Distribution control and formation mechanism of gas inclusions in directionally solidified Al2O3-Er3Al5O12-ZrO2 ternary eutectic ceramic by laser floating zone melting

2021 ◽  
Vol 66 ◽  
pp. 21-27
Author(s):  
Haijun Su ◽  
Yuan Liu ◽  
Qun Ren ◽  
Zhonglin Shen ◽  
Haifang Liu ◽  
...  
Keyword(s):  
Formation Mechanism ◽  
Ternary Eutectic ◽  
Zone Melting ◽  
Floating Zone ◽  
Directionally Solidified

Unidirectional Solidification of a Nbss/Nb5Si3 In-Situ Composite

2005 ◽  
Vol 475-479 ◽  
pp. 745-748 ◽  
Author(s):  
X.P. Guo ◽  
Ping Guan ◽  
X. Ding ◽  
Jun Zhang ◽  
K. Kusabiraki ◽  
...  
Keyword(s):  
Room Temperature ◽  
Melting Furnace ◽  
Longitudinal Axis ◽  
Zone Melting ◽  
Tensile Fracture ◽  
Al Alloy ◽  
Floating Zone ◽  
Directionally Solidified ◽  
In Situ Composite

The directionally solidified specimens of Nb-13.52 Si-22.60 Ti–6.88 Hf–2.54 Cr–2.24 Al alloy were prepared in an electron beam floating zone melting furnace at the withdrawing rate of 0.1, 0.3, 0.6, 1.0, 2.4 and 6.0 mm/min. All the primary Nb solid solution (Nbss) columns, Nbss + (Nb)3Si/(Nb)5Si3 eutectic colonies and divorced (Nb)3Si/(Nb)5Si3 plates or chains align well along the longitudinal axis of the specimens. With increasing of the withdrawing rate, the microstructure is gradually refined, and the amount of Nbss + (Nb)3Si/(Nb)5Si3 eutectic colonies increases. Both the room temperature ultimate tensile strength σb and fracture toughness KQ are improved for the directionally solidified specimens. The tensile fracture occurs in a cleavage way.

scholarly journals Effects of Solidification Conditions on Grain Refinement Capacity of TiC in Directionally Solidified Ti6Al4V Alloy

2021 ◽  
Author(s):  
Naoki Date ◽  
Shunya Yamamoto ◽  
Yoshimi Watanabe ◽  
Hisashi Sato ◽  
Shizuka Nakano ◽  
...  
Keyword(s):  
Grain Refinement ◽  
Solidification Rate ◽  
Field Method ◽  
Zone Melting ◽  
Ti6al4v Alloy ◽  
Phase Field Method ◽  
Floating Zone ◽  
Directionally Solidified ◽  
Constitutional Undercooling ◽  
Powder Bed

AbstractIn this study, the effects of solidification conditions on the grain refinement capacity of heterogeneous nuclei TiC in directionally solidified Ti6Al4V alloy were investigated using experimental and numerical approaches. Ti6Al4V powder with and without TiC particles in a Ti6Al4V sheath was melted and directionally solidified at various solidification rates via the floating zone melting method. In addition, by using the phase field method, the microstructural evolution of directionally solidified Ti6Al4V was simulated by varying the temperature gradient G and solidification rate V. As the solidification rate increased, the increment of the prior β grain number by TiC addition also increased. There are two reasons for this: first, the amount of residual potent heterogeneous nuclei TiC is larger. Second, the amount of TiC particles that can nucleate becomes larger. This is because increasing the constitutional undercooling ΔTc leads to the activation of a smaller radius of heterogeneous nuclei and a higher nucleation probability from each radius. At a cooling rate R higher than that in the floating zone melting experiment (R = 3 to 1000 K/s), the maximum degree of constitutional undercooling ΔTc,Max has a peak value, which suggests that constitutional undercooling ΔTc has a smaller contribution at higher cooling rates, such as those that occur during electron beam melting (EBM), including laser powder bed fusion (LPBF).

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.

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