Observation of the Dissolution of Topologically Close Packed Phases by an Additional Heat Treatment in Third Generation Nickel-Based Single Crystal Superalloy Turbine Blades

2018 ◽  
Vol 20 (7) ◽  
pp. 1700987 ◽  
Author(s):  
KeeHyun Park ◽  
Paul Withey
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Turbine Blades ◽  
Single Crystal Superalloy ◽  
Third Generation ◽  
Additional Heat ◽  
Additional Heat Treatment ◽  
Topologically Close Packed

Formation of Secondary Phases in the Boundary between Surface Defect Grains and Matrix in Third Generation Nickel-Based Single Crystal Superalloy Turbine Blades

2018 ◽  
Vol 941 ◽  
pp. 766-771
Author(s):  
Kee Hyun Park ◽  
Paul Withey
Keyword(s):  
Grain Boundary ◽  
Single Crystal ◽  
Surface Defect ◽  
Turbine Blades ◽  
High Resolution Electron Microscopy ◽  
Boundary Region ◽  
Single Crystal Superalloy ◽  
Third Generation ◽  
Secondary Phases ◽  
Stray Grains

Ni-based single crystal superalloy turbine blades have excellent mechanical strength and resistance to corrosion and oxidation due to a uniformly distributed gamma prime phase in a gamma matrix. However, defect grains have been often found on the surface of turbine blades after manufacturing, which can be potential sites of crack initiation. In this study, several different types of surface defect grains formed in third generation Ni-based single crystal turbine blades, such as stray grains, freckle chain grains, equiax grains, and a new grain formed in surface scale, had been investigated. The grain boundary regions were observed by high resolution electron microscopy. Although the formation mechanism of each grain defect is different, secondary phases, such as rhenium-rich particles, have been always found in each grain boundary. In addition, depending on the existence of the secondary phases as well as the size of defect grains, different microstructures were observed even in the same defect grain boundary. Finally, the observed results suggest that if there is any boundary region in a turbine blade, secondary phases, such as Re-rich particles, can be found.

Investigation on a ramp solution heat treatment for a third generation nickel-based single crystal superalloy

2017 ◽  
Vol 723 ◽  
pp. 922-929 ◽  
Author(s):  
Yanbin Zhang ◽  
Lin Liu ◽  
Taiwen Huang ◽  
Quanzhao Yue ◽  
Dejian Sun ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Solution Heat Treatment ◽  
Single Crystal Superalloy ◽  
Third Generation

LCF, HCF and VHCF life sensitivity to solution heat treatment of a third-generation Ni-based single crystal superalloy

2020 ◽  
Vol 130 ◽  
pp. 105247 ◽  
Author(s):  
Luciana Maria Bortoluci Ormastroni ◽  
Lorena Mataveli Suave ◽  
Alice Cervellon ◽  
Patrick Villechaise ◽  
Jonathan Cormier
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Solution Heat Treatment ◽  
Single Crystal Superalloy ◽  
Third Generation

scholarly journals General View of Rhenium-Rich Particles along Defect Grain Boundaries Formed in Nickel-Based Single-Crystal Superalloy Turbine Blades: Formation, Dissolution and Comparison with Other Phases

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1201
Author(s):  
KeeHyun Park ◽  
Paul Withey
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Single Crystal ◽  
Power Plants ◽  
Fine Particles ◽  
Turbine Blades ◽  
Base Material ◽  
Boundary Region ◽  
Single Crystal Superalloy ◽  
General View

Nickel-based single-crystal superalloy turbine blades have been widely used in engines of aircrafts or power plants, but some defect grains are often found on the surface of the blade after full heat treatment or even after casting. Rhenium-rich particles, as well as an intermediate layer, were almost always detected along any defect grain boundary region, if it existed, from a low-angle grain boundary to a high-angle boundary. The particles were also found on the top surface of the base material. The composition and morphology of the particles were different from the most common topologically close packed phases or a fine particle with similar morphology detected at the boundary region between a recrystallized grain and a matrix grain. An additional heat treatment could completely dissolve the fine particles. Furthermore, any rhenium-rich particles were not re-formed after achieving uniform distribution of the alloying elements.

Microstructures of Low Angle Boundaries of a Third Generation Single Crystal Superalloy DD9

2017 ◽  
Vol 898 ◽  
pp. 413-421
Author(s):  
Wan Peng Yang ◽  
Jia Rong Li ◽  
Shi Zhong Liu ◽  
Jin Qian Zhao ◽  
Zhen Xue Shi ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Solution Heat Treatment ◽  
Discrete Distribution ◽  
Single Crystal Superalloy ◽  
Third Generation ◽  
Cast State ◽  
Aging Heat Treatment ◽  
Treatment Processes

The microstructures of low angle boundaries (LABs) of a third generation single crystal superalloy DD9 in as-cast state and after different heat treatment processes were studied by optical microscopy (OM) and field emission scanning electron microscopy (FESEM). The results showed that the as-cast LABs of DD9 alloy consisted of rod-like and bulk γ' phases with γ matrix between them, and there were eutectic γ-γ' precipitating at the LABs, as well as small amounts of discrete distribution of carbides. The γ' phase locateed at the grain boundaries was larger than that distributed on both sides of the grain boundaries. After the solution heat treatment, as-cast eutectic γ-γ' at LABs dissolved completely, and rod-like γ' phase was still found at some LABs. Meanwhile, the LABs were inclined to be straight compared to the as-cast state. The primary aging heat treatment made γ' phase at the LABs dissolved completely, and the secondary aging heat treatment resulted little change in the morphology of the LABs. Thus, the effect of the primary aging heat treatment on the microstructures of the LABs was greater than that of the secondary aging heat treatment.

New Phases in a Multicomponent High Ruthenium Single Crystal Superalloy

2005 ◽  
Vol 475-479 ◽  
pp. 655-660 ◽  
Author(s):  
Q. Feng ◽  
L.J. Rowland ◽  
T.M. Pollock
Keyword(s):  
Single Crystal ◽  
Dendritic Structure ◽  
Thermal Exposure ◽  
Single Crystal Superalloy ◽  
Heusler Phase ◽  
Topologically Close Packed ◽  
Tcp Phases ◽  
Δ Phase

Three unusual Ru-rich phases have been identified in a multicomponent Ni-base single crystal superalloy, including a L21 Ru2AlTa Heusler phase, a B2 RuAl phase and a hcp Re(Ru)-rich δ phase. These phases have their own preferential precipitation location within the dendritic structure. No conventional topologically-close-packed (TCP) phases have been observed with thermal exposure at 950oC for 1500 hours.

scholarly journals Creep Damage Repair of a Nickel-Based Single Crystal Superalloy Based on Heat Treatment

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 623
Author(s):  
Xiaoyan Wang ◽  
Meng Li ◽  
Yuansheng Wang ◽  
Chengjiang Zhang ◽  
Zhixun Wen
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Creep Damage ◽  
Primary Creep ◽  
Single Crystal Superalloy ◽  
Secondary Creep ◽  
Creep Life ◽  
Phase Coarsening ◽  
Damage Repair ◽  
Creep Time

Taking nickel-based single crystal superalloy DD6 as the research object, different degrees of creep damage were prefabricated by creep interruption tests, and then the creep damage was repaired by the restoration heat treatment system of solid solution heat treatment and two-stage aging heat treatment. The results show that with the creep time increasing, the alloy underwent microstructure evolution including γ′ phase coarsening, N-type rafting and de-rafting. After the restoration heat treatment, the coarse rafted γ′ phase of creep damaged specimens dissolved, precipitated, grew up, and became cubic again. Except for the specimens with creep interruption of 100 h, the γ′ phase can basically achieve the same arrangement as the γ′ phase of the original sample. The comparison of the secondary creep test shows that the steady-state creep stage of the test piece after the restoration heat treatment is relatively increased, and the total creep life can reach the same level as the primary creep life. The high temperature creep properties of the tested alloy are basically recovered, and the restoration heat treatment effect is good.

Creep Behavior of a 4.5% Re Nickel-Base Single Crystal Superalloy at High Temperature

2015 ◽  
Vol 750 ◽  
pp. 139-144 ◽  
Author(s):  
De Long Shu ◽  
Su Gui Tian ◽  
Xin Ding ◽  
Jing Wu ◽  
Qiu Yang Li ◽  
...  
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Single Crystal ◽  
Deformation Mechanism ◽  
Creep Property ◽  
Single Crystal Superalloy ◽  
Micro Cracks ◽  
Initiation And Propagation ◽  
Temperature Ranges ◽  
Nickel Base

By means of heat treatment and creep property measurement, an investigation has made into the creep behaviors of a containing 4.5% Re nickel-base single crystal superalloy at high temperature. Results show that the elements W, Mo and Re are enriched in the dendrite arm regions, the elements Al, Ta, Cr and Co are enriched in the inter-dendrite region, and the segregation extent of the elements may be obviously reduced by means of heat treatment at high temperature. In the temperature ranges of 1070--1100 °C, the 4.5% Re single crystal nickel-based superallloy displays a better creep resistance and longer creep life. The deformation mechanism of the alloy during steady state creep is dislocations slipping in the γ matrix and climbing over the rafted γ′ phase. In the later stage of creep, the deformation mechanism of alloy is dislocations slipping in the γ matrix, and shearing into the rafted γ′ phase, which may promote the initiation and propagation of the micro-cracks at the interfaces of γ/γ′ phases up to the occurrence of creep fracture.

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