Effects of Re on Microstructure of Ni3Al-Based Single Crystal Superalloys

2014 ◽  
Vol 788 ◽  
pp. 498-503 ◽  
Author(s):  
Jing Yang Chen ◽  
Ming Xue ◽  
Xin Tang ◽  
La Mei Cao
Keyword(s):  
Single Crystal ◽  
Volume Fraction ◽  
Lattice Misfit ◽  
Alloying Elements ◽  
Microstructural Stability ◽  
Segregation Ratios ◽  
Kinetics Of ◽  
Liquidus Temperatures

The effects of Re on solidus/liquidus temperatures, solidification segregation characteristics of alloying elements, γ′ morphology and volume fraction as well as microstructural stability at 1150 °C have been investigated in two experimental Ni3Al-based single crystal superalloys with and without Re (1.0 wt%) addition. The results indicated that Re addition increased the solidus/liquidus temperatures. The segregation characteristics of Ni3Al-based single crystal superalloys were similar with Ni-based single crystal superalloys, and the solidification segregation ratios of W and Mo increased slightly due to Re addition. Meanwhile, Re addition resulted in more negative lattice misfit, more cuboidal γ′ phase and higher γ′ volume fraction. The kinetics of γ′ coarsening and rafting at 1150 °C was lowered substantially compared with the addition of Re.

Strengthening Mechanisms in Some Single-Crystal Superalloys

2005 ◽  
Vol 475-479 ◽  
pp. 623-626 ◽  
Author(s):  
Yuichiro Koizumi ◽  
Hiroshi Harada
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Creep Behavior ◽  
Lattice Misfit ◽  
Alloying Elements ◽  
Strengthening Mechanisms ◽  
Interfacial Dislocation ◽  
Nickel Base

The creep behavior and microstructure of several nickel-base single-crystal superalloys after high-temperature low-stress creep have been investigated. These alloys were designed with varying content of the alloying elements Mo and Ru. At 1100°C and 137 MPa, the large g/g¢ lattice misfit in negative with the addition of Mo leads to the formation of dense interfacial dislocation networks. These dislocation networks are effective to strengthen the alloys during creep by preventing the penetration of the g dislocations into the g¢ phase.

Influence of Ru on the Microstructure of Ni-Base Single Crystal Superalloys

2011 ◽  
Vol 306-307 ◽  
pp. 562-571 ◽  
Author(s):  
Fei Sun ◽  
Jian Xin Zhang
Keyword(s):  
Single Crystal ◽  
Volume Fraction ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Solid Solution Strengthening ◽  
Refractory Elements ◽  
Tcp Phases ◽  
Solution Strengthening ◽  
Strengthening Element ◽  
Partitioning Behavior

Addition of Ru in Ni-base single crystal superalloys had been used to improve the elevated temperature strength and other multiple properties. Significant decreases in stacking fault energy of the γ phase and the volume fraction of γ′ phase are observed with the addition of Ru. As well as serving as an effective solid-solution strengthening element in high refractory content Ni-base single crystal superalloys, Ru additions are able to effectively strengthen both the γ and γ′ phases and suppress the formation of TCP phases. Due to the changes in the partitioning behavior of elements and the slight decrease in the supersaturation of refractory elements in γ phase associated with Ru additions, high temperature creep resistance and the microstructural stability of the alloy are improved remarkable. The influence of Ru on the microstructure of Ni-base single crystal superalloys is reviewed.

Role of Cobalt in the Microstructural Stability of Single Crystal Superalloys

2016 ◽  
Vol 849 ◽  
pp. 557-562 ◽  
Author(s):  
Jing Yang Chen ◽  
Qing Li ◽  
Jie Li ◽  
Xin Tang ◽  
Cheng Bo Xiao
Keyword(s):  
Single Crystal ◽  
Volume Fraction ◽  
Thermal Exposure ◽  
Precipitate Size ◽  
Microstructural Stability ◽  
Tcp Phases ◽  
The Stability ◽  
Co Addition ◽  
Good Agreement

The effects of Co additions on the evolution of γ' precipitates and topologically close-packed (TCP) phases during thermal exposure at 950 °C were investigated for two Ni-based single crystal superalloys with 7.9 wt.% Co and 9.1 wt.% Co. The results indicated that the γ′ morphology was not affected by Co content, whereas γ′ volume fraction decreased and precipitate size increased due to lower Co addition after standard heat treatment. The coarsening of γ′ precipitates in both alloys was controlled by diffusion. The γ′ coarsening rate increased, while the stability of γ′ volume fraction decreased due to lower level of Co addition during 950 °C thermal exposure because more Co addition suppressed the diffusion process. High Co addition promoted the formation of μ phase after thermal exposure at 950 °C for 1000 h due to higher γ′ volume fraction, more stable γ′ volume fraction and higher electron vacancy number. The experimental results of μ phase precipitation showed good agreement with thermodynamic calculation by JMatPro.

Influences of W and Al on the Microstructure and Stress-Rupture Property of Re-Free Ni-Based Single Crystal Superalloys

2017 ◽  
Vol 898 ◽  
pp. 492-497
Author(s):  
Jing Yang Chen ◽  
Qing Li ◽  
Ming Jun Zhang ◽  
Xin Tang ◽  
Cheng Bo Xiao
Keyword(s):  
Single Crystal ◽  
Volume Fraction ◽  
Base Alloy ◽  
Rupture Life ◽  
Solidus Temperature ◽  
Stress Rupture ◽  
Stress Rupture Life ◽  
Stress Rupture Property ◽  
Matrix Channel ◽  
Liquidus Temperatures

The influence of W and Al on the solidus and liquidus temperatures, microstructure and stress-rupture property at 980 °C/250 MPa was investigated in three Re-free experimental Ni-based single crystal superalloys. The results indicated that the solidus temperature increased for 14.0 °C and 9.8 °C by adding 0.84 wt.% W only and adding 0.45 wt.% Al and 0.44 wt.% W to the base alloy, respectively. The γ′ morphology changed from nearly cuboidal in the base alloy to cuboidal by adding 0.45 wt.% Al and 0.44 wt.% W. The volume fraction of γ′ precipitates increased, while the γ channel width decreased after adding Al and W. The additions of Al and W improved the stress-rupture life at 980 °C/250 MPa because of higher γ′ volume fraction, narrower γ matrix channel and more complete rafting structure.

Influence of Ru and Cr on the Heat-Treated Microstructure of Ni-Based Superalloys

2007 ◽  
Vol 546-549 ◽  
pp. 1207-1210 ◽  
Author(s):  
W.B. Wang ◽  
Qiang Feng ◽  
L.J. Carroll ◽  
Y.L. Wang ◽  
Guo Liang Chen ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Lattice Misfit ◽  
Microstructural Stability ◽  
Scanning Calorimetry ◽  
Heat Treated ◽  
Tcp Phases ◽  
Microstructural Instability ◽  
Cr Addition ◽  
Neutral Effect ◽  
Liquidus Temperatures

The effects of ruthenium and chromium contents have been investigated on phase transformation temperatures and the morphology of γ’ precipitates as well as microstructural stability in high refractory Ni-base superalloys. The solidus and liquidus temperatures were determined by differential scanning calorimetry (DSC), suggesting that the addition of Cr resulted in a decrease in solidus/liquidus temperatures while the Ru addition (3.5 at.%) had the neutral effect. The morphology of γ’ precipitates in the heat-treated microstructure was changed under the influence of the Cr and Ru additions, suggesting that Ru and Cr contents affected the γ−γ’ lattice misfit through changes in the associated partitioning to the constituent phases. The microstructural instability has been investigated at 1000 oC. High levels of Cr addition (8 at.%) strongly promoted the formation of TCP phases, while Ru improved the microstructural stability to some extent.

Microstructural Stability of a Single Crystal Superalloy DD10 under Stressed and Un-Stressed Thermal Exposure at 980 °C

2013 ◽  
Vol 721 ◽  
pp. 3-7 ◽  
Author(s):  
Jing Yang Chen ◽  
Li Jun Liu ◽  
Xiang Hui Li ◽  
Ming Xue ◽  
La Mei Cao
Keyword(s):  
Tensile Stress ◽  
Single Crystal ◽  
Lattice Misfit ◽  
Thermal Exposure ◽  
Single Crystal Superalloy ◽  
Microstructural Stability ◽  
Misfit Stress ◽  
Topologically Close Packed ◽  
Tcp Phase ◽  
Applied Tensile Stress

The effects of applied tensile stress on the microstructural stability of a third generation single crystal superalloy DD10 have been investigated under stressed and un-stressed thermal exposure at 980 °C. The results indicated that μ phase precipitated in the dendrite core after both stressed and un-stressed thermal exposure at 980 °C for 450 h. The μ phase formation, γ′ coarsening and rafting processes were promoted by the applied tensile stress. However, the precipitation of μ phase was not sensitive to the magnitude of applied tensile stress. Meanwhile, the applied tensile stress did not affect the type and morphology of the topologically close packed (TCP) phase. It is suggested that the interaction of the applied tensile stress and the misfit stress decreased the lattice misfit between μ phase and γ matrix and promoted the formation of μ phase.

Microstructural characterization of a rapidly solidified Al-Fe-V-Si alloy for elevated temperature applications

1988 ◽  
Vol 46 ◽  
pp. 550-551
Author(s):  
R. E. Franck ◽  
J. A. Hawk ◽  
G. J. Shiflet
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Grain Growth ◽  
Volume Fraction ◽  
Microstructural Characterization ◽  
Second Phase ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Temperature Applications

Rapid solidification processing (RSP) is one method of producing high strength aluminum alloys for elevated temperature applications. Allied-Signal, Inc. has produced an Al-12.4 Fe-1.2 V-2.3 Si (composition in wt pct) alloy which possesses good microstructural stability up to 425°C. This alloy contains a high volume fraction (37 v/o) of fine nearly spherical, α-Al12(Fe, V)3Si dispersoids. The improved elevated temperature strength and stability of this alloy is due to the slower dispersoid coarsening rate of the silicide particles. Additionally, the high v/o of second phase particles should inhibit recrystallization and grain growth, and thus reduce any loss in strength due to long term, high temperature annealing.The focus of this research is to investigate microstructural changes induced by long term, high temperature static annealing heat-treatments. Annealing treatments for up to 1000 hours were carried out on this alloy at 500°C, 550°C and 600°C. Particle coarsening and/or recrystallization and grain growth would be accelerated in these temperature regimes.

Sign in / Sign up

Export Citation Format

Share Document