Growth characteristics of directionally solidified Al2O3/YAG/ZrO2 ternary hypereutectic in situ composites under ultra-high temperature gradient

2011 ◽  
Vol 18 (1) ◽  
pp. 121-125 ◽  
Author(s):  
Hai-jun Su ◽  
Jun Zhang ◽  
Lin Liu ◽  
Heng-zhi Fu
Keyword(s):  
High Temperature ◽  
Temperature Gradient ◽  
Growth Characteristics ◽  
Directionally Solidified ◽  
In Situ Composites ◽  
High Temperature Gradient ◽  
Ultra High Temperature

High-Temperature-Gradient Casting of in Situ Multifilamentary Superconductors

1980 ◽  
pp. 343-349 ◽  
Author(s):  
J.-L. Fihey ◽  
M. Neff ◽  
R. Roberge ◽  
M. C. Flemings ◽  
S. Foner ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Gradient ◽  
High Temperature Gradient ◽  
Multifilamentary Superconductors

Microstructural Response of DS Nb-Silicide In-Situ Composites During High-Temperature Creep Testing

2000 ◽  
Vol 6 (S2) ◽  
pp. 376-377
Author(s):  
B.P. Bewlay ◽  
S.D. Sitzman
Keyword(s):  
High Temperature ◽  
Electron Backscatter Diffraction ◽  
Czochralski Method ◽  
Longitudinal Section ◽  
Creep Testing ◽  
Directionally Solidified ◽  
Creep Tests ◽  
In Situ Composites ◽  
Structural Applications

Directionally solidified (DS) in-situ composites based on (Nb) and Nb silicides, such as Nb5Si3 and Nb3Si, are being investigated for high-temperature structural applications. The use of alloying additions, such as Hf, Ti and Mo, to these silicides is required to enhance their properties. The present paper describes the microstructural response of a DS Nb-silicide based composite to creep testing.The composites investigated were directionally solidified from a molten alloy using the Czochralski method as described previously. Creep tests were conducted at 1200°C to strains of up 50%. Microstructure and microtexture characterizations were performed using scanning electron microscopy, electron microprobe analysis (EMPA), and electron backscatter diffraction pattern analysis (EBSP).Microstructures of the longitudinal section of a DS composite generated from a Nb-12.5Hf-33Ti- 16Si alloy are shown in Figure 1 in the as-DS (left hand side) and the DS+creep tested conditions (right hand side).

Heat Treatment Microstructures of a Directionally Solidified Nickel Base Superalloy under High Temperature Gradient

2014 ◽  
Vol 788 ◽  
pp. 519-524
Author(s):  
Wei Guo Zhang ◽  
Xue Mei Yi ◽  
Chu Ang Feng
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Temperature Gradient ◽  
Grain Boundary ◽  
Solution Treatment ◽  
Grain Boundary Sliding ◽  
Chinese Script ◽  
Nickel Base Superalloy ◽  
Directionally Solidified ◽  
High Temperature Gradient

The heat treatment of a directionally solidified superalloy under high temperature gradient with different dendritic size was studied. The evolution rules of each phase in DZ125 alloy after heat treatment were analyzed. The results show that γ' phase presents cube and uniform distribution after heat treatment. Its size is about 0.4μm and its area ratio is about 65%. MC carbide transforms into MC(2) carbide with high concentration of Hf. The morphology of MC carbide changes from Chinese-script to block and its size reduces gradually with increasing solidification rate under directional solidification. There is bulk γ' phase around carbide. MC(2) carbide and γ' phase in the grain boundary form chain along grain boundary, and effectively retard grain boundary sliding. γ+γ' eutectic is basically eliminated by solution treatment and only a little γ+γ' eutectic exists around carbide.

Ti-Modified Niobium-Silicide Based Directionally Solidified in-situ Composites

1996 ◽  
Vol 460 ◽  
Author(s):  
B. P. Bewlay ◽  
M. R. Jackson ◽  
H. A. Lipsitt
Keyword(s):  
Solid Solution ◽  
Fracture Toughness ◽  
High Temperature ◽  
Cold Crucible ◽  
Directionally Solidified ◽  
In Situ Composites ◽  
Czochralski Crystal Growth ◽  
Three Phase ◽  
Binary Eutectic

ABSTRACTThis paper examines microstructure-property relationships in high-temperature directionally solidified (DS) in-situ composites based on Nb silicides, such as Nb3Si and Nb5Si3. These in-situ composites are based on the Nb3Si-Nb binary eutectic, and are alloyed with Ti. They were prepared using cold crucible Czochralski crystal growth. Ternary Nb-Ti-Si alloys with Ti concentrations from 9 to 45%, and Si concentrations from 10 to 25%, were directionally solidified to generate aligned two- and three-phase composites containing a Nb solid solution with Nb3Si and Nb5Si3 silicides. Fracture toughness values generally greater than 10 MPa√m were measured in these composites. For a given Si concentration, the fracture toughness of the Ti-containing composites was increased ∼ 6 MPa√m over that of the binary alloy composites. The effects of Si concentration, and a range of Nb:Ti ratios, on microstructure, phase equilibria, and fracture toughness were examined.

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