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1

Influence of Milling Time on Formation of NiTi Alloy Produced by High-Energy Ball Milling

Salwa P., Goryczka T.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 4

1301--1307

EN

Mixture of nickel and titanium powders were milled in planetary mill under argon atmosphere for 100 hours at room temperature. Every 10 hours the structure, morphology and chemical composition was studied by X-ray diffraction method (XRD), scanning electron microscope (SEM) as well as electron transmission microscope (TEM). Analysis revealed that elongation of milling time caused alloying of the elements. After 100 hours of milling the powders was in nanocrystalline and an amorphous state. Also extending of milling time affected the crystal size and microstrains of the alloying elements as well as the newly formed alloy. Crystallization of amorphous alloys proceeds above 600°C. In consequence, the alloy (at room temperature) consisted of mixture of the B2 parent phase and a small amount of the B19’ martensite. Dependently on the milling time and followed crystallization the NiTi alloy can be received in a form of the powder with average crystallite size from 1,5 up to 4 nm.

2

Influence of Milling Time on Formation of NiTi Alloy Produced by High-Energy Ball Milling

Salwa P., Goryczka T.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 3

1017--1022

EN

Mixture of nickel and titanium powders were milled in planetary mill under argon atmosphere for 100 hours at room temperature. Every 10 hours the structure, morphology and chemical composition was studied by X-ray diffraction method (XRD), scanning electron microscope (SEM) as well as electron transmission microscope (TEM). Analysis revealed that elongation of milling time caused alloying of the elements. After 100 hours of milling the powders was in nanocrystalline and an amorphous state. Also extending of milling time affected the crystal size and microstrains of the alloying elements as well as the newly formed alloy. Crystallization of amorphous alloys proceeds above 600°C. In consequence, the alloy (at room temperature) consisted of mixture of the B2 parent phase and a small amount of the B19' martensite. Dependently on the milling time and followed crystallization the NiTi alloy can be received in a form of the powder with average crystallite size from 1,5 up to 4 nm.

3

Synthesis of NiO nanoparticles by sol-gel technique

Kayani Z. N., Butt M. Z., Riaz S., Naseem S.

Materials Science Poland

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2018

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Vol. 36, No. 4

547--552

EN

NiO nanoparticles were fabricated by sol-gel route using ammonium hydroxide and nickel nitrate as precursors. The NiO nanoparticles were calcinated at 400 °C and 1000 °C. The nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), thermogravimetry analysis/differential thermal analysis (TGA/DTA). The structural properties were evaluated by X-ray diffraction (XRD). XRD confirmed the formation of well-crystallized and high purity NiO phase. The XRD showed that the peaks were sharpened and the crystallite size increased as the calcination temperature increased. The average crystallite size ranged from 12 nm to 20 nm, when calcined at temperatures 400 °C and 1000 °C, respectively. Fourier transform infrared spectroscopy (FT-IR) revealed the chemical composition and confirmed the formation of NiO nanoparticles. The nanoparticles showed paramagnetic behavior.

4

Properties and Structure of Nanocrystalline Layers Obtained by Manual Metal Arc Welding (MMA)

Górka J., Czupryński A., Adamiak M.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 3

1479--1484

EN

The present paper is the result of the investigations of the properties and structure of nanocrystalline layers deposited from iron-based nanoalloy on steel S355N substrate by manual metal arc welding method (MMA). In the process of welding a 100 A current intensity was used with desiccation preheating at 80°C while maintaining the interpass temperature at range of 200°C. The resultant deposit welds were subjected to macro and microscopic metallographic examination, X-ray phase analyses and crystallite size was analyzed by X-ray diffractometry (XRD), additionally EDX chemical composition analysis of precipitates during scanning electron microscopy was performed. Working properties of the obtained nanocrystalline deposit welds were evaluated based on hardness and metal-to-mineral abrasive wear. The results of the deposit welds working properties measurements were compared with the properties of wear resistant steel HARDOX 400 type used as the reference material.

5

Catalyst free growth of single-crystalline bismuth nanorods by closed space sublimation technique

Usman W., Maqsood A.

Materials Science Poland

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2015

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Vol. 33, No. 2

381--390

EN

In the present study, bismuth (Bi) thin films having thickness of 335 nm have been deposited onto a glass substrate by closed space sublimation (CSS) technique. Besides this, spontaneous growth of Bi nanorods has also been investigated for the first time, without template and catalyst assistance in a substrate temperature range of 380 to 430 degrees C using CSS technique. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to investigate microstructure, morphology and roughness of the Bi nanorods. The diameter and length ranges of Bi nanorods were 80 to 400 nm and 3 to 5 mu m, respectively. Moreover, they exhibited a rhombohedral structure with a dominant peak indexed at (012), (104), and (110). The mass percentage of Bi, determined by energy dispersive X-ray (EDX), was 99.93 %. The studies of electrical resistivity, Hall coefficient, magnetoresistivity, hole mobility and carrier concentration of Bi thin films were performed at 300 to 350 K and the electrical properties were found to be a function of temperature. The basic aim was to investigate the spectacular evolution of Bi nanostructures on as-deposited thin films and effects of thickness on their structural, electrical and dielectric properties. Detailed examination of SEM micrographs eliminated all other growth modes except self-catalytic tip growth by Vapor-Solid (VS) growth process which is believed to provide the driving force for spontaneous nanorod growth at high substrate temperature. Deposition of thinner Bi films provided a new possibility for fabrication of Bi nanorods of high quality.

6

Effect Of Heat-Treatment On Microstructure And Magnetic Properties Of Nanocrystallized Mn-Zn Ferrite Powders

Lee W. H., Hong C. S., Chang S. Y.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1347--1350

EN

The initial ferrite powders were subjected to high energy ball milling at 300rpm for 3h, and subsequently heat-treated at 573-1273K for 1h. Based on the observation of microstructure and measurement of magnetic properties, the heat-treatment effect was investigated. The size of initial powders was approximately 70μm. After milling, the powders with approximately 230nm in size were obtained, which were composed of the nano-sized particles of approximately 15nm in size. The milled powders became larger to approximately 550nm after heat-treatment at 973K. In addition, the size of particles increased to approximately 120nm with increasing temperature up to 973K. The coercivity of initial powders was almost unchanged after milling, whereas the saturation magnetization increased. As the heat-treatment temperature increased, the saturation magnetization gradually increased and the maximum coercivity was obtained at 773K.

7

Synthesis of Ag-ZnO composites via ball milling and hot pressing processes

Ardestani M., Zakeri M, Nayyeri M J, Babollhavaejie M R

Materials Science Poland

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2014

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Vol. 32, No. 1

121--125

EN

Ag – 8 wt. % ZnO composites were synthesized by ball milling, heat treating and hot pressing of silver and zinc oxide powder mixtures. The crystalline size and microstrain of the milled powders before and after heat treatment were determined by Debye-Scherrer andWilliamson-Hall methods. It was shown that heat treatment resulted in decrease of microstrain and increase in the crystallite size of the milled powders. The effect of uniaxial pressure magnitude and duration of hot pressing at 550 °C on the final density of the powder compacts were investigated. The results showed that both plastic flow and atomic diffusion mechanisms affected densification of the composite powders during the hot pressing process. However, the latter one had more effective role on the density of the hot-pressed samples. The synthesized composites showed homogenous microstructure with relatively high density and hardness.

8

Changes of crystallite sizes in the oxides layer determined on the basis of X-ray diffraction lines broadening

Gwoździk M., Nitkiewicz Z.

Inżynieria Materiałowa

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2014

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Vol. 35, nr 2

136--138

EN

The paper contains results of the studies on X-ray diffraction analysis XRD (studying the phase composition, crystallite sizes and lattice deformations) of oxide layers on 10CrMo9-10 steel, operated for a long time at an elevated temperature (T = 575°C, t = 100 000 h). X-ray studies were carried out on the inner surface of a tube, and then the layer surface was polished down and the diffraction measurements were performed again to determine crystallite size in oxide layers. The broadening of a diffraction line caused by a small size of crystallites is expressed by the Scherrer relationship. It has been found that a layer of magnetite Fe3O4 is formed as a result of longterm operation of the studied steel at the temperature of 575°C. The created layer featured a diversified morphology of magnetite, which is related inter alia to the crystallites size, which then can affect the cleavage.

PL

Praca zawiera wyniki badań dotyczących rentgenowskiej analizy dyfrakcyjnej XRD (badanie składu fazowego, wielkości krystalitów i odkształceń sieciowych) warstw tlenkowych powstałych na stali 10CrMo9-10 długotrwale eksploatowanej w podwyższonej temperaturze (T = 575°C, t = 100 000 h). Badania rentgenograficzne przeprowadzono na powierzchni wewnętrznej rury, następnie powierzchnię warstwy spolerowywano i ponownie wykonywano pomiary dyfrakcyjne w celu określenia wielkości krystalitów w warstwie tlenkowej. Poszerzenie linii dyfrakcyjnej spowodowane małą wielkością krystalitów zostało wyrażone zależnością Scherrera. Stwierdzono, że w wyniku długotrwałej eksploatacji badanej stali w temperaturze 575°C powstaje warstwa magnetytu Fe3O4. Powstała warstwa charakteryzowała się zróżnicowaną morfologią magnetytu, co jest związane m.in. z wielkością krystalitów, które z kolei mogą wpływać na łupliwość.

9

Influence of RCS process on the structure and mechanical properties of CuSn6 alloy

Kwaśny W., Nuckowski P., Rdzawski Z., Głuchowski W.

Archives of Materials Science and Engineering

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2013

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Vol. 62, nr 2

60--66

EN

Purpose: The goal of the study is try to find the influence of plastic deformation using the RCS (repetitive corrugation and straightening) process on the structure and mechanical properties of CuSn6 alloy. The influence of process parameters on the above property were investigated. Obtained results were correlated with the results obtained for alloy subjected to cold rolling. Design/methodology/approach: This study was aimed to investigate structure and mechanical properties non annealed strip of CuSn6 alloy, cold-rolled and the tape subjected to intensive plastic deformation using the RCS method (repetitive corrugation and straightening). Findings: Research have shown increase compressive stresses and tensile strength in material after RCS process compared to classic rolled. Crystallite size measurement confirmed the presence of nano-scale structures in the studied materials after deformation by RCS process. The used method of plastic deformation is promising for development materials with improved properties. Research limitations/implications: The research was carried out on samples, not on final elements. Practical implications: Research is moving towards the development of the materials with finest microstructure, known as ultra-fine-grained materials with improved properties, compared to currently known materials. Originality/value: This paper presents the results of study of the structure and mechanical properties CuSn6 alloy deformed in the RCS (repetitive corrugation and straightening) process.

10

Effect of calcination temperature on photocatalytic activity of TiO2. Photodecomposition of mono- and polyazo dyes in water

Mozia S.

Polish Journal of Chemical Technology

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2008

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Vol. 10, nr 3

42-49

EN

The presented studies have focused on the influence of TiO2 properties, such as crystalline phase, crystallite size and surface area, on the effectiveness of degradation of azo dyes in water under UV irradiation. Two monoazo dyes: Acid Red 18 (AR18, C20H11N2Na3O10S3) and Acid Yellow 36 (AY36, C18H14N3NaO3S), and one polyazo dye Direct Green 99 (DG99, C44H28N12Na4O14S4) were applied as model compounds. The photocatalysts were prepared from a crude titanium dioxide obtained directly from the production line (sulfate technology) at the Chemical Factory "Police" (Poland). The crude TiO2 was calcinated in air for 1-4h at the temperatures ranging from 600 to 800°C. The BET specific surface area of TiO2 decreased gradually with increasing the calcination temperature. The crude TiO2 exhibited specific surface area of 277 m2/g. In case of the catalysts heated at 600, 700 and 800°C the BET surface area amounted to 62.3-53.3, 33.4-26.8 and 8.9-8.3 m2/g, for the calcination time of 1-4h, respectively. The crystallite size of anatase increased with increasing heat treatment temperature and ranged from 19 to 53 nm, for the temperatures of 600-800°C, respectively. The catalysts annealed at 600 and 700°C contained primarily anatase phase (94-97%), whereas the photocatalysts heated at 800°C were composed mainly of rutile (97-99%). The highest effectiveness of azo dyes degradation was obtained in case of the photocatalyst calcinated for 1h at 700°C. The photocatalyst was composed mainly of anatase (97%) with crystallite size of 27 nm. The most effectively photodegraded was AR18, having the molecular weight of 640.4 g/mol. The most difficult to degrade was AY36 exhibiting the lowest molecular weight from all the dyes used (375.4 g/mol).

11

Fabrication of nano-structured materials by high-pressure sintering

Czepelak M., Staszewski M., Wrona A., Lis M., Osadnik M.

Archives of Materials Science and Engineering

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2008

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Vol. 30, nr 2

109-112

EN

Purpose: The aim of this work was to fabricate nanocrystalline powders and high-density bulk materials using a sintering method with limited grain growth so as to maintain nanocrystalline structure of the materials also after sintering. Design/methodology/approach: The size of crystallites and physical properties of the obtained nanocrystalline powders and sinters made from these powders were examined. The studied materials were pure copper and the following powders: Cu+1%WC, Cu+3%WC, Cu+3%AlNi and AlNi. The technology for preparation of nano-structured powders was used, which included milling the powders in ball mills and their sintering in a pressing furnace. Findings: It was found that the objective of this work can be achieved provided that high-pressure sintering is used, in which the stages of compacting and sintering proceed simultaneously over a short period of time. Research limitations/implications: It is recommended to perform further studies aimed at checking the possibility of using the proposed method of nanomaterials fabrication in the case of the materials with other chemical composition. Practical implications: This work broadens possibilities of metal powder sintering technology by fabrication of bulk nanocrystalline materials. Originality/value: The results from his work shall be useful in determining conditions for fabrication of nanocrystalline or sub-microcrystalline materials by the sintering method.

12

Thermomagnetic behavior and microstructure of a rapidly quenched Nd14Fe79B7 alloy

Cosovic V., Talijan N., Stajic-Trosic J., Grujic A., Zivkovic D., Zak T.

Archives of Materials Science

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2007

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Vol. 28, nr 1-4

20-24

EN

Changes in the phase composition and crystallite size, as well as changes in the magnetic behavior of overstoichiometric Nd14Fe79B7 alloy (32 mass% Nd), caused by the thermomagnetic measurements (TM), were observed in regard to the optimal magnetic state of this alloy. In the optimized magnetic state, the hard magnetic phase Nd2Fe14B is identified as the primary phase (up to 95 mass %), with a mean crystallite size about 60 nm, as determined by XRD analysis and Transmission electron microscopy (TEM). The derogation of magnetic properties after TM is due to decreased amount of Nd2Fe14B phase, the formation of Nd2O3 and different Fe(O)B phases, as well as an increase in the mean crystallite size (e.g. Nd2Fe14B . 95 nm).

13

Określanie wielkości krystalitów i odkształceń sieciowych w nanokompozycie NiAl-Al2O3 na podstawie poszerzenia rentgenowskich linii dyfrakcyjnych

Oleszak D., Olszyna A.

Kompozyty

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2004

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R. 4, nr 11

284-287

PL

Nanokompozyt NiAl-Al2O3 wytworzono metodą reaktywnego mielenia, wychodząc z mieszaniny NiO i Al. Przedłużone mielenie do 40 h pozwoliło uzyskać znaczne poszerzenie rejestrowanych rentgenowskich linii dyfrakcyjnych obu faz, sugerujące nanokrystaliczny charakter materiału. Dokonano obliczeń wielkości krystalitów i zniekształceń sieciowych na podstawie poszerzenia rentgenowskich linii dyfrakcyjnych, zakładając różną postać funkcji aproksymacyjnych, opisujących profil rejestrowanych linii (Cauchy, Gauss). Obliczone różnymi metodami wielkości krystalitów i odkształceń sieciowych w Al2jO3 zawierały się odpowiednio w granicach 27-58 nm oraz 0,3-0,48%. W przypadku NiAl uzyskano wielkości z przedziału 13-29 nm oraz 0,29-0,77 %, obarczone jednak bardzo dużym błędem z powodu anizotropowego charakteru fazy NiAl.

EN

Nanostructured materials are intensively studied due to their good properties, in many cases better than properties of their conventional polycrystalline counterparts, exhibiting micrometer-range grains. Nanocrystalline materials are fabricated by different techniques, including mechanical alloying or reactive milling. The resulting powders usually have particle size of several micrometers, but they consist of nanometric crystallites. X-ray diffraction seems to be a simple technique for determination of crystallite size and lattice strain from the broadening of the diffraction lines. The aim of this work was to determine crystallite size and lattice strain of nickel aluminide and alumina. Both phases were formed during reactive milling of NiO+AI powder mixture. The average crystallite size and lattice strain were calculated from X-ray line broadening, applying different profiles of diffraction lines. The first method assumes that diffraction line broadening from microstructure refinement and that arising from strain are both described by Cauchy function. This approach is known as Williamson-Hall method. In the second method both contributions are of Gauss type. Finally, the last one asumes that size-broadening is Cauchy type, while strain induced broadening is Gaussian. The obtained values of crystallite size and lattice strain for alumina were in the range 27-58 nm and 0.3-0.48%, respectively, depending on the method of calculation. For all methods the correlation coefficient of fitting was reasonable. In the case of NiAl the calculated values of crystallite size and lattice strain were in the range 13-29 nm and 0.29-0.77%, respectively, depending on the calculation method. However, significant scattering of experimental data was observed due to the anisotropy of this compound. As a consequence, the fitting parameters were rather poor.

14

Struktura stopów Ni-Mo otrzymanych elektrolitycznie

Łągiewka E., Budniok A., Niedbała J.

Archiwum Nauki o Materiałach

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2002

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T. 23, nr 2

137-150

PL

W pracy określono skład fazowy, stałą sieciową, wielkość krystalitów, zniekształceń sieciowych i gęstości błędów ułożenia w elektrolitycznych warstwach stopu Ni-Mo. Warstwy stopu o grubościach około 30-40 mikrometrów otrzymano z opracowanego składu kąpieli cytrynianowej w zakresie gęstości prądu j=2,5-300 mA/cm kwadratowy, w temperaturze pokojowej. Metodami rentgenowskiej analizy strukturalnej wykazano, że są to jednofazowe roztwory stałe molibdenu w niklu (faza alfa). Rozpuszczalność molibdenu w roztworze na osnowie niklu rośnie wraz z gęstością prądu osadzania. Maksymalną rozpuszczalność molibdenu w niklu, która wynosi 23% at. uzyskano w stopach otrzymywanych przy gęstości prądu j=300 mA/cm kwadratowy. Wszystkie otrzymane stopy są nanokrystaliczne o wielkości krystalitów w zakresie 3-60 nm. Gęstość błędów ułożenia w stopach i wielkość zniekształceń II rodzaju wzrasta wraz z gęstością prądu osadzania stopu. Powierzchnia stopów ma charakter wysepkowy, którego topografia wraz z gęstością prądu osadzania stopów staje się coraz bardziej rozwinięta.

EN

Phase composition, lattice constant, crystallite size, lattice distortion and stacking fault densities in electrolytic layers of Ni-Mo alloys were determined. Alloys layers of 30-40 micrometers thickness were obtained from a prepared citrate bath of a specific composition in the current density range 2.5-300 mA/square cm at room temperature. From X-ray structure analysis it was found that they constitute one-phase solid solutions of molybdenum in nickel (alpha-phase). Solubility of molybdenum in solid solution with nickel increases with the increase of current density of electrodeposition. Maximum solubility of molybdenum in nickel equal to 23 at.% was obtained for alloy deposited at current density 300 mA/square cm. All obtained alloys are nanocrystalline with crystallite size of the range 3-60 nm. Stacking fault density and the size of lattice distortions increase with current density of alloy deposition. Surface of alloys is of island type and their morphology becomes more and more unfolded with the increase of current density of alloy deposition.