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1

Effect of ball milling on hexagonal boron nitride (hBN) and development of Al-hBN nanocomposites by powder metallurgy route

Ghosh Arka, Shukla Uddeshya, Sahoo Nityananda, Ganguly Sourav, Shrivastava Pankaj, Kumar Lailesh, Alam Syed Nasimul

Materials Science Poland

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2023

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Vol. 41, No. 1

68--93

EN

This study reports on the exfoliation of bulk hexagonal boron nitride (hBN) by high-energy ball milling and the development of Al-hBN (alumninum-hexagonal boron nitride) nanocomposites by the powder metallurgy (PM) route via the incorporation of the exfoliated hBN in the Al matrix as a nanoreinforcement. The effect of ball milling on the morphology, crystallite size, lattice strain, and thermal stability of hBN powder have also been reported in this paper. Commercially available bulk hBN was ball milled for up to 30 hours in a high-energy planetary ball mill in order to exfoliate the hBN. Although no new phases were formed during milling, which was confirmed by the XRD (x-ray powder diffraction) spectra, ball milling resulted in the attachment of functional groups like hydroxyl (OH) and amino (NH2) groups on the surface of the hBN, which was confirmed by FTIR (Fourier Transform Infrared Spectroscopy) analysis. HRTEM (high resolution transmission electron microscopy) analysis confirmed the synthesis of hBN having few atomic layers of hBN stacked together after 20 hours of milling. After 20 hours of milling, the hBN particle size was reduced from ~1 μm to ~400 nm, while the crystallite size of the 20-hourmilled hBN powder was found to be ~18 nm. Milling resulted in a flake-like structure in the hBN. Although milling involved both exfoliation as well as reagglomeration of the hBN particles, a significant decrease in the diameter of the hBN particles and their thickness was observed after a long period of milling. The average thickness of the 20-hour-milled hBN flakes was found to be ~32.61 nm. HRTEM analysis showed that the hexagonal structure of the milled hBN powder was maintained. Al-based nanocomposites reinforced with 1%, 2%, 3%, and 5% by weight hBN were fabricated by PM route. The Al-hBN powder mixtures were cold-compacted and sintered at 550◦C for 2 hours in argon (Ar) atmosphere. The maximum relative density of ~94.11% was observed in the case of Al-3 wt.% hBN nanocomposite. Al-3 wt.% hBN nanocomposite also showed a significant improvement in hardness and wear resistance compared to the pure Al sample that was developed in a similar fashion. The maximum compressive strength of ~999 MPa was observed in the case of Al-3 wt.% hBN nanocomposite and was approximately twice that of the pure Al sample developed in a similar fashion.

2

Effect of graphite nanoplatelets on spark plasma sintered and conventionally sintered aluminum-based nanocomposites developed by powder metallurgy

Shrivastava Pankaj, Alam Syed Nasimul, Maity Taraknath, Biswas Krishanu

Materials Science Poland

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2021

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Vol. 39, No. 3

346--370

EN

In this work, aluminum (Al)-based nanocomposites reinforced with graphite nanoplatelets (GnPs) have been fabricated by conventional sintering as well as spark plasma sintering (SPS) techniques, and their microstructure and mechanical properties have been studied. The powder metallurgy (PM) route has been adopted to fabricate the various Al–GnP nanocomposites. Characterization of the powder mixtures and the nanocomposites has been carried out through different characterization techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. Compressive strength, Young's modulus, density, and Vickers microhardness of the various nanocomposites have also been determined. The HRTEM results show the formation of nonstoichiometric Al4C3 nanoparticles – during both conventional sintering and SPS – at the interface of the Al grains and GnP, which worsen the mechanical properties of the nanocomposites. SPSed nanocomposites show superior mechanical properties due to higher densification, finer grain size, and homogeneous nanofiller dispersion in the Al matrix, compared to the conventionally sintered Al–GnP nanocomposites.

3

Synthesis and optical properties of CdSe/CdS core/shell nanocrystals

Gadalla A., Abd El-Sadek M. S., Hamood R.

Materials Science Poland

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2019

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Vol. 37, No. 2

149--157

EN

This paper attempts to describe an effective method for producing a composite of quantum dots consisting of CdSe (core) with CdS (shell). This nanoparticles composite was synthesized from modified organometallic precursors. The sizes of the nanoparticles were estimated from X-ray diffraction data using Debye-Scherer formula and compared with high resolution electron microscopy (HRTEM) and optical spectra. The shape of CdSe/CdS NPs is nearly spherical and revels that the CdS shell with the thickness ~0.6 nm almost fully covers the CdSe core (higher contrast). Using UV-Vis spectroscopy, a systematic red shift in the absorption and emission spectra was observed after the deposition of CdS which confirms the shell growth over the CdSe core. In the CdSe/CdS core/shell structure, the holes are confined to the core, while the electrons are delocalized as a result of similar electron affinities of the core and the shell. The increased time of synthesis resulted in shell thickness increase. The observed properties of prepared CdSe/CdS QDs demonstrate the capability of the nanocomposite for using in the optoelectronics and photonics devices.

4

Nanostruktury tlenku miedzi w zastosowaniach fototermicznych

Stępińska Izabela, Czerwosz Elżbieta

Elektronika : konstrukcje, technologie, zastosowania

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2019

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Vol. 60, nr 12

45--49

PL

W pracy przedstawiono wyniki badań strukturalnych wykonanych za pomocą skaningowej i transmisyjnej mikroskopii elektronowej, dyfrakcji rentgenowskiej oraz spektroskopii w podczerwieni tlenku miedzi w postaci nanodrutów otrzymanych w procesie termicznego utleniania. Ponadto przeprowadzono eksperymenty oddziaływania promieniowania elektromagnetycznego z nanodrutami CuO.

EN

In this work the results of structural studies, performed by scanning electron microscopy and transmission electron microscopy, X-ray diffraction and infrared spectroscopy of copper oxide in nanorods form obtained in thermal oxidation, were presented. Moreover, interaction between CuO nanorods and electromagnetic radiation was investigated.

5

Optimisation of Mechanical Properties of 18%Ni350 Grade Maraging Steel Using Novel Heat Treatment

Marcisz J., Adamczyk M., Garbarz B.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 1

73--84

EN

The paper presents results of examinations of properties and microstructure of maraging steel grade MS350 (18Ni350) produced by a novel heat treatment method called „short-time ageing“. It has been found that maraging steel after application of the short-time ageing achieves unique properties, in particular good combination of strength and impact toughness. After short-time ageing for time of heating up to 600 seconds at temperature of 550°C hardness in the range from 48 to 56 HRC, tensile strength ranging from 2000 to 2250 MPa, yield strength from 1930 to 2170 MPa and total elongation in the range 7-8% as well as notch impact toughness of 20 J/cm2 at temperature minus 40°C were obtained. Results of microstructure examination in transmission electron microscope (TEM) with application of high resolution technique (HRTEM) have shown presence of Ni3Mo nano-precipitates of orthorhombic crystallographic structure. Precipitates were characterized by rod-like shape and were homogenously distributed in martensitic matrix of steel with high density of dislocations. The average size of cross-section of precipitates was ca. 4 nm while length reached several dozen of nm.

6

Structure and properties of diamond-like carbon films deposited by pacyd technique on light alloys

Tański T., Labisz K., Krupiński M., Lukaszowicz K., Krzemiński Ł.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 3

1321--1330

EN

The investigations presented in this paper describe surface treatment performed on samples of heat-treated cast magnesium and aluminium alloy. The structure and chemical composition as well as the functional and mechanical properties of the obtained gradient/monolithic films were analysed by high resolution transmission electron microscopy and scanning electron microscopy, Raman spectroscopy, die ball-on-disk tribotester and scratch testing. Moreover, investigation of the electrochemical corrosion behaviour of the samples was carried out by means of potentiodynamic polarisation curves in 1-M NaCl solution. The coatings produced by chemical vapour deposition did not reveal any delamination or defects and they adhere closely to the substrate. The coating thickness was in a range of up to 2.5 microns. Investigations using Raman spectra of the DLC films confirmed a multiphase character of the diamond-like carbon layer, revealing the sp and sp³ electron hybridisation responsible for both the hardness and the friction coefficient. The best wear resistance test results were obtained for the magnesium alloy substrate - AZ61, for which the measured value of the friction path length was equal to 630 m.

7

Nano-Scale Structure Investigation of Vapour Deposited AlCrSiN Coating Using Transmission Electron Microscope Techniques

Lukaszkowicz K., Labisz K., Basiaga M., Jonda E.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

837--842

EN

The investigations concerned the structural analysis of the AlCrSiN coating deposited by arc Physical Vapour Deposition method on the X40CrMoV5-1 hot work tool steel substrate. The deposition process was carried out on a device equipped with a technique of lateral, rotating cathodes. The nano/microstructure, phase identification and chemical state of the coating were analysed by high-resolution transmission electron microscopy. It was found that the investigated coatings have nanostructured nature consisting of fine crystallites. The fractographic tests were made using the scanning electron microscope and allow to state, that the coating was deposited uniformly and tightly adhere to the substrate material. In the work is presented the nature of a transition zone between the produced AlCrSiN coating and substrate material.

8

Characterization of Nanometric-Sized Carbides Formed During Tempering of Carbide-Steel Cermets

Matus K., Pawlyta M., Matula G., Gołombek K.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

747--752

EN

The aim of this article of this paper is to present issues related to characterization of nanometric-sized carbides, nitrides and/or carbonitrides formed during tempering of carbide-steel cermets. Closer examination of those materials is important because of hardness growth of carbide-steel cermet after tempering. The results obtained during research show that the upswing of hardness is significantly higher than for high-speed steels. Another interesting fact is the displacement of secondary hardness effect observed for this material to a higher tempering temperature range. Determined influence of the atmosphere in the sintering process on precipitations formed during tempering of carbide-steel cermets. So far examination of carbidesteel cermet produced by powder injection moulding was carried out mainly in the scanning electron microscope. A proper description of nanosized particles is both important and difficult as achievements of nanoscience and nanotechnology confirm the significant influence of nanocrystalline particles on material properties even if its mass fraction is undetectable by standard methods. The following research studies have been carried out using transmission electron microscopy, mainly selected area electron diffraction and energy dispersive spectroscopy. The obtained results and computer simulations comparison were made.

9

A facile thermal decomposition route to synthesise CoFe2O4 nanostructures

Kalpanadevi K, Sinduja C R, Manimekalai R

Materials Science Poland

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2014

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Vol. 32, No. 1

34--38

EN

The synthesis of CoFe2O4 nanoparticles has been achieved by a simple thermal decomposition method from an inorganic precursor, cobalt ferrous cinnamate hydrazinate (CoFe2(cin)3(N2H4)3) which was obtained by a novel precipitation method from the corresponding metal salts, cinnamic acid and hydrazine hydrate. The precursor was characterized by hydrazine and metal analyses, infrared spectral analysis and thermo gravimetric analysis. Under appropriate annealing, CoFe2(cin)3(N2H4)3 yielded CoFe2O4 nanoparticles, which were characterized for their size and structure using X-Ray diffraction (XRD), high resolution transmission electron microscopic (HRTEM), selected area electron diffraction (SAED) and scanning electron microscopic (SEM) techniques.

10

Short-Time Ageing of MS350 Maraging Steel with and Without Plastic Deformation

Marcisz J., Stępień J.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 2

513--520

EN

The age hardening behaviour of MS350 maraging steel both in undeformed specimens and in specimens deformed immediately after ageing was studied. Experiments of short-time (15, 30 and 60 s) ageing at temperature up to 600°C were performed. It was found that after ageing at 480-500°C for 15-60 s without deformation the hardness reached the 450-525 HV. The time of ageing at 600°C to reach hardness 600 HV was 15 seconds. No precipitation in specimen aged at 500°C for 60 s was found in TEM and HRTEM investigations. Deformation immediately after ageing intensifies the process of hardening caused by temporary increase of temperature and increase of dislocation density. The hardness of specimens aged for 30 s and then deformed at 480-550°C was similar to the hardness at peak aged conditions (480°C/4h) and reached 600-630 HV. Material produced in industrial trials of cold forward flow forming and following laboratory ageing was analyzed. Increase of hardness from 370 HV to 590-630 HV for specimens taken from thin walled flow formed tube as a result of ageing at 460-490°C for 30 minutes occurred.

PL

Przedstawiono wyniki badań procesu starzenia stali maraging w gatunku MS350 dla próbek nieodkształconych i odkształconych bezpośrednio po starzeniu. Przeprowadzono eksperymenty starzenia krótkotrwałego (15. 30 i 60 s) w temperaturze do 600°C. Stwierdzono, że po starzeniu w zakresie temperatury 480-500<,C w czasie 15-60 s bez odkształcenia, twardość osiągnęła 450-525 HV. Czas starzenia w temperaturze 600°C do osiągnięcia twardości 600 HV wynosił 15 s. Nie stwierdzono wydzieleń w próbkach starzonych w temperaturze 500°C przez 60 s w badaniach z zastosowaniem wysokorozdzielczego transmisyjnego mikroskopu elektronowego. Odkształcenie bezpośrednio po starzeniu intensyfikuje proces umacniania wydzieleniowego w skutek chwilowego wzrostu temperatury oraz wyrost u gęstości dyslokacji. Twardość próbek starzonych przez 30 s i odkształcanych w zakresie temperatury 480- 500“^ była zbliżona do twardości uzyskiwanej dla warunków starzenia w celu uzyskania twardości maksymalnej (480°C/4godz.) i wynosiła 600-630 HV. Przeprowadzono badania materiału wytwarzanego w próbach przemysłowych zgniatania obrotowego i starzonego w warunkach laboratoryjnych. Dla próbek pobranych z rury cienkościennej uzyskano wzrost twardości z 370 HV do 590-630 HV w wyniku starzenia w zakresie temperatury 460-490°C przez 30 minut.

11

Structural and phase analysis of CrAlSiN/DLC deposited by hybrid PVD/PACVD method

Lukaszkowicz K., Dobrzański L. A.

Inżynieria Materiałowa

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2013

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Vol. 34, nr 4

320--323

EN

The investigations concerned structural and phase analysis of CrAlSiN/DLC double-layer coating deposited by hybrid PVD/PACVD method on the X40CrMoV5-1 hot work tool steel substrate. The production process of double-layer coatings, such as hard nitride layer-low friction DLC layer, was carried out in the continuous mode, on a device fumished with technologies of lateral, rotating cathodes and central rotating cathode, within one technological process. The nano/microstructure, morphology, phase identiﬁcation and chemical state of the coating were analyzed by high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) respectively. The fractographic tests made with the electron scanning microscope allow to assert that the individual layers are deposited uniformly and tightly adhere to each other and to the substrate material. Morphology of the surface of fractures in the tested coating is characterized by a compact structure. HRTEM investigation shows an amorphous character of DLC layer. It was found that tested CrAlSiN layer has nanostructural character with ﬁne crystallites, while their average size is less than 10 nm. There is shown the character of a joint between an external low-friction DLC layer and a hard nanocrystalline nitride CrAlSiN layer as well as between the substrate and a CrAlSiN layer. The tests performed indicate that transition areas exist with a varied concentration of elements existing between the individual layers forming the transition zones. A low value of a relative relationship of oxygen to carbon concentration signiﬁes a high chemical quality of the produced DLC layer.

PL

Badania dotyczyły analizy strukturalnej i fazowej dwuwarstwowej powłoki CrAlSiN/DLC wytworzonej hybrydową metodą PVD/PACVD na podłożu ze stali narzędziowej do pracy na gorąco X40CrMoV5-1. Wytwarzanie powłok dwuwarstwowych typu twarda warstwa azotkowa-warstwa nisko- tarciowa DLC realizowano W cyklu ciągłym, na urządzeniu wyposażonym w technologie bocznych, obracających się katod oraz centralnej obrotowej katody, W jednym procesie technologicznym. Badania nano/mikrostruktury, morfologii powierzchni, analizy składu fazowego oraz stanu chemicznego pierwiastków wchodzących w skład badanych warstw wykonano odpowiednio za pomocą wysokorozdzielczej transmisyjnej mikroskopii elektronowej (HRTEM) i skaningowej mikroskopii elektronowej (SEM), mikroskopii sił atomowych (AFM), dyfrakcji rentgenowskiej (XRD) oraz spektroskopii fotoelektronów rentgenowskich (XPS). Wykonane badania fraktograﬁczne w skaningowym mikroskopię elektronowym pozwalają stwierdzić, że poszczególne warstwy są równomiernie nałożone i szczelnie przylegają do siebie oraz materiału podłoża. Morfologia powierzchni przełomów badanej powłoki charakteryzuje się zwartą budową. Wyniki badań uzyskane za pomocą transmisyjnej mikroskopii elektronowej wskazują na amorficzny charakter warstwy DLC. Stwierdzono, że warstwy CrAlSiN wykazują strukturę nanokrystaliczną o wielkości ziarna poniżej 10 nm. Przedstawiono charakter połączenia występujący pomiędzy zewnętrzną warstwą niskotarciową DLC a twardą nanokrystaliczną warstwą azotkową CrAlSiN, jak również pomiędzy materiałem podłoża a warstwą CrAlSiN. Wykonane badania wskazują na istnienie obszarów przejściowych o zmiennym stężeniu pierwiastków występujących pomiędzy poszczególnymi warstwami tworzącymi strefy przejściowe. Mała wartość względnego stężenia tlenu do węgla świadczy o wysokiej jakości chemicznej uzyskanej warstwy DLC.

12

Recognition and characterization of defects in GaN epilayers

Jezierska E., Borysiuk J.

Inżynieria Materiałowa

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2013

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Vol. 34, nr 4

277--282

EN

Using conventional and high resolution electron microscopy typical contrast was identiﬁed for the “a” pure edge threading dislocations in GaN layers grown on SiC and sapphire. Their atomic structure was shown to exhibit 5/7 atoms conﬁguration. The {1 2 10} stacking fault has two atomic conﬁgurations in wurtzite GaN with 1/2<10 1 1> and 1/6<20 2 3> displacement vectors. It originates from steps at SiC surface and it can form on a flat (0001) sapphire surface. In the investigated samples mainly Holt conﬁguration of inversion domains and zigzag boundaries were found. This conﬁguration is realized by inversion with displacement c/2. Different types of nanopipes were found on the cross-sectional GaN/Al2O3 specimens. Most of the observed nanopipes have hexagonal cross-section on planar view and the diameter in the range 5÷20 nm. Screw distortion around the nanopipes was conﬁrmed using Large-Angle Convergent-Beam Electron Diffraction (LACBED) images. Cubic-GaN inclusions were found as colonies of triangular pyramids with the hill of triangle towards SiC substrate. The appearance of second phase precipitates inside wurtzite GaN epilayer is associated with stacking mismatch boundaries and misoriented mosaic domains. The size of c-GaN inclusions is in the range 2÷16 nm with average lateral diameter near 5 nm.

PL

Krawędziowe dyslokacje typu ,,a” przebiegające na wskroś warstw epitak- sjalnych GaN/SiC zidentyﬁkowano na podstawie typowego kontrastu, stosując techniki konwencjonalne i wysokorozdzielczą mikroskopię elektronową. Określono atomową konﬁgurację rdzenia dyslokacji, jako układ 5/7 najbliższych atomów. Występujące w strukturze wurcytu błędy ułożenia {1 2 10} przyjmują w badanych warstwach epitaksjalnych GaN dwie konﬁgurację 0 różnych wektorach przemieszczenia 1/2<10 1 1> i 1/6<20 2 3>. Powstają one na skutek tworzenia stopni na powierzchni podłoża SiC lub na płaskich powierzchniach bazowych szaﬁru. Stwierdzono występowanie granic domen inwersyjnych i granic typu zig-zag o konﬁguracji charakteryzującej się złożeniem inwersji i przemieszczenia c/2 w kierunku osi heksagonalnej. W warstwach epitaksjalnych GaN/szaﬁr zaobserwowano nanorurki jako dyslokacje śmbowe o otwartym rdzeniu. Większość nanorurek na przekroju planarnym wykazywała kształt heksagonahiy i rozmiary w zakresie 5 ÷20 nm. Dystorsja śmbowa wokół nanorurek została potwierdzona za pomocą metody zbieżnej wiązki elektronów przy dużych kątach zbieżności (LACBED). W strukturze heksagonalnej GaN/SiC zaobserwowano obszary fazy o sieci regulamej c-GaN, jako kolonie o kształcie odwróconych piramidek o wielkości u podstawy 2÷16 nm, przy średniej wielkości 5 nm.

13

HRTEM observation of age-precipitation in Mg-Gd-Y alloys

Nakagawa D., Kawabata T., Ikeno S., Matsuda K.

Archives of Metallurgy and Materials

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2013

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Vol. 58, iss. 2

361--362

EN

Precipitation in Mg-Gd-Y alloys which have the different total amount of RE were investigated by HRTEM and SAED technique, and calculation of HRTEM images and electron density by first principles to understand the relationship between precipitation in these alloys and HRTEM images. The diffuse scattering by SAED was obtained in as-quenched samples in each alloy, and mono-layer zones have been confirmed by HRTEM observation. The atomic position just consisted of the RE and Mg columns show the black contrast, and the bright dots correspond to the space surrounding by the six Mg columns of hexagonal network with 0.18 nm. This is also corresponded the distribution of electron density of the cluster according to calculation by first principles.

PL

W stopach Mg-Gd-Y o różnej zawartości metali ziem rzadkich badano procesy wydzielania za pomocą technik HRTEM i SAED oraz symulowania obrazów HRTEM i gęstości elektronów przy użyciu pierwszych zasad w celu zrozumienia korelacji między wydzieleniami w tych stopach i obrazami HRTEM. W przesyconych próbkach we wszystkich stopach widoczne było na obrazach SAED rozpraszanie dyfuzyjne, a monowarstwowe strefy zostały potwierdzone podczas obserwacji HRTEM. Pozycje atomowe złozone tylko z kolumn atomów ziem rzadkich i Mg daja czarny kontrast, a jasne punkty odpowiadaja pozycjom otoczonym przez sześć kolumn Mg o sieci heksagonalnej o odległosci 0.18 nm. Odpowiada to również rozkładowi gęstości elektronowej klastra zgodnie z obliczeniami metodą pierwszych zasad.

14

Amorphous - nanocrystalline melt spun Al-Si-Ni based alloys modified with Cu and Zr

Kukuła-Kurzyniec A., Dutkiewicz J., Ochin P., Perrière L, Dłużewski P., Góral A.

Archives of Metallurgy and Materials

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2013

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Vol. 58, iss. 2

419--423

EN

In the present paper glass forming ability and structure of Al-Si-Ni based alloys were investigated. Three alloys starting from the ternary Al78Si12Ni10 [alloy 1], Al75Si12Ni8Zr5 [alloy 2] and Al73Si5Ni7Cu8Zr7 [alloy 3] were subjected to melt spinning process. The mean thickness of the obtained ribbons amounted between 25 and 40 μm. XRD and DSC studies showed predominantly amorphous structure of the ribbons. STEM and HRTEM methods confirmed participation of crystalline phase identified mainly as Al solid solution with the grain size near 10 nm. The mean microhardness [0.1N] of the ribbons was measured for alloys 1 - 3 respectively: 457 HV, 369 HV and 536 HV. The high value of hardness can be related to the presence of α-Al dispersoids in the amorphous matrix.

PL

W niniejszej pracy badano skłonność do tworzenia struktury szklistej oraz strukturę stopów na osnowie Al-Si-Ni. Trzy stopy zostały poddane procesowi odlewania na wirujący walec miedziany: Al78Si12Ni10 [stop 1], Al75Si12Ni8Zr5 [stop 2] oraz Al73Si5Ni7Cu8Zr7 [stop 3]. Grubość otrzymanych taśm wynosiła pomiędzy 25 a 40 μm. Badania rentgenowskie oraz kalorymetryczne taśm wykazały, że ich struktura jest głównie amorficzna, co potwierdziły metody STEM oraz HRTEM, ujawniając również wydzielenia krystaliczne zidentyfikowane jako roztwór aluminium o wielkości ziarna bliskiej 10 nm. Średnia mikrotwardość [0,1 HV] wyniosła odpowiednio dla stopów 1-3: 457 HV, 369 HV oraz 536 HV. Tak wysoka twardość jest przypuszczalnie związana z obecnością w strukturze amorficznej wydzieleń roztworu α-Al.

15

Ultra-high crystallinity millimeter long multiwall carbon nanotubes fabricated by mechanothermal method

Manafi S. A., Rahimipour M. R., Soltanmoradi A.

Materials Science Poland

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2012

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Vol. 30, No. 3

226--230

EN

In this work, multi-walled carbon nanotubes (MWCNTs) with ultra-high crystalline structure have been prepared by mechanothermal (MT) method. The novel super nanostructure is introduced for the first time as an extraordinary fullerene-carbon based material which, due to its special electronic and mechanical properties, can be used to construct unique building blocks for nanoengineering. Initially, high ultra-active graphite powder has been obtained by mechanical activation under Ar atmosphere. Finally, the mechanically activated product is heat-treated at 1350 °C for 3-4 h under an Ar gas flow. However, the crystallite size and crystallinity degree of the MWCNTs increased with the increase in annealing temperature.

16

Ball milling amorphization and consolidation of NiTiZrNb and NiNbTiZrCoCu alloys

Dutkiewicz J., Lityńska-Dobrzyńska L., Maziarz W., Czeppe T., Góral A., Grzonka J.

Inżynieria Materiałowa

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2010

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Vol. 31, nr 3

502-505

EN

Two compositions of nickel rich alloys containing Ni49.5Ti20.5Nb15Zr15 and Ni53Nb20Ti10Zr8Co5Cu3 (in at. %) were ball milled in a high energy planetary mill for 40 hours starting from pure elements. DSC measurements have shown almost complete amorphization with a high intensity exothermic crystallization peak at 590°C for the first composition and at 620°C for the second one. The X-ray diffraction confirmed amophization of milled powders showing only broad amorphous hallow. HRTEM studies allowed to identify nanocrystalline inclusions in milled powders of size below 5 nm, mostly of Ni7Ti2 phase, however in a few cases Ni30Ti9Zr or Ni2Zr phases can also be matched to a distance and mutual angles of fringes in high resolution micrographs. Hot pressing in vacuum of the amorphous powders at temperature just below crystallization allowed to consolidate powders at very low porosity below 1%. The average hardness of the first alloy was near 820 HV and that of the other one was slightly lower, however at low ductility. The HRTEM studies shown nanocrystalline particles of size up to 30 nm with the same tendency as in ball milled powders identified as nickel rich phases.

PL

Dwa stopy zawierające Ni49,5Ti20,5Nb15Zr15 i Ni53Nb20Ti10Zr8Co5Cu3 (w % at.) mielono w wysokoenergetycznym planetarnym młynku kulowym przez 40 godzin, rozpoczynając od czystych składników. Badania mikrokalorymetryczne wykazały silne maksima od krystalizacji w temperaturze odpowiednio 590°C i 620°C dla pierwszego i drugiego stopu. Badania metodą dyfrakcji rentgenowskiej potwierdziły prawie wyłączną obecność fazy amorficznej w mielonych proszkach, jakkolwiek badania metodą wysokorozdzielczej transmisyjnej mikroskopii elektronowej HRTEM pozwoliły na identyfikację cząstek nanokrystalicznych o wielkości do 5 nm fazy Ni7Ti2 oraz faz Ni30Ti9Zr lub Ni2Zr na podstawie odległości i kątów pomiędzy płaszczyznami atomowymi. Prasowanie na gorąco mielonych proszków w temperaturze poniżej krystalizacji pozwoliło na ich konsolidację przy niskiej porowatości (poniżej 1%) o twardości około 820 HV. Badania HRTEM pozwoliły na stwierdzenie wzrostu cząstek nanokrystalicznych do wielkości około 30 nm z tendencją tworzenia faz wysokoniklowych.

17

Morfologia powierzchni międzyfazowych w wielowarstwowych strukturach periodycznych AlGaAs/GaAs

Barańska A., Kosiel K., Kubacka-Traczyk J., Bugajski M., Pasternak I., Płociński T., Kurzydłowski K.

Elektronika : konstrukcje, technologie, zastosowania

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2010

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Vol. 51, nr 10

112-115

PL

Artykuł przedstawia wyniki badań morfologii powierzchni międzyfazowych heterostruktur epitaksjalnych AlGaAs/GaAs. Struktury zostały wykonane metodą epitaksji z wiązek molekularnych (MBE). Charakteryzację struktur przeprowadzono stosując mikroskopię sił atomowych (AFM) oraz wysokorozdzielczą transmisyjną mikroskopię elektronową (HRTEM). Badano warstwy GaAs/GaAs, AlGaAs/GaAs oraz wielowarstwowe struktury periodyczne AlGaAs/GaAs, osadzane na podłożach o orientacji (100).

EN

The paper presents some results of investigation of interfacial morphology in AlGaAs/GaAs epitaxial heterostructures. The structures were grown by molecular beam epitaxy (MBE). Their characterisation was performed by atomie force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM). The simple GaAs/GaAs, AlGaAs/GaAs as well as multilayer, periodic AlGaAs/GaAs heterostructures deposited on (100) GaAs substrates were studied.

18

HR TEM examinations of nanodiamond particles for biomedical application

Mitura K.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 37, nr 2

317-322

EN

Purpose: The aim of the study is an analysis of a different type of nano-diamond powders on HR TEM (material characterisation, the normal distribution of grain size). These nano-powders were used in many biological researches and each of them had a special biological activity. Comparison between the material and biological properties of diamond powders answered many questions about the chemical and physical reactions on a boundary: diamond surface – living organism. Design/methodology/approach: In this work we used cytotoxicity assays using MTT test and HR TEM examinations. We examined the nanodiamond particles manufactured by detonation method, RF/MW PACVD method, RF PACVD method, pure diamond from De Beers Company and graphite powder as a control. Findings: In this subject the material characterisation of diamond powders are known but we examined a different type of powders and we manufactured some of these nanopowders in our laboratory. Practical implications: Nanocrystalline Diamond Coatings have many applications in various fields of medicine. Nanodiamond Particles are an extended surface of diamond powder. Biological research with endothelial and lung cancer cells are the introduction to application in human’s treatment. Originality/value: There are in vitro examinations with bioactive biomaterial. Nanodiamond particles have a very high bioactivity on cell level and inhibit cancerogenesis.

19

ABC nanotechnologii. Cz. III. Wybrane metody pomiaru wielkości nanomateriałów

Szatkowski A.

Laboratorium - Przegląd Ogólnopolski

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2008

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nr 10

19--21

PL

To już trzeci artykuł z serii ABC nanotechnologii. W poprzednich artykułach znalazły się podstawowe informacje na temat nanotechnologii jako nowej dziedziny nauki, przybliżono także różne rodzaje nanostruktur wraz z krótką charakterystyką wybranych nanomateriałów. Tym razem artykuł zawiera kilka informacji na temat badania wielkości nanocząstek.

EN

lt is the third article from the ABC of nanotechnology series. The previous articles have presented information on nanotechnology as a new field of science, the main differences between groups of nanomaterials and also a characteristic of the chosen groups. This article contains information about the measurements of the nanoparticle size.

20

FMR study of nanocarbon materials obtained by carburisation of nanocrystalline iron

Narkiewicz U., Arabczyk W., Pełech I., Guskos N., Typek J., Maryniak M., Woźniak M. J., Matysiak H., Kurzydłowski K. J.

Materials Science Poland

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2006

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Vol. 24, No. 4

1067--1075

EN

Samples of nanocrystalline iron were carburised with ethylene and next reduced with hydrogen. Both carburisation and reduction were monitored by the thermogravimetry. The obtained samples were characterised using X-ray diffraction, high-resolution transmission electron microscopy and ferromagnetic resonance. The samples after carburisation contained cementite (Fe3C) and carbon deposit (nanofibres and nanotubes). As the result of reduction with hydrogen at 450 or 500 °C cementite was reduced to iron. A major part of carbon was also hydrogenated, only thin carbon nanotubes remained. The FMR spectra of the prepared samples were recorded at room temperature. The sample after carburisation has shown a wide FMR line with weak intensity while the resonance field has been shifted to lower magnetic field. This spectrum has been attributed to the presence of cementite. The FMR lines corresponding to samples after reduction are more intense and are connected with the presence of alfa-Fe nanoparticle conglomerates.