Evaluation of primary dendrite trunk diameters in directionally solidified Al-Si alloys

1992 ◽  
Vol 28 (4) ◽  
pp. 213-219 ◽  
Author(s):  
R.N. Grugel
Keyword(s):  
Primary Dendrite ◽  
Directionally Solidified ◽  
Dendrite Trunk ◽  
Primary Dendrite Trunk

Primary dendrite array morphology in Al-7 wt% Si alloy samples directionally solidified aboard the International Space Station

2021 ◽  
Vol 562 ◽  
pp. 126077
Author(s):  
Masoud Ghods ◽  
Supriya R. Upadhyay ◽  
Ravi S. Rajamure ◽  
Surendra N. Tewari ◽  
Richard N. Grugel ◽  
...  
Keyword(s):  
International Space Station ◽  
Primary Dendrite ◽  
Space Station ◽  
Directionally Solidified ◽  
International Space

Growth Directions of Primary Phases in Directionally Solidified Ti-45Al-7Nb Alloys

2013 ◽  
Vol 32 (1) ◽  
pp. 69-75
Author(s):  
Jie Yan ◽  
Lijing Zheng ◽  
HuaRui Zhang ◽  
Zhixia Xiao ◽  
Hu Zhang
Keyword(s):  
Deflection Angle ◽  
Primary Dendrite ◽  
Growth Direction ◽  
Directionally Solidified ◽  
Electron Backscattered Diffraction ◽  
Lamellar Orientation ◽  
Primary Dendrite Arm Spacing ◽  
The Deflection Angle ◽  
Solidification Pathway ◽  
Liquid Metal Cooling

AbstractTi-45Al-7Nb alloys are produced by liquid-metal-cooling (LMC) directional solidification (DS) furnace with different temperature gradients (G) at a range of 40–80 K/cm. The growth directions of primary β phases and the deflection angles relative to the 〈100〉β direction were investigated. The solidification pathway of alloy is: Liq. → Liq. + β → β → β + α → α + γ → lamella (α2 + γ) + B2. Primary dendrite arm spacing λ reduced from 611.4 µm to 508.7 µm when G increased from 40 K cm−1 to 80 K cm−1. Grains with lamellar orientation aligned at the angles of 12–15° and 55° to growth direction were favored for various G. The orientations of the γ lamellas in steady-state regions were identified by the electron backscattered diffraction analysis (EBSD). The results indicated that the growth directions of primary bcc-β dendrites were 〈211〉β and 〈110〉β at 40 K/cm, 〈210〉β and 〈211〉β at 50 K/cm and 〈211〉β at 80 K/cm, the deflection angle of 〈211〉β relative to 〈100〉β direction is 35.3°.

Relationship between Growth Rates and Dendritic Microstructure Parameters in Al-5wt. Zn Binary Alloy

2013 ◽  
Vol 765 ◽  
pp. 215-219 ◽  
Author(s):  
Emine Acer ◽  
Harun Erol ◽  
Mehmet Gündüz
Keyword(s):  
Growth Rates ◽  
Numerical Models ◽  
Primary Dendrite ◽  
Linear Regression Analysis ◽  
Experimental Results ◽  
Directionally Solidified ◽  
Dendritic Microstructure ◽  
Dendrite Arm Spacing ◽  
Primary Dendrite Arm Spacing ◽  
Microstructure Parameters

Al-5 wt.% Zn samples were prepared using high purity (99.99%) metals in graphite crucibles. The samples were directionally solidified upward with a constant temperature gradient (G= 5.5 Kmm-1) and different growth rates,V, (8.25-165 μm/s) in a Bridgman type directional solidification apparatus. The dendritic spacings (λ1: Primary dendrite arm spacing, and λ2: Secondary dendrite arm spacing) were measured from the longitudinal sections of the samples and λ1was also measured from the transverse sections. The measured spacings were expressed as functions of the growth rates by using a linear regression analysis. The effect ofVon λ1and λ2were investigated. The experimental results were compared with the results of the current theoretical and numerical models and similar previous experimental results.

INFLUENCE OF THE SOLIDIFICATION PARAMETERS ON DENDRITIC MICROSTRUCTURES IN UNSTEADY-STATE DIRECTIONALLY SOLIDIFIED OF LEAD–ANTIMONY ALLOY

2010 ◽  
Vol 17 (05n06) ◽  
pp. 477-486 ◽  
Author(s):  
M. ŞAHIN ◽  
E. ÇADIRLI ◽  
H. KAYA
Keyword(s):  
Growth Rate ◽  
Primary Dendrite ◽  
Linear Regression Analysis ◽  
Theoretical Models ◽  
Directionally Solidified ◽  
Constant Growth Rate ◽  
Dendrite Arm Spacing ◽  
Primary Dendrite Arm Spacing ◽  
Microstructure Parameters ◽  
Solidification Parameters

Pb-9.3wt.%Sb alloy was directionally solidified upwards under argon atmosphere under the two conditions; with different temperature gradients, (G = 0.93–3.67 K/mm) at a constant growth rate (V = 17.50 μm/s) and with different growth rates (V = 8.30–497.00 μm/s) at a constant (G = 3.67 K/mm) in a Bridgman furnace. The dependence of characteristic microstructure parameters such as primary dendrite arm spacing (λ1), secondary dendrite arm spacing (λ2) and dendrite tip radius (R) on the growth rate (V) and the temperature gradient (G) were determined by using a linear regression analysis. A detailed analysis of microstructure were also made and compared with the theoretical models and similar experimental works on dendritic solidification in the literature.

scholarly journals Influence of Crystal Orientation on the Freckle Formation in Directionally Solidified Superalloys

2011 ◽  
Vol 278 ◽  
pp. 114-119 ◽  
Author(s):  
De Xin Ma ◽  
Michael Mathes ◽  
Bin Zhou ◽  
Andreas Bührig-Polaczek
Keyword(s):  
Crystal Orientation ◽  
Primary Dendrite ◽  
Flow Speed ◽  
Directionally Solidified ◽  
Directional Solidification Experiment ◽  
Dendrite Network ◽  
Freckle Formation ◽  
Shell Mould ◽  
Analogue System ◽  
Superalloy Castings

Freckle occurrence is known to be dependent on the casting size and the superalloy components with large cross section are more prone to freckle formation. In our directional solidification experiment of superalloys freckles are observed in some thin samples, while some significantly thicker samples in the same shell mould cluster remain freckle free. The EBSD analysis shows that the samples with freckles have a good <001> axial orientation, while in freckle free samples the primary dendrite stems diverge from the sample axis. In an analogue system the flow behaviour through a mushy zone was simulated, in which the dendrite network was placed in different orientation. The <001> dendrite array shows the lowest resistance to the vertical melt flow. As the dendrite alignment diverges from <001> orientation, the flow speed slows down and reaches the minimum at the <111> orientation. This orientation effect of the interdendritic permeability explains well why the crystal orientation plays such an important role in the occurrence of freckles in superalloy castings.

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