Microstructure Evolution of a Directionally Solidified Ternary Eutectic Mo-Si-B Alloy

2016 ◽  
Vol 879 ◽  
pp. 1226-1232 ◽  
Author(s):  
Manja Krüger ◽  
Georg Hasemann ◽  
Omid Kazemi ◽  
Thorsten Halle
Keyword(s):  
High Temperature ◽  
Field Model ◽  
Ternary Eutectic ◽  
Phase Field Model ◽  
Eutectic Point ◽  
Zone Melting ◽  
Eutectic Phase ◽  
Nominal Composition ◽  
Directionally Solidified ◽  
Isotropic Model

The aim of the present study is to identify the ternary eutectic Mo-Si-B composition to produce directionally solidified materials, which are expected to have excellent high-temperature properties due to the well-defined microstructure. Different alloy compositions in the respective primary solidification areas of the phases were chosen to investigate the microstructural evolution. The results were compared to thermodynamic calculations of the liquidus projection and isopleth phase diagrams using the software FactSageTM. By carrying out these experiments the eutectic point was found to have a nominal composition of Mo-17.5Si-8B (at.%). In the next step, the eutectic alloy was directionally solidified by a zone melting (ZM) process. The evolution of a typical eutectic microstructure due to the growth of lamella-like structures is shown by microstructural investigations. Furthermore, we present a eutectic phase field model for the eutectic Mo-Si-B alloy. The equilibrium interface geometries and interface mobility were calculated using an isotropic model. The results are shown to be in an adequate conformity with the experimental observations.

Directionally Solidified Ceramic Eutectics for High-Temperature Applications

2013 ◽  
pp. 303-322 ◽  
Author(s):  
Iurii Bogomol ◽  
Petro Loboda
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Eutectic Point ◽  
Eutectic Microstructure ◽  
Directionally Solidified ◽  
Microstructure Parameters ◽  
Directionally Solidified Eutectics ◽  
Temperature Applications

The processing techniques, microstructures, and mechanical properties of directionally solidified eutectic ceramics are reviewed. It is considered the main methods for preparing of eutectic ceramics and the relationships between thermal gradient, growth rate, and microstructure parameters. Some principles of coupled eutectic growth, main types of eutectic microstructure and the relationship between the eutectic microstructure and the mechanical properties of directionally solidified eutectics at ambient and high temperatures are briefly described. The mechanical behavior and main toughening mechanisms of these materials in a wide temperature range are discussed. It is shown that the strength at high temperatures mainly depends on the plasticity of the phase components. By analyzing the dislocation structure, the occurrence of strain hardening in single crystalline phases during high-temperature deformation is revealed. The creep resistance of eutectic composites is superior to that of the sintered samples due to the absence of glassy phases at the interfaces, and the strain has to be accommodated by plastic deformation within the domains rather than by interfacial sliding. The microstructural and chemical stability of the directionally solidified eutectic ceramics at high temperatures are discussed. The aligned eutectic microstructures show limited phase coarsening up to the eutectic point and excellent chemical resistance. Directionally solidified eutectics, especially oxides, revealed an excellent oxidation resistance at elevated temperatures. It is shown sufficient potential of these materials for high-temperature applications.

scholarly journals Selection of Dedicated As-Cast Microstructures in Zn-Al-Cu Alloys for Bearing Applications Supported by Phase-Field Simulations

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1659
Author(s):  
Steffen Gimmler ◽  
Markus Apel ◽  
Andreas Bührig-Polaczek
Keyword(s):  
Phase Field ◽  
Ternary Eutectic ◽  
Phase Field Model ◽  
Eutectic Point ◽  
Casting Process ◽  
Primary Phase ◽  
Spatially Resolved ◽  
Cu Alloys ◽  
Mold Casting ◽  
Ε Phase

Solidification and phase formation of Zn-rich Zn-Al-Cu alloys with different Al and Cu contents were investigated. The investigations comprise alloy compositions with either hcp η, fcc α or hcp ε as the primary phase, as well as a composition close to the ternary eutectic point. Test samples were produced in a mold casting process and their microstructures were investigated by scanning electron microscopy. Experimental microstructures are compared with the results from spatially resolved microstructure simulations using a phase-field model. In particular, the dependency between the aluminum and copper contents and the phase fractions of the η, α and ε phases were analyzed. In addition, hardness tests for the samples prove a direct correlation between the α- and ε-phase fractions with the macroscopic hardness of the alloys. A simple model, based on the phase fractions and the properties of the single phases, is suggested for the computation of hardness from the simulation results in order to select appropriate alloy compositions for bearing applications.

scholarly journals Application of Phase-field Model to High Temperature Processing.

Materia Japan ◽  
1998 ◽  
Vol 37 (3) ◽  
pp. 184-188 ◽  
Author(s):  
Toshio Suzuki ◽  
Seong Gyoon Kim
Keyword(s):  
High Temperature ◽  
Phase Field ◽  
Field Model ◽  
Phase Field Model ◽  
High Temperature Processing

High Temperature Mechanical Behavior of MgAl2O4-YAG Eutectic Ceramic In Situ Composites by Float Zone Method

2017 ◽  
Vol 36 (8) ◽  
pp. 755-761 ◽  
Author(s):  
Serkan Abalı
Keyword(s):  
High Temperature ◽  
Young Modulus ◽  
Zone Melting ◽  
Directionally Solidified ◽  
Zone Method ◽  
Nitrogen Gas ◽  
Float Zone ◽  
Minimum Stress ◽  
High Frequency Induction

AbstractThe directionally solidified eutectic MgAl2O4-Y3Al5O12 crystal was prepared at a pressure of 0.4 MPa of ambient nitrogen gas by the high frequency induction heated floating zone furnace. In order to determine the high temperature characteristics, directionally solidified MgAl2O4-Y3Al5O12 eutectic phase has been analyzed with creep test, tensile strength, young modulus and fracture toughness at the various temperatures and the microstructural variations have been studied according to the analysis results. It has been seen that directionally solidified with zone melting MgAl2O4-YAG eutectic ceramic which has given the value of 168 MPa below 10−6/s strain rate at 1,700 °C temperature has revealed minimum stress.

scholarly journals Phase-Field Model of Electrothermal Breakdown in Flexible High-Temperature Nanocomposites under Extreme Conditions

2018 ◽  
Vol 8 (20) ◽  
pp. 1800509 ◽  
Author(s):  
Zhong-Hui Shen ◽  
Jian-Jun Wang ◽  
Jian-Yong Jiang ◽  
Yuan-Hua Lin ◽  
Ce-Wen Nan ◽  
...  
Keyword(s):  
High Temperature ◽  
Phase Field ◽  
Field Model ◽  
Phase Field Model ◽  
Extreme Conditions ◽  
Electrothermal Breakdown
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