In the work, ceramics (zirconium silicate, aluminosilicates, mullite, zirconium dioxide), waxes, and binders used in investment casting of nickel-based superalloys have been characterized. Additionally, methodology of wax model pattern and ceramic molds for investment casting process have been discussed. The manufacturing methods (Bridgman, liquid metal cooling (LMC), gas cooling casting (GCC)) of single crystal and directionally solidified (DS) castings (mainly of aircraft engine and gas turbine blades) from nickel-based superalloys were presented. Moreover, the geometry of starter and selector in single crystal (SC) castings has been characterized. In the work, chemical composition of nickel-based superalloys (DS and SC), heat treatment technology, and test methods (macro-and microstructure, mechanical properties, crystalline perfection by Laue method, EBSD, and diffractometry) of nickel-based superalloys casting were shown and the principles of modeling the process of directional solidification (nucleation and grain growth) by finite element method (FEM) method has been described.

Characterization of structure defects in turbine blades is the basis for determination of the overall crystalline perfections. This work presents the possibilities of identifying casting defects by combining different X-ray diffraction techniques. The investigation was conducted on samples prepared from as-cast turbine blades airfoil and tips. It was found that X-ray topograms revealed dendritic structure and macro strain areas. The defects areas which have appeared on topograms were also investigated by X-ray diffraction mapping technique by EFG diffractometer. Additionally, the X-ray investigation was complemented by macro SEM images obtained by stitching several images of microstructure. The X-ray maps of misorientation angle and X-ray topograms revealed deviation between the γ’ direction and the blade axis and rotation of the primary dendrite arm around this axis.

Nickel-based single-crystal superalloys are widely used for production of high pressure turbine blades. The studied blades were obtained in an ALD Vacuum Technologies furnace by the Bridgman technique. Crystallization process was carried out with drawing rates of 3 mm/min and 5 mm/min. The dendrite microstructure based on the γ/γ’ phases and their defects was characterized using X-Ray topography, Laue diffraction, transmission electron microscopy. The defect structure samples were examined with the positron annihilation lifetime spectroscopy. It was found that crystal orientation, lattice parameter of γ’ phase and concentration of defects are correlated. The defect concentration increases in some areas which was the result of deviation of the primary dendrite arm from crystallization direction . Only one type of point defects was detected.

The article presents the comparison of two methods: classical X-ray topography and the modern automatic X-ray OD-EFG diffractometer. Both methods were applied to study the crystal orientation of turbine blades of single crystal nickel-based superalloys. The solidification of a hollow assembly structure for 5 various blades was carried out by the Bridgman method at the Research and Development Laboratory for Aerospace Materials at Rzeszow University of Technology using an ALD Vacuum Technologies vacuum furnace. Ceramic moulds made of Al2O3 were used. The alloy temperature during casting into the mould amounted to 1550°C. The specimens for Laue method tests were cut out from the blades at withdrawal rates of 1, 2, 3, 4, and 5 mm/min.

The paper attempts to determine the changes in the γ’ lattice orientation of aircraft engine turbine blades made of the CMSX-4 single crystal nickel superalloy. The solidification of a hollow assembly structure for 2 various blades was carried out by the Bridgman method at the Research and Development Laboratory for Aerospace Materials at Rzeszow University of Technology using an ALD Vacuum Technologies vacuum furnace. Ceramic moulds made of Al2O3 were used. The alloy temperature during casting into the mould amounted to 1550°C. The specimens for Laue method tests were cut out from the blades at withdrawal rates of 3 and 4 mm/min.

In the work the single-crystalline alloy CMSX-4 was studied. The main aim of the study was an attempt to find correlations between images of X-Ray topography, X-ray diffraction maps of lattice parameter and misorientation angle and Scanning Electron Microscopy (SEM) images obtained by back-scattered electron (BSE) technique. Topography images were obtained by Auleytner method with wide beam. Diffractometer provided by EFG company was used for obtaining orientation and lattice parameter maps. Material for research was produced in Research and Development Laboratory for Aerospace Materials of Rzeszów University of Technology. Casts were obtained in ALD furnace by the Bridgman technique. It was found that X-ray topograms were correlated with SEM images of microstructures as well as with orientation and lattice parameter maps. X-Ray topograms showed high contrast bands which corresponded to dendrite arms. There was a correlation between low angle boundary and lattice parameter map.

The aircraft engines turbine blades are manufactured from nickel-base superalloys and they are often in a single crystal form. This ensures the best high-temperature creep resistance as compared with blades of equiaxial grains microstructure and of columnar grains microstructure. Turbine blades were manufactured in an ALD Vacuum Technologies furnace. The study has examined structural perfection of single crystal blades obtained by Bridgeman method from CMSX-4 nickel superalloy at various withdrawal rates: 1, 2, 3, 4 and 5mm/min.

Electrochemical polarization characteristics of glow-discharge, high-temperature (520 degrees C) nitrided AISI 4140 type steel and Fe-Armco are presented in the paper. The potentiokinetic tests were carried out in acidified, 0.5M sulphate (pH = 4) solution containing 0.02M of chloride ions. A method of consecutive thinning of surfacial layers of the treated steel has been applied to determine the depth profiles of its pitting potentials.

The paper attempts to determine structural perfection of monocrystalline nickel superalloys using X-ray topography. Monocrystalline bars and turbine blades were manufactured in an ALD Vacuum Technologies furnace using the Bridgman method. Pulling out rates typical for CMSX-4 nickel superalloys were used. It has been found that in the case of monocrystalline bars the structural perfection determined based on X-ray topograms does not depend on the distance from the selector. Instead, for blades the structural perfection significantly decreases with increasing distance from the selector.

A study of the crystal orientation and structural perfection of single crystal blades obtained by Bridgeman method from CMSX‐4 nickel superalloy at various withdrawal rates between 1 and 5 mm/min was carried out using the Laue diffraction method and X‐ray diffraction topography methods as well as electron scanning microscopy. Blades consisted mainly of the regular γ' phase, with [001]γ'‐type direction close to the blade axis. The angle of deviation of the [001]γ' direction in relation to the blade axis changes between the blade locking piece and end. The dependence this angle on the distance from the locking piece has been named as the crystal orientation distribution (COD). It was found that the nature of COD changes with a change in the withdrawal rate. The change in the withdrawal rate also results in a rotation of [001]γ'‐type direction in relation to the blade axis. The best blades in terms of orientation and structural perfection were obtained for the withdrawal rate of 3 mm/min. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)