Strengthening of a CoCrFeNiMn-Type High Entropy Alloy by Regular Arrays of Nanoprecipitates

2018 ◽  
Vol 941 ◽  
pp. 772-777 ◽  
Author(s):  
Nikita Stepanov ◽  
Dmitry Shaysultanov ◽  
Margarita Klimova ◽  
Vladimir Sanin ◽  
Sergey Zherebtsov
Keyword(s):  
Cold Rolling ◽  
Coarse Grained ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Single Face ◽  
Cold Rolling And Annealing ◽  
M23c6 Type ◽  
Face Centered ◽  
Fcc Phase

In this paper, we report microstructure and mechanical properties evolution of the CoCrFeNiMn-type high entropy alloy, containing small amounts of Al and C, during cold rolling and subsequent annealing at 700-1100°C. In the initial as-cast condition the alloy has coarse-grained single face-centered cubic (fcc) phase structure. Cold rolling and annealing substantially refine fcc grains; in addition M23C6 type carbides appear. After annealing at relatively low temperatures (≤900°C), these particles are arranged in characteristic arrays aligned with rolling directions. The specific microstructure of the thermomechanically processed alloy is suggested to be the reason of the balanced combination of tensile strength and ductility.

scholarly journals Effect of Mn Addition on the Microstructures and Mechanical Properties of CoCrFeNiPd High Entropy Alloy

Entropy ◽  
2019 ◽  
Vol 21 (3) ◽  
pp. 288
Author(s):  
Yiming Tan ◽  
Jinshan Li ◽  
Jun Wang ◽  
Hongchao Kou
Keyword(s):  
Intermetallic Compound ◽  
Interface Energy ◽  
High Entropy Alloy ◽  
Strengthening Effect ◽  
Face Centered Cubic ◽  
Liquid Interfaces ◽  
High Entropy ◽  
Single Face ◽  
Face Centered ◽  
Fcc Phase

CoCrFeNiPdMnx (x = 0, 0.2, 0.4, 0.6, 0.8) high entropy alloys (HEAs) were prepared and characterized. With an increase in Mn addition, the microstructures changed from dendrites (CoCrFeNiPd with a single face-centered-cubic (FCC) phase) to divorced eutectics (CoCrFeNiPdMn0.2 and CoCrFeNiPdMn0.4), to hypoeutectic microstructures (CoCrFeNiPdMn0.6), and finally to seaweed eutectic dendrites (CoCrFeNiPdMn0.8). The addition of Mn might change the interface energy anisotropy of both the FCC/liquid and MnPd-rich intermetallic compound/liquid interfaces, thus forming the seaweed eutectic dendrites. The hardness of the FCC phase was found to be highly related to the solute strengthening effect, the formation of nanotwins and the transition from CoCrFeNiPd-rich to CoCrFeNi-rich FCC phase. Hierarchical nanotwins were found in the MnPd-rich intermetallic compound and a decrease in either the spacing of primary twins or secondary twins led to an increase in hardness. The designing rules of EHEAs were discussed and the pseudo binary method was revised accordingly.

scholarly journals A high-entropy alloy with hierarchical nanoprecipitates and ultrahigh strength

2018 ◽  
Vol 4 (10) ◽  
pp. eaat8712 ◽  
Author(s):  
Zhiqiang Fu ◽  
Lin Jiang ◽  
Jenna L. Wardini ◽  
Benjamin E. MacDonald ◽  
Haiming Wen ◽  
...  
Keyword(s):  
Room Temperature ◽  
Failure Strain ◽  
Tensile Yield Strength ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
Metallic Materials ◽  
Strengthening Mechanisms ◽  
High Entropy ◽  
Face Centered ◽  
Fcc Phase

High-entropy alloys (HEAs) are a class of metallic materials that have revolutionized alloy design. They are known for their high compressive strengths, often greater than 1 GPa; however, the tensile strengths of most reported HEAs are limited. Here, we report a strategy for the design and fabrication of HEAs that can achieve ultrahigh tensile strengths. The proposed strategy involves the introduction of a high density of hierarchical intragranular nanoprecipitates. To establish the validity of this strategy, we designed and fabricated a bulk Fe25Co25Ni25Al10Ti15 HEA to consist of a principal face-centered cubic (fcc) phase containing hierarchical intragranular nanoprecipitates. Our results show that precipitation strengthening, as one of the main strengthening mechanisms, contributes to a tensile yield strength (σ0.2) of ~1.86 GPa and an ultimate tensile strength of ~2.52 GPa at room temperature, which heretofore represents the highest strength reported for an HEA with an appreciable failure strain of ~5.2%.

scholarly journals Nitrogen Interstitial Alloying of CoCrFeMnNi High Entropy Alloy through Reactive Powder Milling

Entropy ◽  
2019 ◽  
Vol 21 (4) ◽  
pp. 363 ◽  
Author(s):  
Igor Moravcik ◽  
Jan Cizek ◽  
Larissa Gouvea ◽  
Jan Cupera ◽  
Ivan Guban ◽  
...  
Keyword(s):  
Lattice Parameter ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
Simple Method ◽  
High Entropy ◽  
Plasma Sintering ◽  
Milling Duration ◽  
Face Centered ◽  
Fcc Phase ◽  
Reactive Powder

The present work is focused on the synthesis of CoCrFeMnNi high entropy alloy (HEA) interstitially alloyed with nitrogen via powder metallurgy routes. Using a simple method, nitrogen was introduced to the HEA from the protective N2 gas atmosphere during mechanical alloying (MA) processing. The lattice parameter and amount of nitrogen in HEA were observed to be linearly proportional to the milling duration. The limited solubility of nitrogen in the main face centered cubic (FCC) phase resulted in the in-situ formation of nitrides and, accordingly, significant increase in the hardness values. It has been shown that fabrication of such nitrogen-doped HEA bulk materials can be conveniently achieved by a simple combination of MA + spark plasma sintering processes, without the need for adding nitrogen from other sources.

Laser cladding of FeCoCrNi high-entropy alloy on Ti-6Al-4V alloy: Microstructure, phase transformation and bonding region

2020 ◽  
pp. 2150037
Author(s):  
Xiaohong Zhan ◽  
Chaoqi Qi ◽  
Mengyao Wu ◽  
Lijun Liu ◽  
Zhuanni Gao
Keyword(s):  
Laser Cladding ◽  
Element Distribution ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
Rich Phase ◽  
High Entropy ◽  
Comprehensive Properties ◽  
Input Material ◽  
Face Centered ◽  
Fcc Phase

High-entropy alloys (HEAs) have shown considerable promise from both a scientific and an application perspective due to their outstanding comprehensive properties. In this study, an equiatomic FeCoCrNi HEA is used as input material for laser cladding on Ti-6Al-4V alloy. The HEA coating is characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) to investigate the bonding region, element distribution and microstructure evolution. The results show that the HEA coating is mainly composed of face-centered cubic (FCC) phase and body-centered cubic (BCC) phase, precipitating a small amount of (Fe, Cr)-rich phase and (Ni, Ti)-rich phase. Otherwise, the bonding region, which is between coating and substrate, is emphatically concerned in this paper. The bonding region is formed by the convection zone which is resulted from the density difference of HEA and TC4. In addition, the convection in molten pool plays a key role in the morphology of bonding region.

scholarly journals Vacuum brazing of Al2O3 and 3D printed Ti6Al4V lap-joints using high entropy driven AlZnCuFeSi filler

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ashutosh Sharma ◽  
Byungmin Ahn
Keyword(s):  
Strength Properties ◽  
Lap Joints ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
3D Printed ◽  
Face Centered ◽  
Alloy Filler

AbstractIn this work, we studied the brazing characteristics of Al2O3 and 3D printed Ti–6Al–4V alloys using a novel equiatomic AlZnCuFeSi high entropy alloy filler (HEAF). The HEAF was prepared by mechanical alloying of the constituent powder and spark plasma sintering (SPS) approach. The filler microstructure, wettability and melting point were investigated. The mechanical and joint strength properties were also evaluated. The results showed that the developed AlZnCuFeSi HEAF consists of a dual phase (Cu–Zn, face-centered cubic (FCC)) and Al–Fe–Si rich (base centered cubic, BCC) phases. The phase structure of the (Cu–Al + Ti–Fe–Si)/solid solution promises a robust joint between Al2O3 and Ti–6Al–4V. In addition, the joint interfacial reaction was found to be modulated by the brazing temperature and time because of the altered activity of Ti and Zn. The optimum shear strength reached 84 MPa when the joint was brazed at 1050 °C for 60 s. The results can be promising for the integration of completely different materials using the entropy driven fillers developed in this study.

scholarly journals Microstructure Refinement by Low-Temperature Ausforming in an Fe-Based Metastable High-Entropy Alloy

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 742
Author(s):  
Motomichi Koyama ◽  
Takeaki Gondo ◽  
Kaneaki Tsuzaki
Keyword(s):  
Low Temperature ◽  
Plastic Anisotropy ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Microstructure Refinement ◽  
Hexagonal Close Packed ◽  
Solution Treated Condition ◽  
Solution Treated ◽  
Face Centered

The effects of ausforming in an Fe30Mn10Cr10Co high-entropy alloy on the microstructure, hardness, and plastic anisotropy were investigated. The alloy showed a dual-phase microstructure consisting of face-centered cubic (FCC) austenite and hexagonal close-packed (HCP) martensite in the as-solution-treated condition, and the finish temperature for the reverse transformation was below 200 °C. Therefore, low-temperature ausforming at 200 °C was achieved, which resulted in microstructure refinement and significantly increased the hardness. Furthermore, plasticity anisotropy, a common problem in HCP structures, was suppressed by the ausforming treatment. This, in turn, reduced the scatter of the hardness.

Enhanced strength and slightly reduced ductility in a high entropy alloy via cold rolling and annealing

2020 ◽  
Vol 817 ◽  
pp. 152709 ◽  
Author(s):  
Zhichao Ma ◽  
Wei Zhang ◽  
Hongwei Zhao ◽  
Fangzhou Lu ◽  
Zhihui Zhang ◽  
...  
Keyword(s):  
Cold Rolling ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Cold Rolling And Annealing

scholarly journals Cutting Edge of High-Entropy Alloy Superconductors from the Perspective of Materials Research

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1078
Author(s):  
Jiro Kitagawa ◽  
Shusuke Hamamoto ◽  
Naoki Ishizu
Keyword(s):  
Material Design ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
Simple Material ◽  
Σ Phase ◽  
High Entropy ◽  
Cscl Type ◽  
Materials Research ◽  
Face Centered ◽  
New Phenomena

High-entropy alloys (HEAs) are a new class of materials which are being energetically studied around the world. HEAs are characterized by a multicomponent alloy in which five or more elements randomly occupy a crystallographic site. The conventional HEA concept has developed into simple crystal structures such as face-centered-cubic (fcc), body-centered-cubic (bcc) and hexagonal-closed packing (hcp) structures. The highly atomic-disordered state produces many superior mechanical or thermal properties. Superconductivity has been one of the topics of focus in the field of HEAs since the discovery of the bcc HEA superconductor in 2014. A characteristic of superconductivity is robustness against atomic disorder or extremely high pressure. The materials research on HEA superconductors has just begun, and there are open possibilities for unexpectedly finding new phenomena. The present review updates the research status of HEA superconductors. We survey bcc and hcp HEA superconductors and discuss the simple material design. The concept of HEA is extended to materials possessing multiple crystallographic sites; thus, we also introduce multisite HEA superconductors with the CsCl-type, α-Mn-type, A15, NaCl-type, σ-phase and layered structures and discuss the materials research on multisite HEA superconductors. Finally, we present the new perspectives of eutectic HEA superconductors and gum metal HEA superconductors.

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