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1

Anisotropic Interfacial Adhesion between Fluoropolymers and RDX Single Crystal Faces

Liu Jiahui, Zhou Xiaoqing, Qian Wen, Gong Feiyan, Yang Zhijian, Li Hongzheng, Nie Fude

Central European Journal of Energetic Materials

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2022

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Vol. 19, no. 4

409--423

EN

Interfacial interactions have an important influence on the properties of energetic materials. The anisotropy of interfacial adhesive strength between various 1,3,5-trinitro-1,3,5-triazinane (RDX) single crystal faces and a typical binder was studied in this work by experimental and theoretical investigations. An RDX single crystal was prepared and processed into three kinds of orientated crystal faces, including (002), (020) and (210). These crystal slices were used as substrates, and fluorinated polymer F2314 was used as a binder. The surfaces of the RDX slices were analyzed by X-ray photoelectron spectroscopy (XPS) and an atomic force microscope (AFM). The work of adhesion was obtained from direct tensile tests, using designed samples of the sandwich structure of RDX-F2314-RDX, with various RDX single crystal surfaces. The polarity component of the surface energy and the work of adhesion was obtained by Young’s equation and the Fowkes theory, based on surface contact angle tests. The results in this work indicated the anisotropy of the interfacial adhesion of F2314 on various RDX crystal faces.

2

Growth and study of 4-sulfobenzenaminium potassium dihydrogenphosphate for mechanical, dielectric and photonics applications

Vinoth E., Vetrivel S., Gopinath S., Mullai R. U., Aruljothi R., Suresh T.

Materials Science Poland

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2020

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Vol. 38, No. 4

619--628

EN

This article describes the growth and characterization of 4-sulfobenzenaminium potassium hydrogen phosphate (SPH) sulphanilic acid with potassium dihydrogen phosphate (KDP) doped semi-organic single crystals. The crystal was grown by the slow evaporation method. Examination of the crystalline nature of the sample was carried out by single crystal X-ray diffraction and it confirmed that the sample crystallizes in orthorhombic structure in the centrosymmetric space group P212121. The optical transmittance behavior was tested by UV-Vis spectral analysis. FT-IR spectral investigations have been carried out to indicate the presence of functional groups. The chemical structure of the compound was established by 1H and 13C NMR spectra. The SHG efficiency of the powdered SPH crystal is around 1.7 times that of pure KDP. The grown crystal was stable up to 270 °C as observed from TGA and DTA curves. The microhardness test was carried out to study the load dependency of hardness. The result of this study indicates that SPH crystal is a malleable material. From the hardness values, the stiffness constant and yield strength were calculated. The dielectric response of the novel crystal was studied in the frequency range of 50 Hz to 5 MHz at various temperatures. By employing FE-SEM, the surface morphology and the particle size of the crystal were assessed.

3

Synthesis, Characterization and Thermal Decomposition of a New Energetic Salt of 1H,1′H-5,5′-Bistetrazole-1,1′-diol

Xiao L., Jin B., Shang Y., Liu Q., Guo Z., Peng R.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 3

405--419

EN

1,1-Dimethylbiguanidium 1H,1′H-5,5′-bistetrazole-1,1′-diolate (MGBTO), a novel nitrogen-rich energetic salt, was synthesized by cation exchange. Its structure was characterized by elemental analysis, FTIR, NMR, DTA and TG-DTG. Single crystal X-ray diffraction analysis revealed that MGBTO was crystallized in the monoclinic space group C2/c. Thermal analysis demonstrated that its thermal stability extended up to 531.1 K. The nonisothermal kinetic and apparent thermodynamic parameters of the exothermic decomposition of MGBTO were determined by the Kissinger and Ozawa methods. Its detonation velocity and detonation pressure were calculated on the basis of the Kamlet-Jacobs equation and were 6342 m·s–1 and 15.78 GPa, respectively. The impact and friction sensitivities of MGBTO were quantified using standard BAM (10 kg drop hammer) procedures. The results revealed that the salt has good mechanical sensitivity (FS > 120 N, IS > 40 J), thus indicating its potential applications as an energetic material.

4

Synthesis and characterization of γ-glycine – a nonlinear optical single crystal for optoelectronic and photonic applications

Latha A. A., Anbuchezhiyan M., Kanakam C. C., Selvarani K.

Materials Science Poland

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2017

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Vol. 35, No. 1

140--150

EN

A single crystal of gamma-glycine (GG), a polymorph of glycine, was synthesized by crystallization. The single crystal of GG was grown from an aqueous solution. The morphology of GG was studied in order to assess its growth facets. The good quality single crystals were subjected to X-ray diffraction studies to reveal their structure. The FT-IR spectral analysis was carried out to confirm the presence of expected functional groups. The UV-Vis analysis was done for GG single crystals to determine the optical transparency and band gap. Simultaneous TG-DTA analysis was employed to understand the thermal and physicochemical stability of the title compound. The mechanical stability and laser stability of GG single crystal were studied using Vickers microhardness test and laser induced damage threshold on different planes of the crystal to reveal its anisotropic nature. The dielectric measurement was carried out as a function of frequency and the results were discussed. The existence of second harmonic generation (SHG) of the title compound was confirmed by Kurtz-Perry powder technique. The SHG effective nonlinearity and particle size dependence of GG powder sample were compared with a standard reference material: potassium dihydrogen phosphate (KDP).

5

Microstructural characterization of creep in the single crystal superalloy CMSX–4

Albrecht R., Bogdanowicz W., Gancarczyk K., Rak J., Sieniawski J., Kubiak K., Lelątko J.

Inżynieria Materiałowa

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2017

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Vol. 38, nr 1

15--19

EN

Blades and vanes structural components of turbine engines are processed to withstand high temperature during loading conditions of service, fulfilling high standards of quality control and safety for effective use. Therefore, characterization of mechanical properties, such as creep behaviour, are necessary for appropriate control procedures on prediction of exploitation lifetime. The materials mostly used in manufacturing of these components are single crystal nickel-base superalloys. Creep behaviour characterization, composed of creep-rupture tests, were performed on a single crystal rods made of CMSX–4 superalloy obtained at a withdrawal rate of 3 and 5 mm/min. Cylindrical rods were directly solidified in the [001] direction in an ALD Vacuum Technologies investment casting furnace (VIM-IC 2). Then, prepared specimens were tested in tensile creep under constant stress of 248 MPa at a temperature of 982°C. The longitudinal and cross sections from tested samples, were characterized by TEM and X-ray diffraction methods. It was found that all samples showed a similar rupture mechanism. The electron backscatter diffraction (EBSD) measurements showed that octahedral and cubic slip systems were present however, the critical stress was present on {111} planes. It was observed that the cubic slip has the highest calculated Schmid factor along the dendrite cores while the octahedral slip occurs through entire sample volume. Samples obtained at 5 mm/min possess a visible widening of coherent scattering regions as shown in inverse pole figures. The reason of these changes is the fact that higher rate has the greatest probability of creating small angle boundaries, often occurring in the interdendritic channels.

PL

Monokrystaliczne odlewy nadstopu niklu CMSX–4 stosuje się na najbardziej wytężone elementy silnika odrzutowego, takie jak łopatki turbiny wysokiego ciśnienia. Musza one charakteryzować się dużą żarowytrzymałością oraz żaroodpornością. Dlatego jest ważne precyzyjne określenie wpływu zjawiska pełzania na strukturę tego materiału w zależności od warunków jego wytwarzania. Celem pracy było scharakteryzowanie zmian strukturalnych oraz określenie wytrzymałości na pełzanie monokrystalicznych odlewów otrzymanych z prędkościami wyciągania formy wynoszącymi 3 oraz 5 mm/min.

6

Numerical Simulation of Directional Solidification Process of Single Crystal Ni- Based Superalloy Casting

Szeliga D., Kubiak K., Sieniawski J.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

111--118

EN

The analysis of influence of mould withdrawal rate on the solidification process of CMSX-4 single crystal castings produced by Bridgman method was presented in this paper. The predicted values of temperature gradient, solidification and cooling rate, were determined at the longitudinal section of casting blade withdrawn at rate from 1 to 6mm/min using ProCAST software. It was found that the increase of withdrawal rate of ceramic mould results in the decrease of temperature gradient and the growth of cooling rate, along blade height. Based on results of solidification parameter G/R (temperature gradient/solidification rate), maximum withdrawal rate of ceramic mould (3.5 mm/min), which ensures lower susceptibility to formation process of new grain defects in single crystal, was established. It was proved that these defects can be formed in the bottom part of casting at withdrawal rate of 4 mm/min. The increase of withdrawal rate to 5 and 6 mm/min results in additional growth of susceptibility of defects formation along the whole height of airfoil.

7

Wpływ doskonałości struktury monokryształów nadstopu niklu na ich wytrzymałość na pełzanie

Gancarczyk K., Gradzik A., Sieniawski J.

Hutnik, Wiadomości Hutnicze

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2016

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Vol. 83, nr 10

449--451

PL

W artykule przedstawiono ocenę doskonałości struktury krystalicznej monokrystalicznego odlewu z nadstopu niklu CMSX-4 o strukturze mozaikowej. Do oceny doskonałości struktury przyjęto wartości kąta odchylenia αz – pomiędzy kierunkiem wyciągania odlewu i kierunkiem [001] oraz kąt dezorientacji αb – pomiędzy blokami mozaiki. Stwierdzono, że kąt odchylenia na powierzchni podłużnej odlewu, jak i na jego przekroju poprzecznym, przyjmuje wartości w zakresie 15,6–17,8° oraz 13,8–16,0° i 16,0–17,0°, natomiast kąt dezorientacji bloków mozaiki przyjmuje wartości w zakresie 1,08 – 1,35°. Próba pełzania wykonana dla fragmentów odlewu o różnych wartościach kątów αz i αb wykazała wpływ wartości kąta odchylenia kierunku [001] od kierunku wyciągania na odporność na pełzanie.

EN

The paper presents an analysis of crystal structure perfection of single crystal nickel-based superalloy CMSX-4 with blocky structure. Evaluation of crystalline structure was based on measurements of the value of αz angle - between the direction of crystallization and the direction [001] and αb angle – misorientation of the structure blocks. The measured values of αz on the cast surface was from 15.6 to 17.8° and from 13.8 to 16.0° and on the crosssection of cast in the range of 16.0–17.0°. The misorientation angle of blocky structure αb has a value from 1.08 to 1.35°. Creep resistance of single crystal was evaluated on specimens with various values of αz and αb. The influence of the value of angle αz and αb on the creep resistance of the single crystal was determined.

8

Microstructure Evolution and Texture Development in a Cu-8.5%AT. AL Material Subjected to Hydrostatic Extrusion

Jakubowska D., Zdunek J., Kulczyk M., Mizera J., Kurzydłowski K. J.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2B

933--936

EN

The aim of the present paper was to investigate microstructure and texture evolution of two single crystals and polycrystal of Cu-8.5%at.Al material. All of mentioned samples were deformed by HE to achieve true strain ε = 1.17. For microstructure analyzes observations by transmission electron microscope (STEM) were done. Crystalline size for samples after SPD were determine using XRD method. The global texture measurements were done using Bruker D8 Discover diffractometer equipped in Cr radiation. Microstructure investigations revealed nanocrystalline structure in single crystals with initial orientations <110> and <100> and polycrystalline Cu-8.5%at.Al material after SPD. The global texture measurements have shown the stability of initial orientation of <100> Cu-8.5%at.Al single crystal after HE, whereas the same SPD process strongly brakes up the orientation <110> Cu-8.5%at. Al single crystal.

9

A minimal gradient-enhancement of the classical continuum theory of crystal plasticity. Part I: The hardening law

Petryk H., Stupkiewicz S.

Archives of Mechanics

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2016

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Vol. 68, nr 6

459--485

EN

A simple gradient-enhancement of the classical continuum theory of plasticity of single crystals deformed by multislip is proposed for incorporating size effects in a manner consistent with phenomenological laws established in materials science. Despite considerable efforts in developing gradient theories, there is no consensus regarding the minimal set of physically based assumptions needed to capture the slip-gradient effects in metal single crystals and to provide a benchmark for more refined approaches. In order to make a step towards such a reference model, the concept of the tensorial density of geometrically necessary dislocations generated by slip-rate gradients is combined with a generalized form of the classical Taylor formula for the flow stress. In the governing equations in the rate form, the derived internal length scale is expressed through the current flow stress and standard parameters so that no further assumption is needed to define a characteristic length. It is shown that this internal length scale is directly related to the mean free path of dislocations and possesses physical interpretation which is frequently missing in other gradient-plasticity models.

10

Sposób oceny doskonałości struktury krystalicznej monokrystalicznych odlewów łopatek z nadstopu niklu CMSX-4

Gancarczyk K., Albrecht R., Olesch Ch., Kubiak K., Sieniawski J.

Inżynieria Materiałowa

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2015

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Vol. 36, nr 6

356--362

PL

W pracy przedstawiono ocenę doskonałości struktury krystalicznej monokrystalicznych odlewów łopatek turbiny wysokiego ciśnienia silnika lotniczego w stanie lanym oraz po obróbce cieplnej. Odlewy wytworzono z nadstopu niklu CMSX-4 metodą Bridgmana z prędkością wyciągania formy 3 i 5 mm/min. Podstawą oceny doskonałości struktury krystalicznej odlewów była analiza wyników pomiarów kąta odchylenia α pomiędzy kierunkiem wyciągania i kierunkiem krystalograficznym [001] w danej objętości odlewu łopatki. Stosowano zmodyfikowaną metodę dyfrakcji rentgenowskiej Ω-scan do wyznaczania orientacji krystalicznej monokryształów za pomocą zaprojektowanego i wykonanego dyfraktometru firmy EFG. Metoda ta umożliwia wyznaczanie orientacji krystalicznej poszczególnych obszarów powierzchni pióra i zamka odlewu monokrystalicznego łopatki z dokładnością ±0,01°. Analiza uzyskanych wyników badań wskazuje, że zwiększenie prędkości wyciągania z 3 do 5 mm/min prowadzi do zmniejszenia średniej wartości kąta odchylenia α od około 6,5 do 4°. Stwierdzono jednocześnie, że różnica wartości kąta α dla prędkości wyciągania 3 i 5 mm/min jest zbliżona. Jednocześnie wykazano, że obróbka cieplna odlewów (przesycanie i starzenie) prowadzi do zwiększenia średniej wartości kąta odchylenia α dla prędkości 3 i 5 mm/min odpowiednio do około 8,5 i 6,5°. Stwierdzono także, że rozkład wartości kąta α będący miarą niejednorodności orientacji zmniejsza się dla prędkości wyciągania 3 i 5 mm/min odpowiednio do 1,8 i 1,6°.

EN

The paper presents novel method for crystal perfection investigation in single crystal turbine blades both as-cast and after heat treatment. The castings were made of CMSX-4 superalloy and cast by the Bridgman method at the withdrawal rate of 3 and 5 mm/min. Evaluation of crystal perfection was based on measurements of α angle — the angle between crystallographic growth direction [001] and the main axis of the blade z. The investigation was conducted with the use of X-ray diffraction method called Ω-scan, utilizing prototype OD-EFG diffractometer invented by EFG company (Berlin). The apparatus enables determination of the crystal orientation in the root and airfoil of turbine blade made of nickel based superalloys. The size of the measuring spot was about approx. 2 mm2 and by this size, the orientation of whole surface of turbine blade can be mapped with an accuracy of ±0.01°. It was found that increase of withdrawal rate from 3 to 5 mm/min caused a reduction in the average value of α angle from 6.5 to 4°. The scatter of α angle for both withdrawal rates is similar. Heat treatment of casting resulted in an increase of α angle to 8.5° for withdrawal rate 3 mm/min and 6.5° for 5 mm/min. The scatter of orientation decreased to 1.8 and 1.6° respectively.

11

The Internal Friction of Single Crystals, Bicrystals and Polycrystals of Pure Magnesium

Jiang W. B., Kong Q. P., Magalas L. B., Fang Q. F.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 1

371--375

EN

The internal friction of magnesium single crystals, bicrystals and polycrystals has been studied between room temperature and 450°C. There is no internal friction peak in the single crystals, but a prominent relaxation peak appears at around 160°C in polycrystals. The activation energy of the peak is 1.0 eV, which is consistent with the grain boundary self-diffusion energy of Mg. Therefore, the peak in polycrystals can be attributed to grain boundary relaxation. For the three studied bicrystals, the grain boundary peak temperatures and activation energies are higher than that of polycrystals, while the peak heights are much lower. The difference between the internal friction peaks in bicrystals and polycrystals is possibly caused by the difference in the concentrations of segregated impurities in grain boundaries.

PL

Badania tarcia wewnętrznego w monokryształach, bikryształach i polikryształach magnezu przeprowadzono w zakresie temperatur między temperaturą pokojową a 450°C. W monokryształach magnezu nie występuje pik tarcia wewnętrznego, ale wyraźny pik relaksacyjny pojawia się przy około 160°C w polikryształach. Energia aktywacji piku wynosi 1,0 eV, co jest zgodne z energią autodyfuzji Mg przez granice ziaren. Z tego względu pik tarcia wewnętrznego występujący w polikryształach można przypisać relaksacji granic ziaren. W przypadku trzech badanych bikryształów temperatury pików pochodzących od granic ziaren i ich energie aktywacji są wyższe niż w przypadku polikryształów, ale wysokości tych pików są znacznie niższe. Różnica między pikami tarcia wewnętrznego w bikryształach i polikryształach jest prawdopodobnie spowodowana przez różnicę stężeń zanieczyszczeń segregujących na granicach ziaren.

12

Czochralski-Based Growth and Characteristics of Selected Novel Single Crystals for Optical Applications

Shimamura K., Víllora E. G.

Zeszyty Historyczne Politechniki Warszawskiej

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2014

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z. 16

113--121

EN

In the Year of Professor Jan Czochralski, we with pleasure review the representative recent works of our group, Optical Single Crystals Group, NIMS, Japan. Our group has been working on the development of novel single crystals for optical applications based on the Czochralski technique. Here, 4 kinds of topics are reviewed. 1st one is ferroelectric fluoride BaMgF4 single crystals for UV nonlinear optical applications including quasi-phase matching device fabrications. 2nd one is transparent conductive β-Ga2O3 single crystals as semiconductor, which has large band-gap, 4.8 eV, for LED applications. 3rd one is F-doped core-free Y3Al5O12 single crystals as a potential new lens material for UV/VUV wavelength region. Last one is superior magneto-optical {Tb3}[Sc2-xLux](Al3)O12 single crystals for near infrared to visible region, and CeF3/PrF3 single crystals for UV region.

13

Czochralski growth of SrLaAlO4 and SrLaGaO 4 single crystals and its implications for the crystal morphology

Pajaczkowska A., Gloubokov A., Klos A., Woensdregt C. F.

Zeszyty Historyczne Politechniki Warszawskiej

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2014

|

z. 16

85--89

EN

Single crystals of SrLaAlO4 (SLA) and SrLaGaO4 (SLG) have been grown from nonstoichiometric melts by the Czochralski method making use of different seed orientations, [100] (SLA, SLG), [110] (SLA) and [001] (SLG). The anisotropic properties of the crystal structure are reflected in the growth morphology of the crystals. In the case of (SLA) {101} facets appear at the crystal/melt interface and in that of [100] SLG {101} and {103} facets occur, while for [001] SLG {001} and {103} facets are present. SLA crystals are very similar to the theoretical growth forms computed according to the Hartman-Perdok theory for models with an effective charge on oxygen, qO −2|e|. However the habit of SLG crystals corresponds better to the theoretical growth forms based on an effective charge qO = −1.5|e| due to the presence of oxygen vacancies.

14

Badanie struktury elektronowej i własności magnetycznych monokryształów związków międzymetalicznych R-T (R - pierwiastek ziem rzadkich, T - metal przejściowy 3d, 4d, 5d)

Talik E.

Zeszyty Historyczne Politechniki Warszawskiej

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2014

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z. 16

7--22

15

Temperature dependence of Bi4Ge3O12 photoluminescence spectra

Kaczmarek S. M., Tsuboi T., Nakai Y, Berkowski M., Huang W., Kowalski Z.

Materials Science Poland

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2014

|

Vol. 32, No. 1

7--11

EN

Bi4Ge3O12 single crystals were obtained using Czochralski growth method. Photoluminescence spectra were analyzed versus temperature from 12 to 295 K. Besides the previously observed emission bands at 610 and 820 nm, the new emission band at 475 nm was found by a careful temperature dependence measurement in the present study. The influence of basic and defect structure on the shape and position of the spectra versus temperature was discussed.

16

Electron spin resonance of FeVO4

Bojanowski B, Kaczmarek S. M.

Materials Science Poland

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2014

|

Vol. 32, No. 2

188--192

EN

We report on electron spin resonance (ESR) investigations of a FeVO4 single crystal. Temperature and angular dependences of ESR resonance positions were measured and calculated in temperature range of 35 – 100 K. The spectra show rich angular dependences of the linewidth, the shape and the resonance field. They consist of a single broad line with asymmetric distortion. Due to the low symmetry of the crystal lattice this distortion can be explained by taking into account the influence of non diagonal dynamic susceptibility.

17

Eutectic Structures Competition in the Stripes Strengthening the (Zn) – Single Crystal

Wołczyński W., Kjelstrup S., Bedeaux D., Szajnar J., Billia B.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 4

95--102

EN

Some eutectic stripes have been generated in a hexagonal (Zn) - single crystal. The stripes are situated periodically with the constant inter stripes spacing. The eutectic structure in the stripes consists of strengthening inter-metallic compound, Zn16Ti, and (Zn) – solid solution. The rod-like irregular eutectic structure (with branches) appears at low growth rates. The regular lamellar eutectic structure is observed at middle growth rates. The regular rod-like eutectic structure exists exclusively in the stripes at some elevated growth rates. A new thermodynamic criterion is recommended. It suggests that this eutectic regular structure is the winner in a morphological competition for which the minimum entropy production is lower. A competition between the regular rod-like and the regular lamellar eutectic growth is described by means of the proposed criterion. The formation of branches within irregular eutectic structure is referred to the state of marginal stability. A continuous transitions from the marginal stability to the stationary state are confirmed by the continuous transformations of the irregular eutectic structure into the regular one.

18

Relacje dezorientacji w początkowych stadiach rekrystalizacji metali o sieci RSC o średniej i małej energii błędu ułożenia

Miszczyk M., Paul H., Driver J.H., Maurice C.

Rudy i Metale Nieżelazne

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2013

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R. 58, nr 11

748--754

PL

Mechanizm stanowi ciągle silnie nierozpoznane zagadnienie. Jednym z kluczowych zagadnień związanych z opisem mechanizmów zarządzających procesem przemiany tekstury podczas wyżarzania jest identyfikacja typu granicy poprzez migrujący front rekrystalizacji. Celem niniejszej pracy było określenie dominujących relacji orientacji, pomiędzy stanem odkształconym a nowo powstałymi ziarnami we wczesnych stadiach rekrystalizacji w metalach o sieci regularnie ściennie centrowanej, o średniej i małej energii błędu ułożenia. Analizę prowadzono na monokryształach o orientacjach stabilnych w płaskim stanie odkształcenia, tj. „Goss”{110}<001> oraz „brass”{110}<112>. Monokrystaliczne próbki z Ni, Cu, Cu-2%Al odkształcono w próbie nieswobodnego ściskania do ok. 40 %. Następnie odkształcony materiał został poddany wyżarzaniu celem analizy preferencji w występowaniu relacji orientacji poprzez front rekrystalizacji. Analizę przeprowadzono z wykorzystaniem wysokorozdzielczej skaningowej mikroskopii elektronowej i techniki dyfrakcji elektronów wstecznie rozproszonych (SEM-FEG/EBSD). Przeprowadzona analiza preferencji w rozkładzie osi i kąta dezorientacji poprzez front rekrystalizacji pokazuje, że relacje dezorientacji zbliżone do 40°<111> są realizowane jedynie sporadycznie. Wykazano, że dominują rolę odgrywają dezorientacje określone kątami z zakresów 25-35° i 45-55° oraz obrotem dookoła osi <122>, <012>, <112> zgrupowanych zazwyczaj w pobliżu normalnych do wszystkich czterech płaszczyzn {111}.

EN

The objective of this paper is to identify the predominant crystallographic relations between deformed state and recrystallized grains during the early stages of recrystallization of fcc metals with medium and low stacking fault energy. The experimental investigations, based on high resolution SEM/EBSD measurements, have focused on the transformations which occur in plane strain compressed single crystals with stable orientations. After annealing the disorientation across the recrystallization front defines the final rotation by angles in the ranges of 25-35° and 45-55° around axes mostly grouped near the <122>, <012>, <112> and <111> directions located around the normals of all four {111} slip planes.

19

Structure of single-crystalline turbine blades grown from CMSX-4 superalloy

Lelątko J., Bogdanowicz W., Dercz G., Albrecht R., Rak J., Sieniawski J., Stróż D.

Inżynieria Materiałowa

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2013

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Vol. 34, nr 4

317--319

EN

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 fumace by the Bridgman technique. Crystallization process was carried out with withdraw rates of 1 mm/min, 3 mm/min and 5 mm/min. High withdraw rate of crystallization can lead to formation many different type of defects such as freckles or high and low angle boundaries, presence of other phases which may be inﬂuenced by subsequent thennal treatment. The dendrite microstructure based on the y/y' phases and they defects was characterized using X-ray topography, Laue diffraction, optical microscopy and scanning electron microscopy. The phase and microstructure were analyzed using X-ray diffraction and transmission electron microscopy. It was found that crystal orientation, lattice parameter of y' phase, concentration of defects and the quantity of y + y' eutectic structure are correlated with withdraw rate of single crystal of the superalloy. The defect concentration increase in some areas which was the result of deviation of primary dendrite arm from crystallization direction. Increase of the crystallization rate from 3 to 5 mm/min results in increase of the direction deviation of the blade axis from <001> direction from 7 to 18 angular degrees. Also, the change of the phase composition was observed. Apart from y and y' the Ni6AlTa phase was identiﬁed. The quantity of this phase increases with increasing withdraw rates of blades. The changes in defect structure, deviation direction and phase composition with the withdraw rates of single-crystal CMSX-4 will inﬂuence the turbine blades quality.

PL

Monokrystaliczne nadstopy niklu są używane do wytwarzania wysokociśnieniowych łopatek turbin. Badane w prezentowanej pracy łopatki wytworzono metodą Bridgemana. Proces krystalizacji prowadzono przy szybkości wyciągania 1 mm/min, 3 mm/min i 5 mm/min. Szybkość krystalizacji bezpośrednio wpływa na liczbę tworzących się dyslokacji, na granice nisko- i szerokokątowe oraz obecność innych faz. Struktura dendrytyczna złożona z faz y i y' i struktura defektowa były charakteryzowane za pomocą topograﬁi rentgenowskiej, dyfrakcji Lauego, mikroskopu świetlnego oraz skaningowego mikroskopu elektronowego. Skład fazowy i mikrostrukturę nadstopu niklu badano, używając rentgenowskiej analizy fazowej i transmisyjnej mikroskopii elektronowej. Stwierdzono, że orientacja monokryształu, parametr sieci krystalicznej fazy y', koncentracja defektów i ilość eutektyki y + y' silnie zależą od szybkości wyciągania łopatek z nadstopu niklu. Koncentracja defektów, W niektórych obszarach zwiększa się jako wynik odchylenia kierunku wzrostu pierwotnych dendrytów od kierunku krystalizacji. Zwiększenie szybkości krystalizacji z 3 mm/min do 5 mm/min powoduje zwiększenie kąta odchylenia osi łopatki od kierunku krystalizacji <001> z 7 do 18 stopni kątowych. Równocześnie obserwowano zmiany składu fazowego nadstopu. Oprócz faz y i y' identyﬁkowano fazę Ni6AlTa. Ilość tej fazy zwiększa się wraz ze wzrostem szybkości wyciągania łopatek. Zmiany w strukturze defektów, wielkości kąta odchylenia kierunku krystalizacji oraz składu fazowego uwarunkowane szybkością wyciągania monokrystalicznych nadstopów CMSX-4 będą wpływać na parametry późniejszej obróbki cieplnej, a w konsekwencji na jakość wytwarzanych łopatek do turbin.

20

Rozkład wartości temperatury w monokrystalicznym odlewie z nadstopu niklu CMSX-4 wytwarzanym metodą Bridgmana

Szeliga Dariusz, Kubiak Krzysztof, Suchy Józef Szczepan, Jarczyk Georg, Sieniawski Jan

Inżynieria Materiałowa

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2013

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Vol. 34, nr 1

7--12

PL

W pracy przedstawiono analizę wyników pomiarów i symulacji numerycznej rozkładu wartości temperatury W monokiystalicznym odlewie pręta z nadstopu niklu CMSX-4 wytwarzanego metodą Bridgmana. Opracowano model geometryczny zestawu modelowego i przestrzennego otoczenia formy ceramicznej oraz przyjęto warunki brzegowe. Ustalono wpływ kształtu modelu geometrycznego i zadanych warunków brzegowych na wyniki symulacji numerycznej procesu krystalizacji monokrystalicznego odlewu w danych warunkach technologicznych. Wykonano symulację numeryczną procesu krystalizacji kierunkowej oraz ustalono rozkład wartości temperatury w odlewie, formie ceramicznej, płycie izolacji cieplnej oraz przegrodzie cieplnej z zastosowaniem programu ProCAST. Określono wpływ wartości współczynników: wymiany ciepła na styku dwóch materiałów, emisyjności formy ceramicznej, a także właściwości cieplnych i fizycznych stopu CMSX-4 na rozkład wartości temperatury w odlewie. Przeprowadzono weryfikację doświadczalną przyjętych warunków brzegowych i wartości współczynników cieplnych i fizycznych materiałów odlewu i formy ceramicznej. Stwierdzono, że największy wpływ na prognozowany rozkład wartości temperatury w odlewie mają wartości współczynnika wymiany ciepła na styku powierzchni odlewu i formy ceramicznej oraz współczynniki cieplne i fizyczne materiału odlewu i formy.

EN

The authors conducted analysis of the measurement results and performed a numerical simulation of the temperature distribution in a single crystal cast rod made of the CMSX-4 nickel superalloy, which was manufactured by the Bridgman method. The geometric model of the model set and of the ceramic shell mold surrounding it were developed (Fig. 3) and the boundary conditions were selected (Fig. 4+6) (Tab. 1, 2). The infiuence of the shape of the geometric model and the boundary conditions on the numerical simulation results of the solidification process of a single crystal cast under given technological conditions was determined. The numerical simulation of the directional solidification process was performed and the temperature distribution in the cast, the ceramic shell mold, the thermal insulating plate and the thermal baffie was determined using the ProCAST program (Fig. 11). The infiuence of the emissivity coefficient of the ceramic shell mold, the heat transfer coefficient on the contact surface of the two materials as well as the infiuence of the thermal and physical properties of the CMSX-4 superalloy on the temperature distribution in the cast were determined (Fig. 7+10). The authors conducted experimental verification of the selected boundary conditions as well as the thermal and physical coefficients values for the cast material and the material of the ceramic shell mold. It has been proved that the value of the heat transfer coefficient on the contact surface of the cast and the ceramic shell mold as well as the thermal and physical coefficients values have the greatest infiuence on the temperature distribution in the cast.