scholarly journals Microstructure and Shear Strength of Brazing High Entropy TiZrHfNbMo Alloy and Si3N4 Ceramics Joints

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 472
Author(s):  
Xiaohong Wang ◽  
Duo Dong ◽  
Xiaohong Yang ◽  
Peng Huang ◽  
Kangqiao Shi ◽  
...  
Keyword(s):  
Solid Solution ◽  
Shear Strength ◽  
Intermetallic Compounds ◽  
Reaction Layer ◽  
Interfacial Microstructure ◽  
High Entropy Alloy ◽  
Si3n4 Ceramic ◽  
High Entropy ◽  
Brazed Joints ◽  
Brazed Joint

The effects of different brazing processes on the interfacial microstructure and shear strength of TiZrHfNbMo high-entropy alloy (HEAS) and Si3N4 ceramic brazed joints were studied. There is no obvious defect in a brazed TiZrHfNbMo HEAS/AgCuTi/Si3N4 ceramic joint, and the two materials have good metallurgical bonding. The typical interface microstructure is Si3N4/Ti5Si3/Ag solid solution +Cu (s,s)+ CuTi/Cu2Ti/Cu4Ti + TiCu(Hf,Zr)NbMo/TiZrHfNbMo HEAs. With the increase of brazing temperature, the dispersed CuTi phase agglomerates in the brazed joint, and acts as the nucleate of the Cu-based solid solution. The thickness of the reaction layer increases with the increase of phases in the reaction layer on both sides of the joint. When the brazing temperature is 800 °C, 820 °C, 840 °C and 860 °C, the shear strength of the brazed joint is 30 MPa, 72 MPa, 86 MPa and 21 MPa, respectively. The formation of CuTi and Ti5Si3 intermetallic compounds increases the thickness of the reaction layer, and improves the strength of the joint. However, excessive CuTi and Ti5Si3 intermetallic compounds lead to a significant decrease in joint strength. The grain coarsening of the joint can also affect the strength of the joint.

Solid State Amorphization and Alloy Parameters for High Entropy Alloys

2021 ◽  
Vol 1016 ◽  
pp. 990-996
Author(s):  
Takeshi Nagase
Keyword(s):  
Solid Solution ◽  
Solid State ◽  
Intermetallic Compounds ◽  
Electron Irradiation ◽  
Fast Electron ◽  
High Entropy Alloy ◽  
Solid Solution Formation ◽  
High Entropy ◽  
Solution Formation ◽  
State Amorphization

Fast electron irradiation can induce the solid-state amorphization (SSA) of many intermetallic compounds. The occurrence of SSA stimulated by fast electron irradiation was found in the Al0.5TiZrPdCuNi high-entropy alloy (HEA). The relationship between the occurrence of SSA in intermetallic compounds under fast electron irradiation and the empirical alloy parameters for predicting the solid-solution-formation tendency in HEAs was discussed. The occurrence of SSA in intermetallic compounds was hardly predicted, only by the alloy parameters of δ or ΔHmix, which have been widely used for predicting solid-solution formation in HEAs. All intermetallic compounds with ΔHmix ≤ -35 kJ/mol and those with δ ≥ 12.5 exhibit the occurrence of SSA. This implies that the intermetallic compounds with a largely negative ΔHmix value and a largely positive δ parameter are favorable for the occurrence of SSA.

scholarly journals Infrared Brazing of CoCrFeMnNi Equiatomic High Entropy Alloy Using Nickel-Based Braze Alloys

Entropy ◽  
2019 ◽  
Vol 21 (3) ◽  
pp. 283 ◽  
Author(s):  
Chieh Lin ◽  
Ren-Kae Shiue ◽  
Shyi-Kaan Wu ◽  
Huai-Li Huang
Keyword(s):  
Shear Strength ◽  
Grain Boundary ◽  
High Entropy Alloy ◽  
Solidification Shrinkage ◽  
Vacuum Brazing ◽  
High Entropy ◽  
Average Shear Strength ◽  
Average Shear ◽  
Brazed Joints ◽  
Liquidus Temperatures

Infrared vacuum brazing of CoCrFeMnNi high entropy alloy (HEA) using BNi-2 and MBF601 fillers has been investigated. Both brazes show poor wettability at temperatures only 20 °C above their liquidus temperatures. However, the wettability of BNi-2 and MBF601 fillers on CoCrFeMnNi HEA is greatly improved with increasing the test temperatures, 50 °C above their liquidus temperatures. The BNi-2 brazed joints are dominated by Ni-rich matrix with huge CrB and a few tiny boride precipitates. Average shear strengths of joints increase with increasing brazing temperature and/or time, and fracture location changes from blocky CrB in the brazed zone to grain boundary boride in the substrate. The MBF601 brazed joints are composed of CoCrFeMnNi-based matrix, particles of B/Co/Cr/Fe/Mn/Ni/P compounds, and some phosphides form along the grain boundaries of the substrate. The specimen brazed with MBF601 filler foil at 1050 °C for 600 s has the highest average shear strength of 321 MPa, while that brazed at 1080 °C for 600 s has a lower average shear strength of 271 MPa due to the presence of solidification shrinkage voids.

Brazing of Porous Copper Foam with Copper Sheet Using CuNiSnP Amorphous Filler Metal

2021 ◽  
Vol 904 ◽  
pp. 382-386
Author(s):  
Niwat Mookam ◽  
Prajak Jattakul ◽  
Tipsuda Rakphet ◽  
Kannachai Kanlayasiri
Keyword(s):  
Solid Solution ◽  
Electric Furnace ◽  
Filler Metal ◽  
Eutectic Structure ◽  
Interfacial Microstructure ◽  
Copper Sheet ◽  
Copper Foam ◽  
Porous Copper ◽  
Brazed Joints ◽  
Brazed Joint

This research studies effects of the brazing time on interfacial microstructure of brazed joint between the porous copper foam (PCF) and Cu substrate using CuNiSnP amorphous filler metal. To examine the interfacial microstructure and its properties, an assessment of PCF/CuNiSnP/Cu brazed joints was conducted after electric furnace brazing under hydrogen (H2) atmosphere. The results showed that the interfacial microstructure was thick for short brazing time specimens and thin for prolonged brazing time specimens. The interfacial microstructures consisted of Cu-rich solid solution, (Cu, Ni)3P, and Cu3P as a eutectic structure discovered in the brazing region at different brazing times of 5, 10, and 20 min. Only the Cu-rich solid solution and (Cu, Ni)3P were found in the specimen with brazing time of 30 min. indicating that different brazing times affected interfacial microstructures and therefore reliability of the brazed joints.

Brazing of transparent polycrystalline Al2O3 and GH99 with the assistance of (Cu, Ni) solid solution cladding layer

2020 ◽  
Author(s):  
Bo Zhang ◽  
Lixia Zhang ◽  
Zhan Sun ◽  
Jicai Feng
Keyword(s):  
Solid Solution ◽  
Shear Strength ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Joint Shear Strength ◽  
Brazed Joints ◽  
Brazed Joint ◽  
Solution Layer ◽  
Cu Foil ◽  
Pure Cu

Abstract In this study, pure Cu foil was firstly vacuum cladding on the GH99 alloy (GH99) surface to prepare a (Cu, Ni) solid solution layer. By varying the cladding temperatures, (Cu, Ni) solid solution layers with different Ni contents were achieved. The vacuum cladding process was then followed by vacuum brazing of the Cu-coated GH99 to transparent polycrystalline Al 2 O 3 (TPA). Typical microstructure of the TPA/Cu-cladding GH99 brazed joint was characterized. The effects of different cladding temperatures on microstructural evolution and mechanical response of the brazed joints were discussed. By varying the cladding temperature, different thickness of the reaction layer at the braze filler/TPA interfaces can be achieved, which shows a strong correlation with the mechanical performance of the brazed joint. The maximum shear strength of the brazed joint reached 103 MPa when the cladding temperature was 1105 ºC. Compared with the directly brazed joint, shear strength was improved by 472%.

scholarly journals Brazing Si3N4 Ceramic to Molybdenum Using an Ag-Cu-Ti Filler

2021 ◽  
Vol 100 (6) ◽  
pp. 206-212
Author(s):  
TONG ZHAO ◽  
◽  
DE FENG MO ◽  
LI QUAN YU ◽  
YU YU WANG ◽  
...  
Keyword(s):  
Reaction Layer ◽  
Energy Dispersive Spectrometer ◽  
Base Material ◽  
Interfacial Microstructure ◽  
X Ray Diffraction ◽  
Si3n4 Ceramic ◽  
Typical Structure ◽  
X Ray ◽  
Brazed Joint ◽  
Continuous Reaction

A Si3N4 ceramic was successfully joined to molybdenum(Mo) using an Ag-Cu-Ti filler alloy. The interfacial microstructure of the Si3N4/Ag-Cu-Ti/Mo joint was investigated by scanning an electron microscopy, energy dispersive spectrometer, and x-ray diffraction. The results showed the joint brazed at 900˚C for 10 min was smooth, and there were no holes and cracks at the interface. A continuous reaction layer, which is composed of TiN and TiSi2, was formed near the Si3N4 ceramic, with TiN being located near the ceramic. The central part of the joint was composed of Ag- and Cu-based solid solutions. At the side near the Mo metal, there was a formation of the MoTi solid solution. The typical structure of the Si3N4/Mo joint was Si3N4/TiN  TiSi2 reaction layer/Ag(s,s) Cu(s,s)/MoTi/Mo. Because TiN and TiSi2 com-pounds are generated on the ceramic side, the microhardness of the reaction layer on the ceramic side was de-creased but still much higher than the hardness of the brazing seam and the Mo base material. The shear strength of the brazed joint was 204 MPa at room temperature.

scholarly journals The Evolution of Intermetallic Compounds in High-Entropy Alloys: From the Secondary Phase to the Main Phase

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2054
Author(s):  
Junqi Liu ◽  
Xiaopeng Wang ◽  
Ajit Singh ◽  
Hui Xu ◽  
Fantao Kong ◽  
...  
Keyword(s):  
Solid Solution ◽  
Intermetallic Compound ◽  
Intermetallic Compounds ◽  
High Performance ◽  
Single Phase ◽  
Secondary Phase ◽  
Main Phase ◽  
High Entropy Alloy ◽  
High Entropy Alloys ◽  
High Entropy

High-performance structural materials are critical to the development of transportation, energy, and aerospace. In recent years, newly developed high-entropy alloys with a single-phase solid-solution structure have attracted wide attention from researchers due to their excellent properties. However, this new material also has inevitable shortcomings, such as brittleness at ambient temperature and thermodynamic instability at high temperature. Efforts have been made to introduce a small number of intermetallic compounds into single-phase solid-solution high-entropy alloys as a secondary phase to their enhance properties. Various studies have suggested that the performance of high-entropy alloys can be improved by introducing more intermetallic compounds. At that point, researchers designed an intermetallic compound-strengthened high-entropy alloy, which introduced a massive intermetallic compound as a coherent strengthening phase to further strengthen the matrix of the high-entropy alloy. Inspired from this, Fantao obtained a new alloy—high-entropy intermetallics—by introducing different alloying elements to multi-principalize the material in a previous study. This new alloy treats the intermetallic compound as the main phase and has advantages of both structural and functional materials. It is expected to become a new generation of high-performance amphibious high-entropy materials across the field of structure and function. In this review, we first demonstrate the inevitability of intermetallic compounds in high-entropy alloys and explain the importance of intermetallic compounds in improving the properties of high-entropy alloys. Secondly, we introduce two new high-entropy alloys mainly from the aspects of composition design, structure, underlying mechanism, and performance. Lastly, the high-entropy materials containing intermetallic compound phases are summarized, which lays a theoretical foundation for the development of new advanced materials.

scholarly journals Nanoporous Quasi-High-Entropy Alloy Microspheres

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 345 ◽  
Author(s):  
Lianzan Yang ◽  
Yongyan Li ◽  
Zhifeng Wang ◽  
Weimin Zhao ◽  
Chunling Qin
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Hierarchical Porous

High-entropy alloys (HEAs) present excellent mechanical properties. However, the exploitation of chemical properties of HEAs is far less than that of mechanical properties, which is mainly limited by the low specific surface area of HEAs synthesized by traditional methods. Thus, it is vital to develop new routes to fabricate HEAs with novel three-dimensional structures and a high specific surface area. Herein, we develop a facile approach to fabricate nanoporous noble metal quasi-HEA microspheres by melt-spinning and dealloying. The as-obtained nanoporous Cu30Au23Pt22Pd25 quasi-HEA microspheres present a hierarchical porous structure with a high specific surface area of 69.5 m2/g and a multiphase approximatively componential solid solution characteristic with a broad single-group face-centered cubic XRD pattern, which is different from the traditional single-phase or two-phase solid solution HEAs. To differentiate, these are named quasi-HEAs. The synthetic strategy proposed in this paper opens the door for the synthesis of porous quasi-HEAs related materials, and is expected to promote further applications of quasi-HEAs in various chemical fields.

A review on phase prediction in high entropy alloys

2021 ◽  
pp. 095440622110089
Author(s):  
Vinay Kumar Soni ◽  
S Sanyal ◽  
K Raja Rao ◽  
Sudip K Sinha
Keyword(s):  
Solid Solution ◽  
Phase Formation ◽  
Single Phase ◽  
High Entropy Alloy ◽  
High Entropy Alloys ◽  
Modeling Tools ◽  
High Entropy ◽  
Recent Developments ◽  
Phase Prediction ◽  
The Stability

The formation of single phase solid solution in High Entropy Alloys (HEAs) is essential for the properties of the alloys therefore, numerous approach were proposed by many researchers to predict the stability of single phase solid solution in High Entropy Alloy. The present review examines some of the recent developments while using computational intelligence techniques such as parametric approach, CALPHAD, Machine Learning etc. for prediction of various phase formation in multicomponent high entropy alloys. A detail study of this data-driven approaches pertaining to the understanding of structural and phase formation behaviour of a new class of compositionally complex alloys is done in the present investigation. The advantages and drawbacks of the various computational are also discussed. Finally, this review aims at understanding several computational modeling tools complying the thermodynamic criteria for phase formation of novel HEAs which could possibly deliver superior mechanical properties keeping an aim at advanced engineering applications.

Vacuum Brazing Incoloy 800 Using the Copper Foil

2015 ◽  
Vol 1101 ◽  
pp. 99-103
Author(s):  
Cheng Yen Wang ◽  
Ren Kae Shiue
Keyword(s):  
Shear Strength ◽  
Copper Foil ◽  
Vacuum Furnace ◽  
Vacuum Brazing ◽  
Average Shear Strength ◽  
Average Shear ◽  
Incoloy 800 ◽  
Brazed Joints ◽  
Brazed Joint ◽  
Time Average

The purpose of this research is focused on vacuum furnace brazing Incoloy 800 (IN-800) using the copper filler foil. Microstructural evolution and shear strength of brazed joints for various brazing conditions has been evaluated in the experiment. The Cu-rich matrix dominates entire brazed joint. The width of Cu-rich matrix is decreased with increasing the brazing temperature and/or time. Average shear strength of the joint is approximately 215 MPa. Dimple dominated fracture is widely observed for the specimen brazed below 1160oC. However, cleavage dominated fracture is found for the specimen brazed at 1200oC. It is advised that copper brazing IN-800 alloy should be confined below 1160oC.

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