HEA during uniaxial tension, which limits their widespread and practical utility. In this work, molecular dynamics simulation was used to study the effect of phase separation on the mechanical properties of an HEA under uniaxial tensile loading. Moreover, the associated deformation behavior of the Co–Cr–Cu–Fe–Ni HEA was investigated at the nanoscale. Models with Cu-rich grain boundaries or grains were constructed. The results showed that Cu-rich grain boundaries or grains lowered the strength of the Co–Cr–Cu–Fe–Ni HEA, and Cu-rich grain boundaries significantly reduced ductility. This change of mechanical properties was closely associated with a deformation behavior. Furthermore, the deformation behavior was affected by the critical resolved shear stress of Cu-rich and Cu-depleted regions and the uneven stress distribution caused by phase separation. In addition, dislocation slipping and grain boundary sliding were the main mechanisms of plastic deformation in the Co–Cr–Cu–Fe–Ni HEA.

scholarly journals Additive Manufacturing of High-Entropy Alloys: A Review

Entropy ◽  
2018 ◽  
Vol 20 (12) ◽  
pp. 937 ◽  
Author(s):  
Shuying Chen ◽  
Yang Tong ◽  
Peter Liaw
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
High Efficiency ◽  
Mechanical Performance ◽  
Heating Temperature ◽  
Intermetallic Phase ◽  
Solid Solution Phase ◽  
High Entropy Alloys ◽  
Scanning Method ◽  
High Entropy

Owing to the reduced defects, low cost, and high efficiency, the additive manufacturing (AM) technique has attracted increasingly attention and has been applied in high-entropy alloys (HEAs) in recent years. It was found that AM-processed HEAs possess an optimized microstructure and improved mechanical properties. However, no report has been proposed to review the application of the AM method in preparing bulk HEAs. Hence, it is necessary to introduce AM-processed HEAs in terms of applications, microstructures, mechanical properties, and challenges to provide readers with fundamental understanding. Specifically, we reviewed (1) the application of AM methods in the fabrication of HEAs and (2) the post-heat treatment effect on the microstructural evolution and mechanical properties. Compared with the casting counterparts, AM-HEAs were found to have a superior yield strength and ductility as a consequence of the fine microstructure formed during the rapid solidification in the fabrication process. The post-treatment, such as high isostatic pressing (HIP), can further enhance their properties by removing the existing fabrication defects and residual stress in the AM-HEAs. Furthermore, the mechanical properties can be tuned by either reducing the pre-heating temperature to hinder the phase partitioning or modifying the composition of the HEA to stabilize the solid-solution phase or ductile intermetallic phase in AM materials. Moreover, the processing parameters, fabrication orientation, and scanning method can be optimized to further improve the mechanical performance of the as-built-HEAs.

Activities of Non-Basal Slips in Rolled Mg-Li and Mg-Ce Alloys Sheets

2021 ◽  
Vol 1016 ◽  
pp. 917-921
Author(s):  
Haruka Miyano ◽  
Keisuke Takemoto ◽  
Hiromoto Kitahara ◽  
Shinji Ando
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Tensile Tests ◽  
Lithium Content ◽  
Slip Systems ◽  
Alloying Additions ◽  
Alloy Strength ◽  
Critical Resolved Shear Stress ◽  
The Relationship ◽  
Strength And Ductility

In this study, tensile tests of rolled Mg-Li alloy and Mg-Ce alloy sheets were carried out at room temperature to investigate effects of alloying additions on the relationship between mechanical properties and activities of slip systems in magnesium polycrystals. In Mg-Li alloy, ductility increased while strength decreased by lithium addition. Frequency of non-basal slips increased with increasing lithium content. In Mg-Ce alloy, strength and ductility were similar pure magnesium, and non-basal slips were hardly activated. Since critical resolved shear stress of non-basal slips were decreased by lithium addition, ductility of magnesium was increased while its strength was decreased.

scholarly journals Prediction on Mechanical Properties of Non-Equiatomic High-Entropy Alloy by Atomistic Simulation and Machine Learning

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 922
Author(s):  
Liang Zhang ◽  
Kun Qian ◽  
Björn W. Schuller ◽  
Yasushi Shibuta
Keyword(s):  
Machine Learning ◽  
Mechanical Properties ◽  
Md Simulation ◽  
Mechanical Performance ◽  
Binary Classification ◽  
Computational Simulation ◽  
Engineering Application ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Learning Machine

High-entropy alloys (HEAs) with multiple constituent elements have been extensively studied in the past 20 years, due to their promising engineering application. Previous experimental and computational studies of HEAs focused mainly on equiatomic or near equiatomic HEAs. However, there is probably far more treasure in those non-equiatomic HEAs with carefully designed composition. In this study, the molecular dynamics (MD) simulation combined with machine learning (ML) methods was used to predict the mechanical properties of non-equiatomic CuFeNiCrCo HEAs. A database was established based on a tensile test of 900 HEA single-crystal samples by MD simulation. Eight ML models were investigated and compared for the binary classification learning tasks, ranging from shallow models to deep models. It was found that the kernel-based extreme learning machine (KELM) model outperformed others for the prediction of yield stress and Young’s modulus. The accuracy of the KELM model was further verified by the large-sized polycrystal HEA samples. The results show that computational simulation combined with ML methods is an efficient way to predict the mechanical performance of HEAs, which provides new ideas for accelerating the development of novel alloy materials for engineering applications.

Mechanical Properties of Roll Extruded Nuclear Reactor Piping

1976 ◽  
Vol 98 (2) ◽  
pp. 105-110
Author(s):  
J. M. Steichen ◽  
R. L. Knecht
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Crack Propagation ◽  
Strain Rate ◽  
Nuclear Reactor ◽  
Large Diameter ◽  
Tensile Tests ◽  
Test Facility ◽  
Chemical Compositions ◽  
Strength And Ductility

The elevated temperature mechanical properties of large diameter (28 in.) seamless pipe produced by roll extrusion for use as primary piping for sodium coolant in the Fast Flux Test Facility (FFTF) have been characterized. The three heats of type 316H stainless steel piping material used in this study exhibited very consistent mechanical properties and chemical compositions. Tensile and creep-rupture properties exceed values on which the allowable stresses for ASME Code Case 1592 on Nuclear Components in Elevated Temperature Service were based. Tensile strength and ductility were essentially unchanged by aging in static sodium at 1050°F (566°C) for times to 10,000 hr. High strain rate tensile tests showed that tensile properties were insensitive to strain rate at temperatures to 900°F (482°C) and that for temperatures of 1050°F (566°C) and above both strength and ductility significantly increased with increasing strain rate. Fatigue-crack propagation properties were comparable to results obtained on plate material and no differences in crack propagation were found between axial and circumferential orientations.

Short-range ordering and its effects on mechanical properties of high-entropy alloys

2021 ◽  
Vol 62 ◽  
pp. 214-220 ◽  
Author(s):  
Yuan Wu ◽  
Fei Zhang ◽  
Xiaoyuan Yuan ◽  
Hailong Huang ◽  
Xiaocan Wen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Short Range ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Short Range Ordering

The Impact of Corrosion on the Mechanical Behavior of Bolt

2010 ◽  
Vol 168-170 ◽  
pp. 408-411
Author(s):  
Xiao Yong Li
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Corrosion Test ◽  
Laboratory Tests ◽  
Structural Integrity ◽  
Mechanical Performance ◽  
Rock Bolt ◽  
Before And After ◽  
The Impact ◽  
Strength And Ductility

Corrosion is a negative contributor on the structural integrity of rock bolt and leads to degradation of the mechanical properties of steel rock bolt. Exposure to chloride, seawater, salt and saltwater and deicing chemical environments influences rock bolt and weakens it. In order to evaluate the influence of corrosion and the size of the steel on the mechanical properties of rock bolt, an experimental investigation was conducted on rock bolt whose rebar is 8, 12, 16, and 18 mm diameter, and which were artificially corroded for 10, 20, 30, 45, 60, 90, and 120 days. By the simulation corrosion test of loaded and unloaded bolts in Na2SO4 solution, the relation curves of the mechanical performance with the corrosive conditions and the corrosion time are given. The mechanical performance is compared between these two types of bolts. At the same time, the influential trend of the load on the mechanical performance of the corroded bolt is analyzed. The laboratory tests suggest that corrosion duration and rebar size had a significant impact on the strength and ductility degradation of the specimens. after being corroded in Na2SO4 solution, both the ultimate bearing capacity and the maximal tensility of loaded bolt decrease far more than those of unloaded bolt, and the endurance and service life of loaded bolt will also be shortened much more severely. The tensile mechanical properties before and after corrosion indicated progressive variation and drastic drop in their values.

scholarly journals Mechanical Performance and Microstructural Evolution of (NiCo)75Cr17Fe8Cx (x = 0~0.83) Medium Entropy Alloys at Room and Cryogenic Temperatures

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1646 ◽  
Author(s):  
Jae Sook Song ◽  
Byung Ju Lee ◽  
Won Jin Moon ◽  
Sun Ig Hong
Keyword(s):  
Cryogenic Temperature ◽  
Mechanical Performance ◽  
Friction Stress ◽  
Dislocation Slip ◽  
Alloy 600 ◽  
High Entropy ◽  
Carbon Doped ◽  
Carbide Strengthening ◽  
Strain Hardening Rate ◽  
Strength And Ductility

We investigated the effects of the addition of Co and carbon on the deformation behavior of new medium-entropy alloys (MEAs) designed by increasing the entropy of the conventional NiCrFe-type Alloy 600. The strength/ductility combination of carbon-free (NiCo)75Cr17Fe8 MEA was found to be 729 MPa/81% at 298 K and it increased to a remarkable 1212 MPa/106% at 77 K. The excellent strength and ductility of (NiCo)75Cr17Fe8 at cryogenic temperature is attributed to the increased strain hardening rate caused by the interaction between dislocation slip and deformation twins. Strength/ductility combinations of carbon-doped (NiCo)75Cr17Fe8C0.34 and (NiCo)75Cr17Fe8C0.83 at cryogenic temperature were observed to be 1321 MPa/96% and 1398 MPa/66%, respectively, both of which are superior to those of other high-entropy alloys (HEAs). Strength/ductility combinations of (NiCo)75Cr17Fe8C0.34 and (NiCo)75Cr17Fe8C0.83 at room temperature were found to be 831 MPa/72% and 942 MPa/55%, respectively and both are far superior to 676 MPa/41% of the commercial Alloy 600. Yield strengths of carbon-free and carbon-doped alloys comprised strengthening components from the friction stress, grain size strengthening, carbide strengthening and interstitial strengthening and excellent agreement between the predictions and the experiments was obtained. A design strategy to develop new MEAs by increasing the entropy of the conventional alloys was found to be effective in enhancing the mechanical performance.

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