The Influence of the Cooling Bores on Crystal Orientation and Lattice Parameter in Single-Crystalline Cored Turbine Blades

The areas located near the cooling bores of single-crystalline cored turbine blades made of nickel-based CMSX-4 superalloy were studied. The blades were solidified by the vertical Bridgman technique in the industrial ALD furnace. Longitudinal sections of the blades were studied by Scanning Electron Microscopy, X-ray diffraction topography, X-ray diffraction measurements of the γ′-phase lattice parameter a, and the α angle of the primary crystal orientation. The local changes in α were analyzed in relation to the changes of the dendrite’s growth direction near the cooling bores. It was found that in the area approximately 3 ÷ 4 mm wide around the cooling bores, changes of α and a, both in the blade root and in the airfoil occurred. The local temperature distribution near the cooling bores formed a curved macroscopic solidification front, which caused changes in the chemical composition and, consequently, changes in the a value in a range of 0.002 Å to 0.014 Å. The mechanism of alloying elements segregation by tips of the dendrites on the bent solidification front was proposed. The multi-scale analysis that allows determining a relation between processes proceed both on a millimeter-scale and a micrometric and nanometric scale, was applied in the studies.

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The Influence of the Cooling Bores on the Dendritic Structure and Crystal Orientation in Single-Crystalline Cored CMSX-4 Turbine Blades

Materials ◽

10.3390/ma14143966 ◽

2021 ◽

Vol 14 (14) ◽

pp. 3966

Author(s):

Jacek Krawczyk ◽

Włodzimierz Bogdanowicz

Keyword(s):

Crystal Orientation ◽

Turbine Blades ◽

Dendritic Structure ◽

X Ray Diffraction ◽

Vertical Temperature ◽

Single Crystalline ◽

X Ray ◽

Vertical Bridgman ◽

The Relationship

Single-crystalline cored CMSX-4 blades obtained at a withdrawal rate of 3 mm/min by the vertical Bridgman method were analyzed. The dendritic structure and crystal orientation near the cooling bores of the blades were studied through Scanning Electron Microscopy, the X-ray diffraction measurements of α and β angular components of the primary crystal orientation, and the γ angular component of the secondary crystal orientation. Additionally, the primary arm spacing (PAS) was studied in areas near and far from the cooling bores. It was found that in the area approximately 3–4 mm wide around the cooling bores, changes occurred in the α, β, and γ angles, as well as in the PAS. The PAS determined for the transverse section of the root and the linear primary arm spacing (LPAS) determined for the longitudinal sections, as well as their relationship, have been defined for the areas located near the cooling bores and those at a distance from them. The vertical temperature gradient of 29.5 K/cm was estimated in the root areas located near the cooling bores based on the PAS values. The value of this gradient was significantly higher compared to the growth chamber operating gradient of 16 K/cm. The two-scale analysis applied in this study allowed for the determination of the relationship between the process of dendrite array creation proceeding on a millimeter scale, which is associated with the local changes in crystal orientation near the cooling bores, and that which proceeds on a scale of tens of millimeters, associated with the changes in crystal orientation in the whole blade cast.

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The Low-Angle Boundaries Misorientation and Lattice Parameter Changes in the Root of Single-Crystalline CMSX-4 Superalloy Blades

Materials ◽

10.3390/ma14185194 ◽

2021 ◽

Vol 14 (18) ◽

pp. 5194

Author(s):

Robert Paszkowski ◽

Włodzimierz Bogdanowicz ◽

Dariusz Szeliga

Keyword(s):

Electron Microscopy ◽

Turbine Blades ◽

Diffraction Method ◽

Lattice Parameter ◽

Internal Stresses ◽

X Ray Diffraction ◽

Single Crystalline ◽

X Ray ◽

The Relationship ◽

Scanning Electron

The relationship between the angles of misorientation of macroscopic low-angle boundaries (LABs) and changes in the lattice parameter of the γ′-phase around the LABs in the root of single-crystalline (SX) turbine blades made of CMSX-4 superalloy were studied. The blades with an axial orientation of the [001] type were solidified using an industrial Bridgman furnace with a 3 mm/min withdrawal rate. X-ray diffraction topography, the EFG Ω-scan X-ray diffraction method, scanning electron microscopy, and Laue diffraction were used to study the thin lamellar samples with a thickness of 0.5 mm and orientation of the surface perpendicular to the [001] direction. It is found that in the areas with a width of a few millimetres around LABs, decreases in the lattice parameter of the γ′-phase occur. These lattice parameter changes are related to the internal stresses of the γ′-phase caused by local changes in the concentration of alloying elements and/or to the dendrite bending near the LABs. X-ray topography used on two surfaces of thin lamellar samples coupled with the lattice parameter measurements of the γ′-phase near the LAB allows separating the misorientation component of LAB diffraction contrast from the component and visualising the internal stresses of the γ′-phase.

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Heterogeneity of the Dendrite Array Created in the Root of Cored SX Turbine Blades during Initial Stage of Crystallization

Materials ◽

10.3390/ma14010080 ◽

2020 ◽

Vol 14 (1) ◽

pp. 80

Author(s):

Robert Paszkowski ◽

Jacek Krawczyk ◽

Włodzimierz Bogdanowicz ◽

Dariusz Szeliga ◽

Jan Sieniawski

Keyword(s):

Transverse Section ◽

Turbine Blades ◽

Lateral Growth ◽

X Ray Diffraction ◽

Dendrite Branching ◽

X Ray ◽

Initial Stage ◽

Vertical Bridgman ◽

Lateral Dendrite ◽

Root Connection

The roots of cored single-crystalline turbine blades made of a nickel-based CMSX-4 superalloy were studied. The casts were solidified by the vertical Bridgman method in an industrial ALD furnace using the spiral selector and selector continuer situated asymmetrically in the blade root transverse section. Scanning electron microscopy, the Laue diffraction and X-ray diffraction topography were used to visualize the dendrite array and the local crystal misorientation of the roots. It has been stated that heterogeneity of the dendrite array and creation of low-angle boundaries (LABs) are mostly related to the lateral dendrite branching and rapid growth of the secondary and tertiary dendrites near the surface of the continuer–root connection. These processes have an unsteady character. Additionally, the influence of the mould walls on the dendrite array heterogeneity was studied. The processes of the lateral growth of the secondary dendrites and competitive longitudinal growth of the tertiary dendrites are discussed and a method of reducing the heterogeneity of the root dendrite array is proposed.

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Primary Crystal Orientation of the Thin-Walled Area of Single-Crystalline Turbine Blade Airfoils

Materials ◽

10.3390/ma12172699 ◽

2019 ◽

Vol 12 (17) ◽

pp. 2699 ◽

Cited By ~ 6

Author(s):

Włodzimierz Bogdanowicz ◽

Jacek Krawczyk ◽

Robert Paszkowski ◽

Jan Sieniawski

Keyword(s):

Crystal Orientation ◽

Primary Dendrite ◽

Turbine Blades ◽

Diffraction Method ◽

Crystallographic Direction ◽

Primary Crystal ◽

X Ray Diffraction ◽

Trailing Edge ◽

Single Crystalline ◽

Thin Walled

The thin-walled airfoil areas of as-cast single-crystalline turbine blades made of CMSX-4 superalloy were studied. The blades were produced by the industrial Bridgman technique at withdrawal rates of 2, 3 and 4 mm/min. The angle between the [001] crystallographic direction and blade axis, related to the primary orientation, was defined by the Ω-scan X-ray diffraction method at points on the camber line located near the tip of an airfoil and at points of a line located in parallel and near the trailing edge. Additionally, primary crystal orientation was determined by Laue diffraction at the selected points of an airfoil. The influence of mould wall inclination on the primary crystal orientation of the thin-walled areas is discussed. The effect of change in the [001] crystallographic direction, named as “force directing”, was considered with regard to the arrangement of primary dendrite arms in relation to the trailing edge and the camber line. It was stated that when the distance between the mould walls is less than the critical value of about 1.5 mm the “force directing” increases as the distance between the walls of the mould decreases. The effect may be controlled by selecting an appropriate secondary orientation using a seed crystal in the blade production process. The model of dendrite interaction with the mould walls, including bending and “deflection”, was proposed.

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Control of Crystallographic Orientation and Grain Refinement in Bi2Te3-Based Thermoelectric Semiconductors by Applying High Pressure Torsion

Materials Science Forum ◽

10.4028/www.scientific.net/msf.584-586.1006 ◽

2008 ◽

Vol 584-586 ◽

pp. 1006-1011 ◽

Cited By ~ 10

Author(s):

Maki Ashida ◽

Takashi Hamachiyo ◽

Kazuhiro Hasezaki ◽

Hirotaka Matsunoshita ◽

Masaaki Kai ◽

...

Keyword(s):

High Pressure ◽

Crystal Orientation ◽

High Pressure Torsion ◽

Crystallographic Structure ◽

Nominal Composition ◽

X Ray Diffraction ◽

X Ray ◽

Refined Microstructure ◽

Vertical Bridgman ◽

P Type

Prepared were p-type Bi2Te3-based thermoelectric semiconductors, having a grain-refined microstructure and a preferred orientation of anisotropic crystallographic structure. Disks with a nominal composition Bi0.5Sb1.5Te3.0 were cut from an ingot grown by the vertical Bridgman method (VBM) and deformed at 473 K under a pressure of 6.0 GPa by high pressure torsion (HPT). The crystal orientation was characterized with X-ray diffraction. The microstructures were characterized by using optical microscopy and scanning electron microscopy. It was found that the HPT disks had a fine and preferentially oriented grain compared to that of the VBM disks. Further, the power factor of the HPT disks was about twice as large as that of the VBM disks. These results indicate that HPT is effective for improving the thermoelectric properties of Bi2Te3-based thermoelectric semiconductors.

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Analysis of CMSX-4 Single-Crystalline Turbine Blades Root by Electron and X-Ray Diffraction Methods

Acta Physica Polonica A ◽

10.12693/aphyspola.130.1104 ◽

2016 ◽

Vol 130 (4) ◽

pp. 1104-1106

Author(s):

J. Krawczyk ◽

M. Zubko ◽

W. Bogdanowicz ◽

A. Tondos ◽

J. Sieniawski

Keyword(s):

Turbine Blades ◽

X Ray Diffraction ◽

Single Crystalline ◽

X Ray

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Defect Creation in the Root of Single-Crystalline Turbine Blades Made of Ni-Based Superalloy

Materials ◽

10.3390/ma12060870 ◽

2019 ◽

Vol 12 (6) ◽

pp. 870 ◽

Cited By ~ 3

Author(s):

Jacek Krawczyk ◽

Robert Paszkowski ◽

Włodzimierz Bogdanowicz ◽

Aneta Hanc-Kuczkowska ◽

Jan Sieniawski ◽

...

Keyword(s):

Turbine Blades ◽

Lateral Growth ◽

X Ray Diffraction ◽

Single Crystalline ◽

X Ray ◽

Positron Annihilation Lifetime ◽

The Creation ◽

Misorientation Angles ◽

Axial Growth ◽

Root Connection

An analysis of the defects in the vicinity of the selector–root connection plane occurring during the creation of single-crystalline turbine blades made of CMSX-6 Ni-based superalloy was performed. X-ray diffraction topography, scanning electron microscopy, and positron annihilation lifetime spectroscopy were used. Comparing the area of undisturbed axial growth of dendrites to the area of lateral growth concluded that the low-angle boundaries-like (LAB-like) defects were created in the root as a result of unsteady-state lateral growth of some secondary dendrite arms in layers of the root located directly at the selector–root connection plane. Additional macroscopic low-angle boundaries (LABs) with higher misorientation angles were created as a result of concave curvatures of liquidus isotherm in platform-like regions near selector–root connections. Two kinds of vacancy-type defects, mono-vacancies and vacancy clusters, were determined in relation to the LABs and LAB-like defects. Only mono-vacancies appeared in the areas of undisturbed axial growth. Reasons for the creation of macroscopic LABs and LAB-like defects, and their relationships with vacancy-type defects were discussed.

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Variation of Crystal Orientation and Dendrite Array Generated in the Root of SX Turbine Blades

Materials ◽

10.3390/ma12244126 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4126 ◽

Cited By ~ 2

Author(s):

Włodzimierz Bogdanowicz ◽

Jacek Krawczyk ◽

Robert Paszkowski ◽

Jan Sieniawski

Keyword(s):

Crystal Orientation ◽

Crystallization Front ◽

Turbine Blades ◽

Crystallographic Direction ◽

Lateral Growth ◽

Primary Crystal ◽

X Ray Diffraction ◽

Bridgman Technique ◽

X Ray ◽

Complex Wave

The variation of the crystal orientation and the dendrite array generated in the root of the single-crystalline (SX) turbine blades made of CMSX-4 superalloy were studied. The blades with an axial orientation of the [001] type were solidified by the industrial Bridgman technique using a spiral selector at a withdrawal rate of 3 mm/min. The analysis of the crystal orientation and dendrite arrangement was carried out using scanning electron microscopy, X-ray diffraction topography, and Laue diffraction. It was found that the lateral growth of such secondary dendrite arms, which are defined as “leading” and grow in the root at first, is related to the rotation of their crystal lattice, which is the reason for creation of the low-angle boundary (LAB) type defects. The primary crystal orientation of the selector extension (SE) area determines the areas and directions of the lateral growth of the leading arms. Additionally, it was found that in the SE areas of the root, near the connection with the selector, the spatial distribution of the [001]γ′ crystallographic direction has a complex wave-like character and may be related to the shape of the crystallization front.

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Photoconductivity of the Single Crystals Pb4Ga4GeS12 and Pb4Ga4GeSe12

Proceedings ◽

10.3390/proceedings2020062004 ◽

2020 ◽

Vol 62 (1) ◽

pp. 4

Author(s):

Hadj Bellagra ◽

Oksana Nyhmatullina ◽

Yuri Kogut ◽

Halyna Myronchuk ◽

Lyudmyla Piskach

Keyword(s):

Ternary Systems ◽

Semiconductor Materials ◽

Tetragonal Symmetry ◽

Bandgap Energy ◽

Experimental Measurements ◽

X Ray Diffraction ◽

X Ray ◽

Vertical Bridgman ◽

Symmetry Space ◽

Symmetry Space Group

Quaternary semiconductor materials of the Pb4Ga4GeS(Se)12 composition have attracted the attention of researchers due to their possible use as active elements of optoelectronics and nonlinear optics. The Pb4Ga4GeS(Se)12 phases belong to the solid solution ranges of the Pb3Ga2GeS(Se)8 compounds which form in the quasi-ternary systems PbS(Se)−Ga2S(Se)3−GeS(Se)2 at the cross of the PbGa2S(Se)4−Pb2GeS(Se)4 and PbS(Se)−PbGa2GeS(Se)6 sections. The quaternary sulfide melts congruently at 943 K. The crystallization of the Pb4Ga4GeSe12 phase is associated with the ternary peritectic process Lp + PbSe ↔ PbGa2S4 + Pb3Ga2GeSe8 at 868 K. For the single crystal studies, Pb4Ga4GeS(Se)12 were pre-synthesized by co-melting high-purity elements. The X-ray diffraction results confirm that these compounds possess non-centrosymmetric crystal structure (tetragonal symmetry, space group P–421c). The crystals were grown by the vertical Bridgman method in a two-zone furnace. The starting composition was stoichiometric for Pb4Ga4GeS12, and the solution-melt method was used for the selenide Pb4Ga4GeSe12. The obtained value of the bandgap energy for the Pb4Ga4GeS12 and Pb4Ga4GeSe12 crystals is 1.86 and 2.28 eV, respectively. Experimental measurements of the spectral distribution of photoconductivity for the Pb4Ga4GeS12 and Pb4Ga4GeSe12 crystals exhibit the presence of two spectral maxima. The first lies in the region of 570 (2.17 eV) and 680 nm (1.82 eV), respectively, and matches the optical bandgap estimates well. The locations of the admixture maxima at about 1030 (1.20 eV) and 1340 nm (0.92 eV), respectively, agree satisfactorily with the calculated energy positions of the defects vs. and VSe.

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Growth of sillenite Bi12FeO20 single crystals: structural, thermal, optical, photocatalytic features and first principle calculations

Scientific Reports ◽

10.1038/s41598-020-78598-3 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Durga Sankar Vavilapalli ◽

Ambrose A. Melvin ◽

F. Bellarmine ◽

Ramanjaneyulu Mannam ◽

Srihari Velaga ◽

...

Keyword(s):

Single Crystal ◽

Single Crystals ◽

Photoelectron Spectroscopy ◽

Diffraction Method ◽

Lattice Parameter ◽

First Principle ◽

X Ray Diffraction ◽

X Ray ◽

First Principle Calculations ◽

Photodegradation Efficiency

AbstractIdeal sillenite type Bi12FeO20 (BFO) micron sized single crystals have been successfully grown via inexpensive hydrothermal method. The refined single crystal X-ray diffraction data reveals cubic Bi12FeO20 structure with single crystal parameters. Occurrence of rare Fe4+ state is identified via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The lattice parameter (a) and corresponding molar volume (Vm) of Bi12FeO20 have been measured in the temperature range of 30–700 °C by the X-ray diffraction method. The thermal expansion coefficient (α) 3.93 × 10–5 K−1 was calculated from the measured values of the parameters. Electronic structure and density of states are investigated by first principle calculations. Photoelectrochemical measurements on single crystals with bandgap of 2 eV reveal significant photo response. The photoactivity of as grown crystals were further investigated by degrading organic effluents such as Methylene blue (MB) and Congo red (CR) under natural sunlight. BFO showed photodegradation efficiency about 74.23% and 32.10% for degrading MB and CR respectively. Interesting morphology and microstructure of pointed spearhead like BFO crystals provide a new insight in designing and synthesizing multifunctional single crystals.

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