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 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 Laser Cladding of Al0.5CoCrCuFeNiSi High Entropy Alloy Coating without and with Yttria Addition on H13 Steel

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 320
Author(s):  
Jingda Liu ◽  
Yuxin Guan ◽  
Xuechen Xia ◽  
Pai Peng ◽  
Qifeng Ding ◽  
...  
Keyword(s):  
Laser Cladding ◽  
Atomic Radius ◽  
Alloy Coating ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
H13 Steel ◽  
High Entropy ◽  
Face Centered ◽  
Y2o3 Addition

Al0.5CoCrCuFeNiSi high entropy alloy coating without and with a 1 wt.% Y2O3 addition was fabricated by laser cladding technique on H13 substrate. The results showed that the laser cladding coatings without and with Y2O3 addition consist of a mixture of body centered cubic (BCC) dendrites and face centered cubic (FCC) interdendrites. With the addition of Y2O3, the peaks of BCC dendrites in the coating shifted to leftwards, which is caused by the distortion of lattice due to the dissolution of Y with larger atomic radius. There exist cracks and porosities in the coating without Y2O3 addition. With Y2O3 addition, the cracks and porosities in the laser cladding coating were inhibited greatly. In addition, the microstructure of the coating with Y2O3 addition was refined due to the improving of the ratio of nucleation. The enhancement of properties, such as hardness, wear resistance and corrosion resistance, of the coating with Y2O3 addition came from the inhibition of cracks and porosities and the refinement of microstructure.

scholarly journals Phase Evolution, Microstructure and Mechanical Property of AlCoCrFeNiTi High-Entropy Alloy Coatings Prepared by Mechanical Alloying and Laser Cladding

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1036
Author(s):  
Weijie Yu ◽  
Yun Wang ◽  
Ruitao Li ◽  
Junhong Mao
Keyword(s):  
Mechanical Alloying ◽  
Laser Cladding ◽  
Steel Substrate ◽  
Phase Evolution ◽  
High Entropy Alloy ◽  
Second Phase ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Fcc Phase ◽  
Bcc Phase

AlCoCrFeNiTi high-entropy alloy coatings (HEACs) were prepared by mechanical alloying (MA) and laser cladding (LC) process on H13 hot-working die steel substrate. Phase evolution, microstructure, and mechanical properties of the alloyed powder and HEACs were investigated in detail. The final milling AlCoCrFeNiTi coating powders exhibited simple body centered cubic (BCC) phase and mean granular size of less than 4 μm. With the increase of heat input of the laser, partial BCC phase transformed into minor face centered cubic (FCC) phase during LC. AlCoCrFeNiTi HEACs showed excellent metallurgical bonding with the substrate, and few defects. Moreover, the microhardness of AlCoCrFeNiTi HEACs reached 1069 HV due to the existence of the hard oxidation and the second phase grains, which are about five times that of the substrate. The laser surface cladding HEACs exhibited deteriorated tensile property compared with that of the substrate and the fracture generally occurred in the region of HEACs. The fracture mechanism of AlCoCrFeNiTi HEACs was dominated by the comprehensive influence of brittle fracture and ductile fracture.

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 Effect of Ti Content on the Microstructure and Corrosion Resistance of CoCrFeNiTix High Entropy Alloys Prepared by Laser Cladding

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2209 ◽  
Author(s):  
Xinyang Wang ◽  
Qian Liu ◽  
Yanbin Huang ◽  
Lu Xie ◽  
Quan Xu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Laser Cladding ◽  
First Principles ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
First Principles Calculations ◽  
High Entropy ◽  
Niti Phase ◽  
Fcc Phase ◽  
Ti Content

In this paper, CoCrFeNiTix high entropy alloy (HEA) coatings were prepared on the surface of Q235 steel by laser cladding. The microstructure, microhardness, and corrosion resistance of the coatings were studied. The mechanism of their corrosion resistance was elucidated experimentally and by first-principles calculations. The results show that CoCrFeNiTi0.1 adopts a face-centered cubic (FCC) phase, CoCrFeNiTi0.3 exhibits an FCC phase and a tetragonal FeCr phase, and CoCrFeNiTi0.5 adopts an FCC phase, a tetragonal FeCr phase, and a rhombohedral NiTi phase. The FCC phase, tetragonal FeCr phase, rhombohedral NiTi phase, and hexagonal CoTi phase are all observed in the CoCrFeNiTi0.7 HEA. The alloys assume the dendritic structure that is typical of HEAs. Ni and Ti are enriched in the interdendritic regions, whereas Cr and Fe are enriched in the dendrites. With increasing Ti content, the hardness of the cladding layers also increases due to the combined effects of lattice distortion and dispersion strengthening. When exposed to a 3.5 wt.% NaCl solution, pitting corrosion is the main form of corrosion on the CoCrFeNiTix HEA surfaces. The corrosion current densities of CoCrFeNiTix HEAs are much lower than those of other HEAs. As the Ti content increases, the corrosion resistance is improved. Through X-ray photoelectron spectroscopy (XPS) and first-principles calculations, the origin of the higher corrosion resistance of the coatings is connected to the presence of a dense passivation film. In summary, the corrosion resistance and mechanical properties of CoCrFeNiTi0.5 alloy are much better than the other three groups, which promotes the development of HEA systems with high value for industrial application.

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.

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 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.

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