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°.

Preparation of single-crystal metal substrates for the growth of high-quality two-dimensional materials

2021 ◽  
Vol 8 (1) ◽  
pp. 182-200
Author(s):  
Yanglizhi Li ◽  
Luzhao Sun ◽  
Haiyang Liu ◽  
Yuechen Wang ◽  
Zhongfan Liu
Keyword(s):  
Single Crystal ◽  
2D Materials ◽  
Controlled Growth ◽  
Two Dimensional ◽  
High Quality ◽  
Metal Substrates ◽  
Recent Advances ◽  
Two Dimensional Materials

Recent advances on preparing single-crystal metals and their crucial roles in controlled growth of high-quality 2D materials are reviewed.

Two-dimensional (PEA)2PbBr4 perovskite single crystals for a high performance UV-detector

2019 ◽  
Vol 7 (6) ◽  
pp. 1584-1591 ◽  
Author(s):  
Yunxia Zhang ◽  
Yucheng Liu ◽  
Zhuo Xu ◽  
Haochen Ye ◽  
Qingxian Li ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
High Performance ◽  
Two Dimensional ◽  
Uv Detector ◽  
High Quality ◽  
Photo Response ◽  
Response Performance

A centimeter-sized high-quality two-dimensional (PEA)2PbBr4 single crystal was prepared, which exhibited superior UV photo-response performance.

Ion-beam synthesis of epitaxial Au nanocrystals in MgO

2004 ◽  
Vol 19 (5) ◽  
pp. 1311-1314 ◽  
Author(s):  
S. Thevuthasan ◽  
V. Shutthanandan ◽  
C.M. Wang ◽  
W.J. Weber ◽  
W. Jiang ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Single Crystal ◽  
Ion Beam ◽  
Three Dimensional ◽  
Subsequent Annealing ◽  
Two Dimensional ◽  
Epitaxial Relationship ◽  
High Quality ◽  
Au Nanoclusters ◽  
Au Clusters

The formation of Au nanoclusters in MgO using ion implantation and subsequent annealing was investigated. Approximately 1200 and 1400 Au2+ ions/nm2 were implanted in MgO(100) substrates at 300 and 975 K, respectively. Subsequent annealing in air for 10 h at 1275 K promoted the formation of Au nanostructures in MgO. The sample implanted at 300 K showed severe radiation damage. In addition, two-dimensional plateletlike structures with possible composition of Au and MgO were formed during implantation in the sample that was implanted at 300 K. In contrast, Au implantation at 975 K promoted the nucleation of Au nanostructures during implantation. Subsequent annealing of both samples show three-dimensional clusters in MgO. However, the 975 K implanted sample shows clean, high-quality, single-crystal Au clusters that have an epitaxial relationship to MgO(100).

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 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 High performance self-powered photodetector based on 1D Te-2D WS2 mixed-dimensional heterostructure

2021 ◽  
Author(s):  
Lixiang Han ◽  
Mengmeng Yang ◽  
Peiting Wen ◽  
Wei Gao ◽  
nengjie huo ◽  
...  
Keyword(s):  
High Performance ◽  
Van Der Waals ◽  
Sharp Interface ◽  
Two Dimensional ◽  
High Quality ◽  
One Dimensional ◽  
Self Powered

One dimensional (1D)-two dimensional (2D) van der Waals (vdWs) mixed-dimensional heterostructures with advantages of atomically sharp interface, high quality and good compatibility have attracted tremendous attention in recent years. The...

scholarly journals Investigation of the Heteroepitaxial Process Optimization of Ge Layers on Si (001) by RPCVD

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 928
Author(s):  
Yong Du ◽  
Zhenzhen Kong ◽  
Muhammet Toprak ◽  
Guilei Wang ◽  
Yuanhao Miao ◽  
...  
Keyword(s):  
High Temperature ◽  
Buffer Layer ◽  
Layer Thickness ◽  
Growth Temperature ◽  
Crystalline Quality ◽  
Initial Growth ◽  
Two Dimensional ◽  
High Quality ◽  
Reduced Pressure

This work presents the growth of high-quality Ge epilayers on Si (001) substrates using a reduced pressure chemical vapor deposition (RPCVD) chamber. Based on the initial nucleation, a low temperature high temperature (LT-HT) two-step approach, we systematically investigate the nucleation time and surface topography, influence of a LT-Ge buffer layer thickness, a HT-Ge growth temperature, layer thickness, and high temperature thermal treatment on the morphological and crystalline quality of the Ge epilayers. It is also a unique study in the initial growth of Ge epitaxy; the start point of the experiments includes Stranski–Krastanov mode in which the Ge wet layer is initially formed and later the growth is developed to form nuclides. Afterwards, a two-dimensional Ge layer is formed from the coalescing of the nuclides. The evolution of the strain from the beginning stage of the growth up to the full Ge layer has been investigated. Material characterization results show that Ge epilayer with 400 nm LT-Ge buffer layer features at least the root mean square (RMS) value and it’s threading dislocation density (TDD) decreases by a factor of 2. In view of the 400 nm LT-Ge buffer layer, the 1000 nm Ge epilayer with HT-Ge growth temperature of 650 °C showed the best material quality, which is conducive to the merging of the crystals into a connected structure eventually forming a continuous and two-dimensional film. After increasing the thickness of Ge layer from 900 nm to 2000 nm, Ge surface roughness decreased first and then increased slowly (the RMS value for 1400 nm Ge layer was 0.81 nm). Finally, a high-temperature annealing process was carried out and high-quality Ge layer was obtained (TDD=2.78 × 107 cm−2). In addition, room temperature strong photoluminescence (PL) peak intensity and narrow full width at half maximum (11 meV) spectra further confirm the high crystalline quality of the Ge layer manufactured by this optimized process. This work highlights the inducing, increasing, and relaxing of the strain in the Ge buffer and the signature of the defect formation.

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.

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