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

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4126 ◽  
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.

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

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2699 ◽  
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.

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

Materials ◽  
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.

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

Materials ◽  
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.

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

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3842
Author(s):  
Jacek Krawczyk ◽  
Włodzimierz Bogdanowicz ◽  
Jan Sieniawski
Keyword(s):  
Solidification Front ◽  
Crystal Orientation ◽  
Turbine Blades ◽  
Lattice Parameter ◽  
Growth Direction ◽  
X Ray Diffraction ◽  
Single Crystalline ◽  
X Ray ◽  
Vertical Bridgman ◽  
Α Angle

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.

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

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 870 ◽  
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.

Structural changes in titanium dioxide nanocrystals during plastic deformation

2005 ◽  
Vol 38 (5) ◽  
pp. 749-756 ◽  
Author(s):  
Ulrich Gesenhues
Keyword(s):  
Structural Changes ◽  
Crystal Size ◽  
Lower Layer ◽  
High Energy ◽  
Primary Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hall Method ◽  
Means Of Transmission

The polygonization of 200 nm rutile crystals during dry ball-milling at 10gwas monitored in detail by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). The TEM results showed how to modify the Williamson–Hall method for a successful evaluation of crystal size and microstrain from XRD profiles. Macrostrain development was determined from the minute shift of the most intense reflection. In addition, changes in pycnometrical density were monitored. Accordingly, the primary crystal is disintegrated during milling into a mosaic of 12–35 nm pieces where the grain boundaries induce up to 1.2% microstrain in a lower layer of 6 nm thickness. Macrostrain in the interior of the crystals rises to 0.03%. The pycnometrical density, reflecting the packing density of atoms in the grain boundary, decreases steadily by 1.1%. The results bear relevance to our understanding of plastic flow and the mechanism of phase transitions of metal oxides during high-energy milling.

Synthesis of Supergrowth VACNTs and Nanostructured ZnO by Immerse Method

2011 ◽  
Vol 312-315 ◽  
pp. 1044-1048
Author(s):  
Salina Muhamad ◽  
Abu Bakar Suriani ◽  
Mohamad Zainizan Sahdan ◽  
Anuar Ahmad ◽  
Yosri M. Siran ◽  
...  
Keyword(s):  
Crystal Orientation ◽  
Zinc Nitrate ◽  
Zinc Nitrate Hexahydrate ◽  
Nitrate Hexahydrate ◽  
X Ray Diffraction ◽  
Vertically Aligned Carbon Nanotubes ◽  
X Ray ◽  
Aligned Carbon Nanotubes ◽  
Vertically Aligned ◽  
Physical Changes

In this paper, the study of supergrowth VACNTs after being immersed in zinc oxide solution were presented. Vertically aligned carbon nanotubes (VACNTs) were first deposited on silicon with the orientation of [1 0 0] before being immersed in an aqueous solution of zinc nitrate hexahydrate and hexamethylenetetramine. Physical changes have been observed by scanning electron microscopy, SEM in the VACNTs, where the significant expansion of length of up to almost 0.8 mm was achieved after the immersion of 4.5 hr. The supergrowth of VACNTs was observed and analyzed by energy dispersive x-ray spectroscopy, EDX to substantiate the incorporation of CNTs and ZnO of the sample. Raman spectroscopy and x-ray diffraction, XRD were used to inspect the crystal orientation to support our findings.

scholarly journals Microscopic Stress and Strain Evolved in a Twinning-Induced Plasticity Fe-Mn-C Steel

2014 ◽  
Vol 996 ◽  
pp. 135-140
Author(s):  
Shigeru Suzuki ◽  
Shigeo Sato ◽  
Koji Hotta ◽  
Eui Pyo Kwon ◽  
Shun Fujieda ◽  
...  
Keyword(s):  
Strain Distribution ◽  
Crystal Orientation ◽  
Fem Simulation ◽  
Tensile Loading ◽  
Stress And Strain ◽  
X Ray Diffraction ◽  
Principal Stresses ◽  
Orientation Data ◽  
Tensile Direction ◽  
X Ray

White X-ray diffraction with micro-beam synchrotron radiation was used to analyze microscopic stress evolved in coarse grains of a twinning-induced plasticity Fe-Mn-C steel under tensile loading. In addition, electron backscatter diffraction (EBSD) was used to determine the crystal orientation of grains in the polycrystalline Fe-Mn-C steel. Based on these orientation data, the stress and strain distribution in the microstructure of the steel under tensile loading was estimated using FEM simulation where the elastic anisotropy or the crystal orientation dependence of the elasticity was taken into account. The FEM simulation showed that the strain distribution in the microstructure depends on the crystal orientation of each grain. The stress analysis by the white X-ray diffraction indicated that the direction of the maximum principal stresses at measured points in the steel under tensile loading are mostly oriented toward the tensile direction. This is qualitatively consistent with the results of by the FEM simulation, although absolute values of the principal stresses may contain the effect of heterogeneous plastic deformation on the stress distribution.

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