MICROSTRUCTURE AND MICROSEGREGATION IN A Ni--BASED SINGLE CRYSTAL SUPERALLOY DIRECTIONALLY SOLIDIFIED UNDER HIGH THERMAL GRADIENT

2010 ◽  
Vol 2010 (1) ◽  
pp. 77-83 ◽  
Author(s):  
Gang LIU ◽  
Lin LIU ◽  
Xinbao ZHAO ◽  
Weiguo ZHANG ◽  
Tao JIN ◽  
...  
Keyword(s):  
Single Crystal ◽  
Thermal Gradient ◽  
Single Crystal Superalloy ◽  
Directionally Solidified ◽  
High Thermal Gradient

scholarly journals Solidification Characteristics and as-Cast Microstructure of Rhenium-Containing Single Crystal Superalloys under High Thermal Gradient Directional Solidification

2011 ◽  
Vol 278 ◽  
pp. 423-427
Author(s):  
Gang Liu ◽  
Lin Liu ◽  
Xin Bao Zhao ◽  
Tai Wen Huang ◽  
Jun Zhang
Keyword(s):  
Single Crystal ◽  
Thermal Gradient ◽  
Liquidus Temperature ◽  
Eutectic Reaction ◽  
Directionally Solidified ◽  
High Thermal Gradient ◽  
Epma Analysis ◽  
Segregation Ratios ◽  
Eutectic Formation ◽  
Constituent Elements

A series of Ni-base single crystal superalloys with increasing contents of Re (3-6 wt. %) were directionally solidified under a high thermal gradient of approximately 250 K/cm. It shows that Re additions slightly increases the liquidus temperature, but decreases the eutectic reaction and γ′-solvus temperature of the experimental alloys. EPMA analysis indicates that Re addition strongly influences the segregation ratios of the constituent elements, particularly for Cr, Mo and W, and thus results in more severe dendrite segregation and large amount of eutectic formation in the as-cast microstructures.

Effect of Thermal Gradient on Solidification Microstructure in the Ni-Base Single Crystal Superalloy CMSX10

2008 ◽  
Vol 273-276 ◽  
pp. 361-366 ◽  
Author(s):  
S.H. Kim ◽  
J.M. Kim ◽  
H.J. Lee ◽  
S.D. Son ◽  
J.H. Lee ◽  
...  
Keyword(s):  
Single Crystal ◽  
Directional Solidification ◽  
Thermal Gradient ◽  
Solidification Rate ◽  
Planar Interface ◽  
Single Crystal Superalloy ◽  
Thermal Gradients ◽  
High Thermal Gradient ◽  
Cooling Media ◽  
Cold Chamber

A single crystal superalloy including 6 wt.% Re, CMSX10 was studied by directional solidification at various thermal gradients, 13 ~ 23oC/mm and solidification rates, 1~100 μm/s. A high thermal gradient could be obtained by applying the liquid metal, such as Ga-In, as a cooling media in directional solidification apparatus, and also by adjusting the cold chamber in the Bridgman system. As increasing the solidification rate, the planar interface changed to cellular and dendritic interfaces. The higher thermal gradient contributed to reducing the dendrite arm spacing effectively, which results in reducing the size of eutectic, as well as higher solidification rate. The length of the mushy zone decreased with increasing the thermal gradient and increased with increasing the solidification rate.

Interface Morphologies and Microstructure of a Single Crystal Superalloy under High Thermal Gradient Directional Solidification

2005 ◽  
Vol 475-479 ◽  
pp. 665-668 ◽  
Author(s):  
Lin Liu ◽  
Jun Zhang ◽  
Taiwen Hang ◽  
Heng Zhi Fu
Keyword(s):  
Single Crystal ◽  
Directional Solidification ◽  
Cooling Rate ◽  
Thermal Gradient ◽  
Cellular Structure ◽  
Single Crystal Superalloy ◽  
Withdrawal Rate ◽  
High Rate ◽  
High Thermal Gradient ◽  
Withdrawal Speed

The interface morphologies single crystal superalloys CMSX-2 has been studied over a range of cooling rate with large variations in withdrawal speed in directional solidification. The superfine cellular structure was obtained under both high thermal gradient up to 1000K/cm and fast withdrawal rate up to 1mm/sec. The high rate directional solidification results in reduction in primary and secondary dendrite arm spacing, refinement of λ’ phase, reduced microsegregation of alloying elements and smaller size of γ-γ’ eutectics.

Effect of Hf Content on Oxidation Resistance of Single Crystal Superalloy at 1000°C

2014 ◽  
Vol 915-916 ◽  
pp. 562-566 ◽  
Author(s):  
Z.X. Shi ◽  
Shi Zhong Liu ◽  
M. Han ◽  
J.R. Li
Keyword(s):  
Grain Size ◽  
Single Crystal ◽  
Oxide Scale ◽  
Oxide Layer ◽  
Oxidation Resistance ◽  
Isothermal Oxidation ◽  
Single Crystal Superalloy ◽  
Ambient Atmosphere ◽  
Directionally Solidified ◽  
Better Than

The specimens of single crystal superalloy DD6 with 0.10% Hf and 0.47% Hf were prepared in the directionally solidified furnace. The effect of Hf content on the isothermal oxidation resistance of the second generation single crystal superalloy DD6 was studied at 1000°Cin ambient atmosphere. Morphology of oxides was examined by SEM, and their composition was analyzed by XRD and EDS. The experimental results show that the oxidation resistance of DD6 alloy with 0.47% Hf is better than that of the alloy with 0.10% Hf. The alloy with different Hf content all obeys parabolic rate law during oxidation for 100h at 1000°C. The increase of Hf content can promote the Al2O3 formation and decreases the proportion of NiO. The oxide grain size and the thickness of the oxide layer all reduce with increasing of Hf content. The oxide scale of the alloy with different Hf content is made up of an outer NiO layer with a small amount of Co3O4, inner Al2O3 and Cr2O3 layer with a small amount of TaO2.

Directional Solidification Behavior of CMSX-6 Superalloy

2014 ◽  
Vol 788 ◽  
pp. 554-559
Author(s):  
Shuai Zheng ◽  
Yu Liang Jia ◽  
Jiao Tang
Keyword(s):  
Single Crystal ◽  
Directional Solidification ◽  
Thermal Gradient ◽  
First Generation ◽  
Primary Dendrite ◽  
Solidification Rate ◽  
Experimental Results ◽  
Single Crystal Superalloy ◽  
Solidification Behavior ◽  
Rate Range

The directional solidification behavior of a first generation single crystal superalloy CMSX-6 was investigated. The solidification rate range in 25μm/s to 100μm/s and a thermal gradient G of 30K/cm were used for the present study. The experimental results show that the primary dendrite arm space (PDAS) decreased from (432±8) μm to (369±4) μm as the solidification rate increased, and the sizes of the eutectic pools also decreased as the solidification rate increased. And the volume fractions of eutectic γ/γ' were about 7% to 9% with different solidification rate. The γ/γ'- eutectic was comprised with coarse γ' phase and fine γ/γ' network. The morphology of the γ/γ’ eutectic supported the possibility that the solidification of γ/γ’ eutectic initiates with the formation of fine γ/γ’.

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