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High Temperature Oxidation Property of Ni Based Superalloy CM247LC Produced Via Selective Laser Melting Process

Lee Jung-Uk, Kim Young-Kyun, Seo Seong-Moon, Lee Kee-Ahn

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 1

107--112

EN

CM247LC alloy was manufactured by using selective laser melting (SLM) process, one of the laser powder bed fusion (L-PBF) methods. The hot isostatic pressing (HIP) process was additionally conducted on the SLM-built CM247LC to control its microstructures and defects. The high temperature oxidation property was investigated, and it was compared with conventional DS247LC sample (reference) prepared via the directional solidification process. The L-PBF HIP sample showed blocky-type MC carbides generated along the grain boundary with average size of about 200 nm. A semi-spherical primary γ' phase of size 0.4-1.0 μm was also observed inside the grains. Moreover, the DS247LC sample displayed a coarse eutectic γ' phase and many script-type MC carbides. Furthermore, cuboidal-type γ' with an average size of about 0.5 μm was detected. High-temperature oxidation tests were conducted at 1000°C and 1100°C for 24 hours. The results at 1100°C oxidation temperature showed that the measured oxidation weight gains for HIP and DS247LC were 1.96 mg/cm2 and 2.26 mg/cm2, respectively, indicating the superior high-temperature oxidation resistance of the L-PBF HIP sample. Based on the above results, a high-temperature oxidation mechanism of the CM247LC alloys manufactured by the SLM process and the directional solidification process has been proposed.

2

The Effect of Selected Process Conditions on Microstructure Evolution of the Vacuum Brazed Joints of Hastelloy X Nickel Superalloy Sheets

Krystek Kamil, Krzanowska Karolina, Wierzbińska Małgorzata, Motyka Maciej

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 4

1551--1561

EN

High temperature vacuum brazing is a well-known and commonly used method for joining of nickel based elements and subassemblies of gas turbines, both for stationary and aviation applications. Despite the fact that currently used brazing filler metals meet stringent requirements of aviation and energetic industries, a lot of effort is spent on improving operational properties of the joints through modification of chemical composition or brazing process parameters. This paper aims for both of these aspects - its purpose is evaluation of the impact of filler metal composition, brazing gap width and process conditions on the microstructure of joints between sheet metal elements made of Hastelloy X nickel superalloy. Two different Ni-based filler materials (BNi-2 and Amdry 915) were investigated, based on the results of light and scanning electron microscopy evaluations, energy dispersive X-ray spectroscopy and hardness measurements.

3

Homogeneous Dispersion of Yttrium Oxide Particles in Nickel-Based Superalloy by High Pressure Homogenizing and Ball Milling Method

Byun Jongmin, Lee Young-In, Oh Sung-Tag

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 4

1055--1058

EN

An optimum route to fabricate the Ni-based superalloy with homogeneous dispersion of Y2O3 particles is investigated. Ni-based ODS powder was prepared by high-energy ball milling of gas-atomized alloy powders and Y2O3 particles treated with a high-pressure homogenizer. Decrease in particle size and improvement of dispersion stability were observed by high-pressure homogenization of as-received Y2O3 particles, presumably by the powerful cavitation forces and by collisions of the particles. Microstructural analysis for the ball-milled powder mixtures reveal that Ni-based ODS powders prepared from high-pressure homogenization of Y2O3 particles exhibited more fine and uniform distribution of Ni and Y elements compared to the as-received powder. These results suggested that high-pressure homogenization process is useful for producing Ni-based superalloy with homogeneously dispersed oxide particles.

4

Effect of Process Control Agent on the Microstructure of Ni-Based ODS Superalloy Produced by Mechanical Alloying and Sintering

Han Ju-Yeon, Kang Hyunji, Oh Sung-Tag

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 3

949--952

EN

The effects of different types of process control agents (PCA) on the microstructure evolution of Ni-based oxide dispersion-strengthened superalloy have been investigated. Alloy synthesis was performed on elemental powders having a nominal composition of Ni-15Cr-4.5Al-4W-2.5Ti-2Mo-2Ta-0.15Zr-1.1Y2O3 in wt % using high energy ball milling for 5 h. The prepared powders are consolidated by spark plasma sintering at 1000°C. Results indicated that the powder ball-milled with ethanol as PCA showed large particle size, low carbon content and homogeneous distribution of elemental powders compared with the powder by stearic acid. The sintered alloy prepared by ethanol as PCA exhibited a homogeneous microstructure with fine precipitates at the grain boundaries. The microstructural characteristics have been discussed on the basis of function of the PCA.

5

Warstwy aluminidkowe modyfikowane Hf wytworzone na podłożu z nadstopu niklu Inconel 740H

Zagórska M., Sitek R., Kamiński J., Mizera J., Kurzydłowski K. J.

Inżynieria Materiałowa

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2015

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Vol. 36, nr 5

247--250

PL

Nadstopy niklu są powszechnie stosowanymi materiałami ze względu na swoje właściwości (m.in. żaroodporność i żarowytrzymałość). Jednak ciężkie warunki pracy elementów wykonanych z nadstopów niklu powodują zagrożenie wystąpienia m.in. korozji wysokotemperaturowej. W związku z tym jest konieczne stosowanie dodatkowej ochrony korozyjnej. W celu poprawienia właściwości nadstopów niklu wykorzystuje się ochronne warstwy powierzchniowe. Warstwy na bazie fazy międzymetalicznej NiAl charakteryzują się wysoką temperaturą topnienia, małą gęstością oraz dużą wartością modułu sprężystości. Modyfikacja warstw takimi pierwiastkami jak Hf, Zr czy Pt służy do poprawy ich adhezji oraz wytrzymałości. W artykule przedstawiono wyniki badań dotyczących warstw aluminidkowych modyfikowanych Hf wytworzonych na podłożu z nadstopu niklu Inconel 740H. Dyfuzyjne warstwy NiAl modyfikowane Hf wytworzono w wysokoaktywnym procesie CVD w temperaturze 1040°C, pod ciśnieniem 150 hPa, w obecności AlCl3 i w atmosferze wodoru jako gazu nośnego. W celu scharakteryzowania warstw wykonano badania mikrostruktury, składu chemicznego i fazowego. Wykonano także pomiary mikrotwardości od powierzchni oraz badania odporności korozyjnej. Wytworzone warstwy o grubości ok. 4 μm odznaczają się jednorodnością oraz ciągłością na całej długości próbek. Na powierzchni warstw stwierdzono występowanie trzech faz: AlNi3, Hf2Ni oraz (Al0,72Hf0,28)Ni3. Wykazano obecność wydzieleń bogatych w Hf zarówno na powierzchni, jak i w przekroju warstw. Wykazano również wpływ procesu aluminiowania na zwiększenie mikrotwardości na powierzchni (z poziomu 230 HV0,05 do około 370 HV0,05). Proces aluminiowania nieznacznie wpływa na niejednorodność elektrochemiczną stopu IN740H. Warstwy aluminiowane tworzą powłokę katodową na badanym materiale. Obecność warstw aluminiowanych zwiększa odporność korozyjną materiału w badanym roztworze korozyjnym.

EN

Ni-based superalloys are commonly used due to wide range of applications associated with their properties (such as heat and high-temperature creep resistance). However, hard working conditions of elements made of Ni-based superalloys cause a risk of high temperature corrosion occurrence. Simultaneously, it is necessary to apply additional corrosion protection. In order to improve corrosion properties of nickel based superalloys, protective coatings are used. Layers based on NiAl intermetallic phase exhibit high melting point, low density and high value of elastic modulus. Hf, Zr or Pt layers modification leads to the improvement of their adhesion and durability. This article presents characterization results of Hf-modified aluminide layer on nickel based superalloy Inconel 740H. Coatings were manufactured by CVD method at a temperature of 1040°C, at a pressure 150 hPa, in the presence of AlCl3 and in the atmosphere of hydrogen as a carrier gas. Microstructure observations, chemical and phase composition analysis were carried out in order to characterize NiAl layers. Microhardness measurements of the surface and corrosion resistance tests were also performed. Manufactured layers of thickness about 4 μm exhibit high homogeneity and continuity over entire samples. On the layers surface three phases has been identified: AlNi3, Hf2Ni and (Al0,72Hf0,28)Ni3. The presence of Hf-rich precipitates, both on the surface and in the cross-section of layers, was demonstrated. Aluminizing process effect on the increase of surface microhardness (from the 230 HV0,05 to about 370 HV0,05) was also shown. Moreover, aluminizing process slightly affects the electrochemical heterogenity of IN740H alloy. Hf-modified NiAl layers form compact cathode coating on the substrate, simultaneously increasing corrosion resistance of IN 740H alloy in applied corrosion solution.

6

The application of grain size evaluation method on non-planar surfaces in the studies of aircraft engine turbine blades

Roskosz S.

Inżynieria Materiałowa

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2010

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Vol. 31, nr 3

691-694

EN

Within the quality assurance system for products cast using the lost wax method, the grain size on the surface of that products is subject to evaluation. This paper discusses a new method to evaluate the grain size with reference to primary grain on the surface of the airfoil of aircraft engine turbine blades. The grain size evaluation was carried out on the basis of measurements taken on plane projections with the use of a stereoscopic microscope and image analysis method. The aim of the investigation was to determine the possibility of taking quantitative measurements of the structure on a non-planar surface of the airfoil of blades characterized by a variable curvature, based on measurements on a perpendicular projection of this surface.

PL

W systemie zapewnienia jakości wyrobów odlewanych precyzyjnie metodą traconego wosku ocenia się wielkość ziarna na powierzchni tych wyrobów. W artykule opisano zastosowanie nowej metody oceny wielkości ziarna do oceny ziaren pierwotnych na powierzchni pióra łopatek turbin silników lotniczych. Ocenę wielkości ziarna wykonano na podstawie pomiarów wykonywanych na płaskich projekcjach z zastosowaniem mikroskopu stereoskopowego i metod analizy obrazu. Celem badań było określenie możliwości wykonania ilościowych pomiarów struktury na niepłaskiej powierzchni pióra łopatek, charakteryzujących się zmienną krzywizną, na podstawie pomiarów na prostopadłej projekcji tej powierzchni.

7

Struktura litých lopatek ze superslitin na bázi niklu

Podrábský T.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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1999

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z. 59

83-86