Effects of Growth Rates and Compositions on Dendrite Arm Spacings in Directionally Solidified Al-Zn Alloys

2017 ◽  
Vol 48 (12) ◽  
pp. 5911-5923 ◽  
Author(s):  
Emine Acer ◽  
Emin Çadırlı ◽  
Harun Erol ◽  
Hasan Kaya ◽  
Mehmet Gündüz
Keyword(s):  
Growth Rates ◽  
Directionally Solidified ◽  
Zn Alloys

scholarly journals Effect of Growth Velocity and Zn Content on Microhardness in Directionally Solidified Al-Zn Alloys

2018 ◽  
Vol 21 (6) ◽  
Author(s):  
Emine Acer ◽  
Emin Çadırlı ◽  
Harun Erol ◽  
Hasan Kaya ◽  
Mevlüt Şahin ◽  
...  
Keyword(s):  
Growth Velocity ◽  
Directionally Solidified ◽  
Zn Content ◽  
Zn Alloys

Effects of Growth Rates on Directionally Solidified Microstructure of Al-Ni-Y Ternary Alloy

2012 ◽  
Vol 562-564 ◽  
pp. 477-481
Author(s):  
Rui Xu
Keyword(s):  
Temperature Gradient ◽  
Directional Solidification ◽  
Ternary Alloy ◽  
Growth Rates ◽  
Optical Microscope ◽  
Experimental Results ◽  
Al Alloy ◽  
Directionally Solidified ◽  
X Ray Diffraction ◽  
X Ray

The directional solidification of the ternary Al alloy with composition of 2.6 at%Ni, 0.9 at%Y and 96.5 at% Al was carried out under the temperature gradient of 5 K/mm and the droping velocities of 0.5 mm/min, 1 mm/min, 5 mm/min, 10 mm/min, and 25 mm/min. The microstructure of the Al-Ni-Y ternary alloy was also analyzed by X-ray diffraction and optical microscope. The experimental results show that the microstructures of the Al-Ni-Y ternary alloy are consisted of ª-Al2, Al3Ni and Y4Ni6Al23phase when the alloy was directionally solidified in all directionally solidified rates in the experiments. No primary -Al can be found in the sample with directionally solidified rate of 0.5 mm/min. When the rates higher than 1 mm/min, the primary ª-Al can be observed. The microstructure of the directionally solidified alloy becomes finer and the primary ª-Al is smaller gradually with the increasing of growth velocities when the dropping rate of directional solidification is higher than 5 min/min. Two eutectic structures, Y4Ni6Al23andª-Al eutectic and Al3Ni and ª-Al eutectic, can be found when the dropping rate is higher than 10 mm/min.

scholarly journals Grain Selection and Texture Evolution in Directionally Solidified Al-Zn Alloys

2008 ◽  
Vol 39 (9) ◽  
pp. 2148-2160 ◽  
Author(s):  
Frédéric Gonzales ◽  
Michel Rappaz
Keyword(s):  
Texture Evolution ◽  
Directionally Solidified ◽  
Zn Alloys

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 growth parameters on the microstructure of directionally solidified Bi2Sr2CaCu2Oy

1990 ◽  
Vol 5 (9) ◽  
pp. 1834-1849 ◽  
Author(s):  
M. J. Cima ◽  
X. P. Jiang ◽  
H. M. Chow ◽  
J. S. Haggerty ◽  
M. C. Flemings ◽  
...  
Keyword(s):  
Growth Rate ◽  
Directional Solidification ◽  
Growth Rates ◽  
Growth Parameters ◽  
Directionally Solidified ◽  
Primary Solidification Phase ◽  
Float Zone ◽  
The Matrix ◽  
Laser Heated ◽  
Planar Growth

Laser-heated float zone growth was used to study the directional solidification behavior of Bi–Sr–Ca–Cu–O superconductors. The phases that solidify from the melt, their morphology, and their composition are altered by growth rate. Highly textured microstructures are achieved by directional solidification at all growth rates. The superconducting phase is found always to have the composition Bi2.5Sr2CaCu2.2Oy when grown from boules with composition 2:2:1:2 (BiO1.5:SrO:CaO:CuO). Planar growth fronts of Bi2.5Sr2CaCu2.2Oy are observed when the temperature gradient divided by the growth rate (G/R) is larger than 3 ⊠ 1011 K-s/m2 in 2.75 atm oxygen. Thus, the 2212 compound was observed to solidify directly from the melt at the slowest growth rates used in this study. Measurement of the steady-state liquid zone composition indicates that it becomes bismuth-rich as the growth rate decreases. Dendrites of the primary solidification phase, (Sr1−xCax)14Cu24Oy, form in a matrix of Bi2.5Sr2CaCu2.2Oy when G/R is somewhat less than 3 ⊠ 1011 K-s/m2. Observed microstructures are consistent with a peritectic relationship among Bi2.5Sr2CaCu2.2Oy, (Sr1−xCax)14Cu24Oy (x = 0.4), and a liquid rich in bismuth at elevated oxygen pressure. At lower values of G/R, Sr3Ca2Cu5Oy is the primary solidification phase and negligible Bi2.5Sr2CaCu2.2Oy forms in the matrix.

Directional Solidification of Mo5Si3-MoSi2 Eutectic

1998 ◽  
Vol 552 ◽  
Author(s):  
S. M. Borowicz ◽  
L. Heatherly ◽  
R. H. Zee ◽  
E. P. George
Keyword(s):  
Phase Diagram ◽  
High Temperature ◽  
Directional Solidification ◽  
Growth Rates ◽  
Eutectic Composition ◽  
Directionally Solidify ◽  
Growth Conditions ◽  
Floating Zone ◽  
Directionally Solidified ◽  
Melting Points

ABSTRACTThe Mo-Si phase diagram exhibits a Mo5Si3-MoSi2 eutectic at the 54% Si composition. Since the terminal phases have comparable melting points and are equidistant from the eutectic composition, there is the possibility of obtaining lamellar microstructures in this system. In addition, if the alloys are directionally solidified, there is the further possibility of obtaining aligned lamellae. In this study, a high temperature (xenon-arc-lamp) optical floating zone furnace is utilized to directionally solidify Mo-Si alloys of the eutectic composition. Growth conditions are systematically varied to investigate their effects on the solidification microstructure. Growth rates and rotation speeds are identified that result in lamellar microstructures.

scholarly journals 1300 K Compressive Properties of Directionally Solidified Ni-33Al-33Cr-1Mo

2000 ◽  
Vol 646 ◽  
Author(s):  
J. Daniel Whittenberger ◽  
S.V. Raj ◽  
Ivan. E. Locci
Keyword(s):  
Growth Rates ◽  
Cast Alloy ◽  
Directionally Solidified ◽  
Compressive Properties ◽  
Compressive Testing

ABSTRACTThe Ni-33Al-33Cr-1Mo eutectic has been directionally solidified by a modified Bridgeman technique at growth rates ranging from 7.6 to 508 mm/h to produce grain/cellular microstructures containing alternating plates of NiAl and Cr alloyed with Mo. The grains had sharp boundaries for slower growth rates (≤ 12.7 mm/h), while faster growth rates (≥ 25.4 mm/h) lead to cells bounded by intercellular regions. Compressive testing at 1300 K indicated that alloys DS'ed at rates between 25.4 to 254 mm/h possessed the best strengths which exceed that for the as-cast alloy.

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