scholarly journals Grain Selection in a High-Efficiency 2D Grain Selector During Casting of Single-Crystal Superalloys

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 789 ◽  
Author(s):  
Xintao Zhu ◽  
Fu Wang ◽  
Dexin Ma ◽  
Andreas Bührig-Polaczek
Keyword(s):  
Single Crystal ◽  
Optical Microscopy ◽  
High Efficiency ◽  
Two Dimensional ◽  
Competitive Growth ◽  
Electron Backscattered Diffraction ◽  
Single Grain ◽  
Eccentric Distance

Using electron backscattered diffraction techniques (EBSD) and optical microscopy (OM), the grain selection and competitive growth in a new-designed high-efficiency two-dimensional (2D) selector during solidification of Ni-based single-crystal (SX) superalloys have been investigated with emphasis on the geometry of the selector part in this article. It is found that the efficiency of the grain selector depends greatly on the thickness and eccentric distance of the selector part. When the thickness is smaller than 3 mm, a single grain can be selected. After reducing this value, the grain selector becomes more effective. When the eccentric distance is larger than 8 mm, one grain can be selected. As the eccentric distance increases, the selector’s efficiency is optimized. Recommendations for optimizing the geometry of the selector part are provided.

scholarly journals Using a Three-Dimensional Reduction Method in the High-Efficiency Grain Selector and Corresponding Grain Selection Mechanism

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1781
Author(s):  
Xintao Zhu ◽  
Fu Wang ◽  
Shuaipeng Zhang ◽  
Tobias Wittenzellner ◽  
Jessica Frieß ◽  
...  
Keyword(s):  
Single Crystal ◽  
High Efficiency ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Two Dimensional ◽  
Selection Mechanism ◽  
Dimensional Reduction Method ◽  
Optimization Parameters ◽  
Dimensional Coupling

In the development of a high-efficiency grain selector, the spiral selectors are widely used in Ni-based single crystal (SX) superalloys casting to produce single crystal turbine blades. For the complex three-dimensional structure of the spiral, a 2D grain selector was designed to investigate in this paper. As a result, the parameters of two-dimensional grain selection bond and the corresponding grain selection mechanism were established, and the three-dimensional grain selection bond was designed again by means of two-dimensional coupling optimization parameters.

scholarly journals Development of a High-Efficiency Z-Form Selector for Single Crystal Blades and Corresponding Grain Selection Mechanism

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 780 ◽  
Author(s):  
Xintao Zhu ◽  
Fu Wang ◽  
Dexin Ma ◽  
Andreas Bührig-Polaczek
Keyword(s):  
Single Crystal ◽  
High Efficiency ◽  
Geometrical Structure ◽  
Turbine Blades ◽  
Grain Structure ◽  
Two Dimensional ◽  
Coating Properties ◽  
Turbine Engine ◽  
Research Material ◽  
Super Alloy

Single crystal (SX) is widely used in modern turbine blades to improve the creep fracture, fatigue, oxidation, and coating properties of the turbine, so that the turbine engine has excellent performance and durability. In this paper, the single crystal super alloy MM247LC is used as the research material. The evolution of grain structure in a two-dimensional grain selector was studied by directional experiments, and the mechanism of grain selection in the two-dimensional channel during directional solidification was clarified. In order to optimize the production process of single crystal turbine blades, the effects of the geometrical structure of a Z-type separator (i.e., wire diameter and take-off angle) on the crystal orientation, microstructure, and grain efficiency of blades were discussed.

scholarly journals Grain Orientation Optimization of Two-Dimensional Grain Selector during Directional Solidification of Ni-Based Superalloys

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1121 ◽  
Author(s):  
Xintao Zhu ◽  
Qiang Yang ◽  
Fu Wang ◽  
Dexin Ma
Keyword(s):  
Single Crystal ◽  
Grain Orientation ◽  
Selection Method ◽  
Two Dimensional ◽  
Deviation Angle ◽  
Electron Backscattered Diffraction ◽  
High Quality ◽  
Orientation Deviation ◽  
Superalloy Single Crystal ◽  
Orientation Optimization

The grain selection method is widely used in industry to produce Ni-based single crystal superalloys. A Z-form two-dimensional (2D) grain selector was designed to obtain high-quality single crystals. To control grain orientation deviation, one of the most important defects of the single crystal superalloys in casting, Z-form 2D grain selectors with different take-off angle were investigated in this study. The MM247LC superalloy single crystal samples were obtained by the Bridgman method modified by the Z-form grain selectors in this study. The Electron Backscattered Diffraction (EBSD) and the Optical Microscopy (OM) were used to observe and measure the grain selection growth and the microstructural evolution and orientation of the single crystal were also discussed. The results show that a Z-form 2D grain selector with an appropriate take-off angle can significantly reduce the deviation of the grain orientation. A single crystal superalloy with a deviation angle less than 6° can be obtained effectively when the take-off angle was 40°.

Dislocations, Ordering and Antiferromagnetic Domains in MnO

1970 ◽  
Vol 28 ◽  
pp. 522-523
Author(s):  
D. J. Barber ◽  
R. G. Evans
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Optical Microscopy ◽  
Defect Chemistry ◽  
Magnetic Structures ◽  
Optically Transparent ◽  
Magnetic Features ◽  
Antiferromagnetic Domains

Manganese (II) oxide, MnO, in common with CoO, NiO and FeO, possesses the NaCl structure and shows antiferromagnetism below its Neel point, Tn∼ 122 K. However, the defect chemistry of the four oxides is different and the magnetic structures are not identical. The non-stoichiometry in MnO2 small (∼2%) and below the Tn the spins lie in (111) planes. Previous work reported observations of magnetic features in CoO and NiO. The aim of our work was to find explanations for certain resonance results on antiferromagnetic MnO.Foils of single crystal MnO were prepared from shaped discs by dissolution in a mixture of HCl and HNO3. Optical microscopy revealed that the etch-pitted foils contained cruciform-shaped precipitates, often thick and proud of the surface but red-colored when optically transparent (MnO is green). Electron diffraction and probe microanalysis indicated that the precipitates were Mn2O3, in contrast with recent findings of Co3O4 in CoO.

scholarly journals Single crystal of two-dimensional mixed-halide copper-based perovskites with reversible thermochromism

2021 ◽  
Author(s):  
Amr Elattar ◽  
Hiroo Suzuki ◽  
Ryuji Mishima ◽  
Kodai Nakao ◽  
Hiromi Ota ◽  
...  
Keyword(s):  
Single Crystal ◽  
Band Gaps ◽  
Two Dimensional ◽  
Facile Synthesis ◽  
Reversible Thermochromism

Facile synthesis of single crystal of two-dimensional mixed-halide copper-based perovskites with tunable band gaps and their capability of exfoliation and reversible thermochromism.

Study of the Machining Principle and Influencing of ELID Grinding on SiC

2012 ◽  
Vol 217-219 ◽  
pp. 1642-1645
Author(s):  
Qiang Xiao
Keyword(s):  
Single Crystal ◽  
High Efficiency ◽  
Machining Time ◽  
Elid Grinding

The hardness of SiC single crystal is very closer to that of diamond, which makes it greatly difficult to process SiC single crystal. It is usually machined by lapping, but this technique requires a long machining time, resulting in low productivity, So we examine the possibility of ELID grinding in SiC single crystal. Results show that with the use of ELID, mirror surfaces can be achieved with high efficiency.

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