scholarly journals Effect of Growth Rate on Microstructure Evolution in Directionally Solidified Ti-47Al Alloy

Heliyon ◽  
2022 ◽  
pp. e08704
Author(s):  
Tong Liu ◽  
Jing Tao ◽  
Xiaoye Cai ◽  
Dayong Chen ◽  
Jiansheng Li ◽  
...  
Keyword(s):  
Growth Rate ◽  
Microstructure Evolution ◽  
Directionally Solidified

Effect of growth rate on microstructure and microstructure evolution of directionally solidified Nb-Si alloys

2008 ◽  
Vol 1128 ◽  
Author(s):  
Yoshihito Sekito ◽  
Seiji Miura ◽  
Kenji Ohkubo ◽  
Tetsuo Mohri ◽  
Norihito Sakaguchi ◽  
...  
Keyword(s):  
Growth Rate ◽  
Orientation Relationship ◽  
Microstructure Evolution ◽  
Crystallographic Orientation ◽  
Floating Zone ◽  
Directionally Solidified ◽  
Solidification Direction ◽  
Arc Melting ◽  
Heat Treated ◽  
Crystallographic Orientation Relationship

AbstractIn the present work, Nb-18.1Si-1.5Zr alloy rods are produced with a growth rate ranging from 1.5 to about 1500 mm/h using the optical floating zone (OFZ) furnace. A part of each specimen is heat-treated at 1650 oC for 100 h. The microstructure was observed using SEM and TEM and analyzed using EPMA and EBSD.Eutectic-cells are observed in as-grown specimens with a growth rate of 150 mm/h or higher. It is found by EBSD analysis that the solidification direction of Nb is along <113> and that of Nb3Si is along <001], and {112} of Nb and {110) of Nb3Si are parallel. The present crystallographic orientation relationship between Nb and Nb3Si is different from that found in previous reports by several researchers. It was also confirmed that the heat-treated microstructure in the specimen grown by OFZ with a growth rate of 150 mm/h is similar to that in the heattreated specimen prepared by arc-melting.

Microstructure Evolution and Macro Segregation of Directionally Solidified Hypoeutectic and Hypereutectic Lead-Tin Alloys

2017 ◽  
Vol 895 ◽  
pp. 3-7
Author(s):  
K.V. Sreenivas Rao ◽  
N. Akhil
Keyword(s):  
Growth Rate ◽  
Directional Solidification ◽  
Microstructure Evolution ◽  
Solidification Rate ◽  
Unidirectional Solidification ◽  
Directionally Solidified ◽  
Tin Alloys ◽  
Alloy Increase ◽  
Set Up ◽  
Tin Content

Unidirectional solidification is preferred to multidirectional solidification for growing crystals in a particular direction. An experimental set-up consisting of Bridgman type of upward directional solidification was employed for the present investigation. The main aim of the present investigation was to assess the effect of unidirectional upward solidification on the segregation of off-eutectic Pb-Sn alloys at different translational speeds of the experimental set-up. Solidification experiments were conducted on hypoeutectic and hypereutectic Lead-Tin alloys. Different combinations of growth rate V and composition Co. were used to investigate their effect on longitudinal macro segregation. Macro segregation along the length of the samples was observed in hypoeutectic Pb-Sn alloys whereas no such macro segregation was observed in hypereutectic alloys. The intensity of longitudinal macro segregation was found to increase with the increase in initial tin content of the alloy, increase in distance from the chill end and decrease in the solidification rate.

Dependence of Microstructures and Mechanical Properties on the Growth Rate and Composition in Directionally Solidified Mg-Gd Alloys

2022 ◽  
Vol 327 ◽  
pp. 82-97
Author(s):  
He Qin ◽  
Guang Yu Yang ◽  
Shi Feng Luo ◽  
Tong Bai ◽  
Wan Qi Jie
Keyword(s):  
Mechanical Properties ◽  
Growth Rate ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Dendritic Structure ◽  
Directionally Solidified ◽  
Dendrite Morphology ◽  
Microstructural Parameters ◽  
Wide Range ◽  
Microstructures And Mechanical Properties

Microstructures and mechanical properties of directionally solidified Mg-xGd (5.21, 7.96 and 9.58 wt.%) alloys were investigated at a wide range of growth rates (V = 10-200 μm/s) under the constant temperature gradient (G = 30 K/mm). The results showed that when the growth rate was 10 μm/s, different interface morphologies were observed in three tested alloys: cellular morphology for Mg-5.21Gd alloy, a mixed morphology of cellular structure and dendritic structure for Mg-7.96Gd alloy and dendrite morphology for Mg-9.58Gd alloy, respectively. Upon further increasing the growth rate, only dendrite morphology was exhibited in all experimental alloys. The microstructural parameters (λ1, λ2) decreased with increasing the growth rate for all the experimental alloy, and the measured λ1 and λ2 values were in good agreement with Trivedi model and Kattamis-Flemings model, respectively. Vickers hardness and the ultimate tensile strength increased with the increase of the growth rate and Gd content, while the elongation decreased gradually. Furthermore, the relationships between the hardness, ultimate tensile strength, the growth rate and the microstructural parameters were discussed and compared with the previous experimental results.

Microstructural Evolution during the Directional Transient Solidification of a Hypomonotectic Al-0.9wt%Pb Alloy

2012 ◽  
Vol 730-732 ◽  
pp. 829-834
Author(s):  
Adrina P. Silva ◽  
Pedro R. Goulart ◽  
José Eduardo Spinelli ◽  
Amauri Garcia
Keyword(s):  
Growth Rate ◽  
Heat Flow ◽  
Thermal Parameters ◽  
Cooling Curves ◽  
Flow Conditions ◽  
Directionally Solidified ◽  
Microstructural Transition ◽  
Transient Heat Flow ◽  
Growth Laws ◽  
Casting Length

In the present study a hypomonotectic Al-0.9wt%Pb alloy was directionally solidified under transient heat flow conditions and the microstructure evolution was analyzed. The solidification thermal parameters such as the growth rate, the cooling rate and the temperature gradient were experimentally determined by cooling curves recorded by thermocouples positioned along the casting length. The monotectic structure was characterized by metallography and a microstructural transition was observed. From the casting cooled surface up to a certain position in the casting the microstructure was characterized by well-distributed Pb-rich droplets in the aluminum-rich matrix, followed by a mixture of fibers and strings of pearls from this point to the top of the casting. The interphase spacing (λ) and the diameter of Pb-rich particles were also measured along the casting length and experimental growth laws relating these microstructural features to the experimental thermal parameters are proposed.

Morphological Characteristics of W-Nanowires after Selective Etching

2014 ◽  
Vol 1004-1005 ◽  
pp. 24-27
Author(s):  
Wen Jia Wang ◽  
Zhi Long Zhao ◽  
Ming Tang ◽  
Jian Jun Gao
Keyword(s):  
Growth Rate ◽  
Temperature Gradient ◽  
Directional Solidification ◽  
Morphological Characteristics ◽  
Selective Dissolution ◽  
Stability Diagram ◽  
Selective Etching ◽  
Directionally Solidified ◽  
Solidification Furnace ◽  
Nial Matrix

An eutectic NiAl–1.5 at.% W alloy prepared by using directionally solidified (DS)was employed as a source for producing W-nanowires. Several growth rate of 8,15,25/s was respectively used at a temperature gradient of ~240 K/cm in a Bridgman-type directional solidification furnace. A combined stability diagram was applied to predict proper conditions for the selective dissolution of NiAl matrix to get W-wires. Etching in a mixture of HCl:H2O2released parallel aligned W-nanowires with a wire diameter of ~500 nm. Different morphologies, such as nanobelts, lotus-shaped, conical of W-nanowires are obtained at the different conditions.

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