Grain Competitive Growth Prediction during Solidification in Single Crystal Superalloy DD6 Castings

2014 ◽  
Vol 783-786 ◽  
pp. 2148-2153
Author(s):  
Hai Peng Jin ◽  
Jia Rong Li
Keyword(s):  
Single Crystal ◽  
Cross Sections ◽  
Three Dimensional ◽  
Single Crystal Superalloy ◽  
Competitive Growth ◽  
Chill Surface ◽  
Stress Orientation ◽  
Ca Model ◽  
Ebsd Method ◽  
Competition Growth

Competitive growth and grain selection were simulated and analyzed during the directional solidification with the conditions for single crystal superalloy DD6 castings using Commercial software, ProCAST. A three dimensional cellular automaton (CA) model coupled with finite-element (FE) heat flow calculation was applied. Measurements at the grain scale were made using the EBSD method at the cross sections in the starter block and grain selector at an interval of 4 mm from the chill surface. The grain characteristics and the rules of competition growth were obtained. The validity of the simulation results were compared with those of the experiment. It concluded that the model-predicted tendency shows satisfactory agreement with the experiment. Increasing the distance from the chill decreases the number of grains, increases the radius of grains and drives the crystallization orientation of grains to principal stress orientation.

Microstructures of Low Angle Boundaries of the Second Generation Single Crystal Superalloy DD6

2011 ◽  
Vol 284-286 ◽  
pp. 1584-1587
Author(s):  
Zhen Xue Shi ◽  
Jia Rong Li ◽  
Shi Zhong Liu ◽  
Jin Qian Zhao
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Thin Layer ◽  
Single Crystal ◽  
Second Generation ◽  
Three Dimensional ◽  
Single Crystal Superalloy ◽  
Transition Electron ◽  
Scanning Electron

The specimens of low angle boundaries were machined from the second generation single crystal superalloy DD6 blades. The microstructures of low angle boundaries (LAB) were investigated from three scales of dendrite, γ′ phase and atom with optical microscopy (OM), scanning electron microscope (SEM), transition electron microscope (TEM) and high resolution transmission electrion microscopy (HREM). The results showed that on the dendrite scale LAB is interdendrite district formed by three dimensional curved face between the adjacent dendrites. On the γ′ phase scale LAB is composed by a thin layer γ phase and its bilateral imperfect cube γ′ phase. On the atom scale LAB is made up of dislocations within several atom thickness.

Prediction of Grain Formation and Defects during Solidification in Single Crystal Superalloy Castings

2021 ◽  
Vol 1035 ◽  
pp. 819-826
Author(s):  
Hai Peng Jin ◽  
Shi Zhong Liu ◽  
Hong Ji Xie ◽  
Jia Rong Li
Keyword(s):  
Single Crystal ◽  
Large Deviation ◽  
Solidification Process ◽  
Orientation Distribution ◽  
Single Crystal Superalloy ◽  
Competitive Growth ◽  
Initial Nucleation ◽  
Grain Formation ◽  
Orientation Deviation ◽  
Stray Grains

Numerical simulation and prediction of grain formation and defects, including the stray grain and high angle orientation deviation during directional solidification process of a single crystal superalloy hollow turbine blade are experimentally conducted by means of commercial software ProCAST and backscattering scanning electron microscope. The results show that the initial nucleation amount at the beginning section of the starter block is 104 of magnitude, and the number of grains decreases gradually with the competitive growth, and the number is about 100 at the spiral of the selector. And the orientation distribution of grains is close to <001> direction, with the orientation deviation between 10° and 15°. Moreover, with the increase of withdrawal rate, the curvature of isoline of liquidus of single crystal blade increases, and the tendency to form stray grains defects increases. The grain with a large deviation from orientation blocks the growth of other grains at the first rotating transition site of the selector, and then gradually grows and solidifies to form the final blade.

Microstructure Evolution of a Single Crystal Superalloy after Tensile Fracture at Different Temperature

2013 ◽  
Vol 721 ◽  
pp. 262-265
Author(s):  
Zhen Xue Shi ◽  
Shi Zhong Liu ◽  
J. Yu ◽  
M. Han ◽  
J.R. Li
Keyword(s):  
Single Crystal ◽  
Microstructure Evolution ◽  
Stacking Faults ◽  
Single Crystal Superalloy ◽  
Tensile Fracture ◽  
Matrix Channel ◽  
Stress Orientation ◽  
Transmission Electron ◽  
Strength Behavior ◽  
The Matrix

The tensile property tests of DD6 single crystal superalloy were performed at 25°C, 760°C and 980°C in air. Detailed microstructure evolution was carried out on the alloy to illuminate the γ phase and dislocation structure after tensile fracture by scanning electron microscope and transmission electron microscopy. The results show that the alloy has the maximum tensile strength and the minimum plasticity at 760°C. DD6 alloy has the same anomalous yield strength behavior with other single crystal superalloys. The γ phase hasve a little extension in the stress orientation after tensile fracture at 25°C. The γ phase morphology still maintains cubic after tensile fracture at 760°C. The γ phase is no longer cubic and changes into rectangular solid in the specimen tensile ruptured at 980°C. The vertical γ matrix becomes thinner and horizontal γ matrix becomes thicker slightly. The γ phase is no longer cubic and changes into rectangular solid. High density dislocations are present in the matrix channels and a lot of superlattice stacking faults are seen within γ phases in the sample tested at 25°C. A large quantities of superlattice stacking faults within γ phase and a lot of dislocations tangling in matrix channel are all present in the sample tested at 760°C. The dislocation networks have homogeneously formed at γ/γ interface in the sample tested at 980°C.

Grain Competition Mechanism of a Ni3Al-Based Single Crystal Superalloy IC6SX

2013 ◽  
Vol 747-748 ◽  
pp. 797-803 ◽  
Author(s):  
Li Wu Jiang ◽  
Shu Suo Li ◽  
Mei Ling Wu ◽  
Ya Fang Han
Keyword(s):  
Single Crystal ◽  
Directional Solidification ◽  
Processing Parameters ◽  
Growth Direction ◽  
Selection Method ◽  
Single Crystal Superalloy ◽  
Competitive Growth ◽  
Deviation Angle ◽  
Spiral Grain ◽  
Competition Mechanism

The grain competitive growth and elimination during the directional solidification of a Ni3Al-base single crystal superalloy IC6SX prepared by spiral grain selection method was studied systematically. The experimental results revealed that there were 5 kinds of mechanism during the grain competitive growth and elimination. The grains with preferred growth direction and smaller deviation angle to growth direction have stronger competitiveness, and the mutual thwarting of dendrites played an important role in the processing of grains competitive growth. The results can explain the competitive growth mechanism during the directional solidification and can be used to optimize processing parameters to lay an important foundation for improving preparation processes of single crystal superalloys.

scholarly journals Fabrication of a Micron-Scale Three-Dimensional Single Crystal Diamond Channel Using a Micro-Jet Water-Assisted Laser

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3006
Author(s):  
Qiang Wei ◽  
Xiaofan Zhang ◽  
Fang Lin ◽  
Ruozheng Wang ◽  
Genqiang Chen ◽  
...  
Keyword(s):  
Single Crystal ◽  
Cross Sections ◽  
Microwave Plasma ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Optical Microscope ◽  
Epitaxial Lateral Overgrowth ◽  
Plasma Chemical Vapor Deposition ◽  
Lateral Overgrowth ◽  
Single Crystal Diamond

Two types of a trench with conventional vertical and new reverse-V-shaped cross-sections were fabricated on single crystal diamond (SCD) substrate using a micro-jet water-assisted laser. In addition, a microwave plasma chemical vapor deposition device was used to produce multiple micrometer-sized channels using the epitaxial lateral overgrowth technique. Raman and SEM methods were applied to analyze both types of growth layer characterization. The hollowness of the microchannels was measured using an optical microscope. According to the findings, the epitaxial lateral overgrowth layer of the novel reverse-V-shaped trench produced improved SCD surface morphology and crystal quality.

Formation Mechanism of Low Angle Boundary of DD6 Single Crystal Superalloy Blades

2012 ◽  
Vol 535-537 ◽  
pp. 1019-1022
Author(s):  
Z.X. Shi ◽  
J.R. Li ◽  
Shi Zhong Liu ◽  
J.Q. Zhao
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Single Crystal ◽  
Formation Mechanism ◽  
Selection Process ◽  
Optical Microscope ◽  
Single Crystal Superalloy ◽  
Competitive Growth ◽  
Solidification Condition ◽  
Scanning Electron

The specimens were machined from DD6 single crystal superalloy blades with low angle boundary. The misorientation of LAB was measured with EBSD technique in scanning electron microscope. The microstructures of specimens with LAB were examined in optical microscope and scanning electron microscope. The formation mechanism of low angle boundary of DD6 single crystal superalloy blades was investigated. The results showed that he formation of LAB which is caused by the deviating orientation from ideal [001] and the angle between the crystal orientation and shell is crystal selection process acted by dendrite competitive growth rule. Part of dendrites have changed their growth orientation a little to the decreasing [001] orientation departure angle because of solidification condition fluctuating during dendrites branching process. The LAB is the obvious interface between the deforming dendrites and their surrounding dendrites.

Influence of Withdrawal Rate on Tensile and Stress Rupture Properties of the Single Crystal Superalloy DD9

2013 ◽  
Vol 747-748 ◽  
pp. 625-628 ◽  
Author(s):  
Z.X. Shi ◽  
J.R. Li ◽  
Shi Zhong Liu
Keyword(s):  
Single Crystal ◽  
Rupture Life ◽  
Stress Rupture ◽  
Single Crystal Superalloy ◽  
Withdrawal Rate ◽  
Stress Rupture Life ◽  
The Third ◽  
Stress Orientation ◽  
Stress Rupture Properties ◽  
Rupture Properties

The third generation single crystal superalloy DD9 was processed with different withdrawal rates and the effect of withdrawal rate on the tensile and stress rupture properties of the alloy was investigated. The relation between the mechanical properties and microstructure of the alloy with different withdrawal rates was discussed. The results showed that the withdrawal rate had a little effect on the tensile properties at 25 of the alloy. The tensile strength at 980 and stress rupture life at 1120/140MPa of DD9 alloy all increased with the increasing of withdrawal rate. The γ precipitates of specimen tensile at 25 had a little extension in the stress orientation. The extension of γ precipitates in the stress orientation at 980 was much more than that at 25. The vertical γ matrix at 980 became thinner and horizontal γ matrix became thicker slightly. The γ precipitates of those had rafted in a direction transverse to the applied stress.

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