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1

Deformation Mechanisms and Fracture of Ni-Based Metallic Glasses

Lesz S., Griner S., Nowosielski R.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

791--796

EN

The cracking of materials and fracture surface is of great practical and academic importance. Over the last few years the development of the fractography of crystalline alloys resulted in a useful tool for the prediction or failure analysis. Many attempts have been made to observe cracks using optical microscopy, X-ray topography and transmission electron microscopy (TEM). Of these techniques, the resolution of optical microscopy and X-ray topography is too poor. By contrast, the resolution of TEM is high enough for detailed information to be obtained. However, in order to apply TEM observations, a thin foil specimen must be prepared, and it is usually extremely difficult to prepare such a specimen from a pre-selected region containing a crack. In the present work, deformation mechanisms fracture surfaces of Ni-based metallic glass samples have been studied by specially designed experiments. In order to study the deformation mechanisms and fracture the Ni-based metallic glasses have been investigated in the tensile test. The structure and fracture surfaces after the decohesion process in tensile tests were observed using transmission electron microscope (TEM) and scanning electron microscope (SEM), respectively. The studies of structure were performed on thin foils. Moreover the investigated tape was subjected to a banding test. Then, the tape was straightened and the thin foil from the area of maximum strain was prepared. This thin foil sample was deformed before the TEM investigation to obtain local tears.

2

Analiza możliwości oceny procesu pełzania stali X12CrMoWVNbN10-1-1 na podstawie szumu Barkhausena

Roskosz M., Fryczowski K., Griner S., Katunin A.

Przegląd Spawalnictwa

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2014

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R. 86, nr 11

35--40

PL

Przeprowadzono pomiary polowego efektu Barkhausena oraz pętli histerezy na cylindrycznych próbkach stali X12CrMoWVNbN10-1-1 średnicy 4 i długości 15 mm. Analizowano zmiany wielkości ilościowo opisujących badane efekty pomiędzy próbkami w stanie dostawy i po pełzaniu. Szukano takich wielkości magnetycznych, dla których wpływ zmian własności mechanicznych i mikrostruktury, zachodzących wskutek procesu pełzania, jest najbardziej widoczny. Dla polowego efektu Barkhausena procesy pełzania stali X12CrMoWVNbN10-1-1 powodują wzrost maksymalnej amplitudy składowych widma FFT oraz wzrost energii szumu Barkhausena. Analizując pętlę histerezy, stwierdzono spadki pola koercji po procesie pełzania. Analiza falkowa pokazała, że sygnały dla próbek w stanie dostawy cechują się większą regularnością, niż sygnały dla próbek po pełzaniu. Proces pełzania powoduje pojawienie się impulsów o niższych częstotliwościach, które nie występują dla próbek w stanie dostawy. Stwierdzone zmiany parametrów magnetycznych są podstawą do prowadzenia dalszych badań wpływu procesów pełzania na ich zmiany. Końcowym celem tych badań jest określenie korelacji pomiędzy zmianami wartości parametrów magnetycznych a stopniem zaawansowania procesu pełzania.

EN

The Barkhausen effect and the hysteresis loop were measured on 15 mm long cylindrical X12CrMoWVNbN10-1-1 steel specimens with a diameter of 4 mm. An analysis was conducted of the changes that describe the effects under analysis quantitatively. “New” specimens (in the as-delivered state) and post-creep specimens (destroyed due to creep) were compared. The aim was to find magnetic quantities for which the impact of creep-related changes in the mechanical properties and microstructure is the most visible. For the Barkhausen effect, the steel X12CrMoWVNbN10-1-1 creep processes result in a rise in the maximum value of the amplitude of the components of the FFT spectrum and the Barkhausen noise energy. Analyzing the hysteresis loop, drops in coercivity were found after the creep process was completed. The results of the wavelet analysis showed that the as-delivered state specimens signals are more regular than for post-creep specimens. Creep process causes the appearance of the low-frequency pulses which are not present in the as-delivered state specimens. The results of the testing are the basis for further research on the impact of creep processes on changes in magnetic properties. The ultimate object of the research is to determine the correlations between changes in values of magnetic parameters and the progress of creep.

3

Heterogeneity of mechanical properties and fractures of Co-based metallic glass in a low-temperature thermal activation process

Griner S., Spilka M., Kania A.

Journal of Achievements in Materials and Manufacturing Engineering

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2014

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Vol. 66, nr 2

53--60

EN

Purpose: The paper presents the changes of mechanical properties and the fractures of Co70.5Fe2.5Mn2Mo1Si9B15 metallic glass ribbons after a low-temperature activation process. Design/methodology/approach: The studied alloy was fabricated by continuous casting of the alloy stream on a turning wheel. The plastic properties were determined using the bend test. The investigations of unit cracking energy using the “tearing” test on the testing machine were carried out. The structure testing in transmission electron microscope and the static tensile test on the Instron testing machine were also carried out. Findings: The studies for 5 samples and for 2 ribbon sides were carried out. The highest plasticity occurred after annealing at 200°C for 1 h. The differences of mechanical properties in a function of a cross section of the ribbon were also presented. Practical implications: Despite the occurrence of heterogeneity of properties on the thickness of metallic glass ribbon the essential meaning have the averaging properties of a product which decided about possibility of practical application. Originality/value: In the article there was found that studied samples obtain different plasticity and different value of the yield point in the different bending methods.

4

Fabrication of screens for electromagnetic fields shielding with threats analysis at the position

Spilka M., Kania A., Griner S.

Journal of Achievements in Materials and Manufacturing Engineering

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2014

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Vol. 62, nr 1

38--44

EN

Purpose: The aim of this article is to pay attention on the necessary of protection of the people and devices from the harmful electromagnetic radiation. The special role play the screens (materials or systems) for shielding which have a very diversified construction depending on the frequency of electromagnetic fields. Design/methodology/approach: In the paper a problem of electromagnetic fields shielding was presented. Moreover, the occupational risk assessment at the vacuum sublimation position was showed. Findings: The screening methods and materials used for screens were discussed. The threats occurring at the vacuum sublimation position and the preventive actions decreasing the risk level were presented. Research limitations/implications: The paper presents the one of the methods for screens fabrication – vacuum sublimation in a simple laboratory vacuum sublimation equipment. The structure testing and investigation of thickness of fabricated screen (constructed from four layers: aluminum – polypropylene – aluminum – metallic glass of Metglas type) were carried out. The occupational risk assessment was made by three-stage scale method according to PN-N-18002 standard. Practical implications: The results of microscopic observation of fabricated material system unequivocally reject the vacuum sublimation method using a laboratory vacuum sublimation equipment for the screens fabrication. Originality/value: In the article the different kinds of threats occurring at the vacuum sublimation position were presented. The various preventive actions were proposed.

5

Analiza możliwości oceny stopnia deformacji plastycznej stali austenitycznych metodą magnetycznej pamięci metalu

Roskosz M., Griner S., Sosnowski P.

Przegląd Spawalnictwa

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2013

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R. 85, nr 12

130--135

PL

Celem badań była analiza możliwości identyfikacji obszarów odkształconych plastycznie oraz ilościowej oceny stopnia deformacji plastycznej stali austenitycznych na podstawie pomiarów własnego magnetycznego pola rozproszenia WMPR standardowymi przyrządami stosowanymi w metodzie MPM. Przedstawiono wyniki pomiarów WMPR próbek z dwóch stali austenitycznych X15CrNi- Si20-12 i X2CrNi18-9 o różnych stopniach trwałej deformacji. Stwierdzono, że dla stali X15CrNiSi20-12 nie występują, mierzalne standardową aparaturą metody MPM, zmiany WMPR. W przypadku stali X2CrNi18-9 obszary trwale odkształcone wyróżniają się na rozkładach składowych WMPR i jest możliwa ich identyfikacja. Opracowano ilościowe relacje pomiędzy stopniem deformacji plastycznej a wartościami gradientów. Niestety, jednoznaczne określenie stopnia deformacji możliwe jest dopiero dla dużych jej wartości, bo dopiero powyżej 10% odkształcenia trwałego relacje stają się jednoznaczne. Ogranicza to bardzo istotnie możliwość jej praktycznego zastosowania.

EN

The aim of the research was to analyze the possibility of identification of areas featuring plastic strain and quantitative evaluation of the degree of plastic deformation of austenitic steels based on measurements of the residual magnetic field (RMF) with standard tools used in the metal magnetic memory testing method. Results of the RMF measurements for samples made of two grades of austenitic steel: X15CrNi- Si20-12 and X2CrNi18-9 with a different degree of plastic strain are presented. It is found that for steel X15CrNiSi20-12 there are no changes in the RMF that can be measured using standard MMM testing method tools. In the case of steel X2CrNi18-9, the areas with plastic strain stand out in the distributions of the RMF components and their identification is possible. Quantitative relationships between the degree of plastic strain and the values of gradients are developed. Unfortunately, the degree of plastic strain can be determined unequivocally only for its large values because it is only after plastic strain exceeds 10% that the relationships become unambiguous. Consequently, the possibility of applying it in practice is substantially limited.

6

Projects management in organization on the selected example

Kania A., Spilka M., Griner S.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 56, nr 1

38--47

EN

Purpose: In this paper stages of project management taking into consideration many useful tools and methods were presented. The quality management in the project, the risk estimation, costs of the project realization and many others were discussed. The analysis of project management of an element using in an automotive industry was carried out. Design/methodology/approach: In this article classification of the projects was presented. The stages of project management and relations among them were discussed. The special attention was given for selected elements of project management in a selected enterprise. Findings: The team formation, tasks of a manager and a leader of the analyzed project were shown. The methods of quality control in the project and process of the risk management were presented. Moreover methods of time management and costs planning of the project were discussed. Research limitations/implications: Many undertakings cannot be realized without earlier plans. It is very important in case of big projects. The correct planning and a proper project management bring many advantages for organizations. Practical implications: Very often project management is separated only in a planning stage what doesn’t bring an expected effect. To prevent this it is necessary to creation of tools containing necessary conceptual, planning, implementation and control actions. Originality/value: In this paper indicated that the analyzed project was proper managed. Following stages of the project were carried out carefully. In this project many modern methods of project management were used. These methods eliminate threats which can lead to errors in the project realization.

7

Chosen aspects of project management

Kania A., Spilka M., Griner S.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 61, nr 2

388--394

EN

Purpose: In this article a problem of project management (PM) was presented. There was special attention given to objectives, scope of the project and project costs. Moreover, an analysis of project management in chosen organisation was made. Design/methodology/approach: The methodology of project management was shown. A problematic areas of project management (project quality, project risk, time and costs in a project) were discussed. Chosen stages of PM were practically checked in a selected organisation. Findings: In this paper an example of projects classification was presented. The features of project plan were proposed. The necessity of carrying out audits was presented. In the article a threats analysis and a time control were shown. Research limitations/implications: The fundamental purpose of a project management is to achieve success with a proposed budget and schedule. In this case quality, cost and time are the main parameters of the project, significant for the project realisation and evaluation of project results. Practical implications: In the paper practical directions of project planning, realisation and termination were presented. This makes possible minimization of project failures and a positive effect in a project realisation. Originality/value: The analysed PM process in the organisation allowed to know modern project management tools and techniques from a practical side. The realised project was finished with success because a working team had knowledge and experience in the project management.

8

Properties changes of Co-based amorphous alloy in thermal activation process

Spilka M., Griner S., Kania A.

Archives of Materials Science and Engineering

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2013

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Vol. 64, nr 2

118--124

EN

Purpose: The paper presents a stress relaxation process of Co69Mo2Fe4Si14B11 metallic glass and properties changes in a temperature range up to 300 ºC after annealing from 1 to 16 hours (in case of plasticity and stress relaxation researches) and 2 hours (for the magnetic properties investigations). Design/methodology/approach: The plastic properties of the studied material were determined using the bend test, applied for metallic glasses. The investigations of magnetic properties were carried out using the Ferrometer measurement system. For the higher frequencies the Remacomp C-100 system was used, allowing determination of the magnetic properties of the ferromagnetic cores. Stress relaxation investigations in metallic glasses by a bending test were carried out. Findings: The influence of thermal activation on the properties changes of Co-based metallic glass was determined after annealing from temperature of 150 to 300°C. After the heat treatment carried out the best magnetic properties were obtained for the sample annealed for 2 hours at 150°C. The increase of the magnetic field frequencies causes a significant deterioration of the material magnetic properties. High plasticity the metallic glass ribbons have to 200°C during annealing to 16 hours. Increasing the annealing temperature causes brittleness of the material. Distinct relaxation processes are observed at higher temperatures and annealing times. Research limitations/implications: Metallic glasses after heat treatment become brittle, which reduces the possibility of using these materials, and often impossible to change their geometric form. Therefore, the heat treatment of metallic glasses must be carried out after the final forming of the geometry of shaped, cores, etc., or in conditions not leading to embrittlement of the material. Practical implications: Usage of metallic glasses is possible only in a narrow range of temperatures which does not lead to significant changes of properties or after proper heat treatment carried out in the aim of specified physical properties obtaining. The important is prediction of alloy properties changes during temperature changes and material using. Originality/value: In the article influence of low-temperature thermal activation processes, which was conducted up to 16 hours, on the stress relaxation and significant changes of magnetic properties of cobalt-based metallic glass were presented.

9

Structure and properties changes of Fe78Si9B13 metallic glass by low-temperature thermal activation process

Griner S., Babilas R., Nowosielski R.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 50, nr 1

18--25

EN

Purpose: The paper presents a structural relaxation process of Fe78Si9B13 metallic glasses and structure and properties changes in a temperature range up to 300°C after annealing from 2 to 16 hours. Design/methodology/approach: The relaxation and crystallization of Fe78Si9B13 metallic glasses were examined by mechanical test, relaxation test, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. Findings: The influence of thermal activation on the structural relaxation process of Fe78Si9B13 metallic glasses was determined after annealing from temperature of 100 to 300°C. The beginning of the structural relaxation was revealed after annealing at 100 and 150°C, especially after long annealing times of 8 and 16 hours. The structural relaxation process was confirmed by examination of dimensional changes of samples associated with partial reduction of free volume and the ordering of topological and chemical structure of metallic glass. Significant changes in the structure and properties of the alloy was observed after annealing at 300°C. The reduction of tensile strength and high fragility of samples was also determined. This decrease is associated with extending of the structural relaxation and beginning of crystallization process by formation of small crystallites of α-Fe phase in amorphous matrix. Research limitations/implications: The structural relaxation process and beginning of crystallization on changes of strength, ductility, fracture morphology, structure, process of stress relaxation and geometry of studied alloy were also achieved in function of temperature and time of annealing. Practical implications: The course of relaxation processes can be used for analysis of thermal stability of metallic glasses. Originality/value: The paper presents a significant influence of low-temperature thermal activation, which was conducted up to 16 hours, on the structural relaxation and changes of selected mechanical properties.

10

Influence of thermal activation on the changes of physical properties and structure of cobalt-based metallic glass

Spilka M., Griner S., Kania A.

Archives of Materials Science and Engineering

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2012

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Vol. 56, nr 2

61--68

EN

Purpose: In this paper the analysis of influence of heat treatment on the structure and properties of AMM type (Co70.5Fe2.5Mn2Mo1Si9B15) metallic glass was shown. Moreover the discussion of the changes of tensile strength, plasticity, cracking energy, remanence, coercive force, resistivity, crystallization effect and fracture morphology of alloy in “as quenched” state and hold at the temperature range of 100-400°C for 2 hours are presented. Design/methodology/approach: Tensile test and investigation of elementary cracking energy of amorphous ribbon carried out using the testing machine were performed. Plastic properties of examined material was studied by using of transverse bend test. Investigation of magnetic properties with annular method with 50 Hz field frequency was carried out. The alloy electrical resistivity was determined with resistance bridge. Fractography investigation after tensile test was made using scanning microscope. Findings: The investigations showed that for the analysed heat treatment temperature range of 100-400°C significant changes of physical properties, fracture morphology and alloy structure are observed. Research limitations/implications: Usage of metallic glasses is possible only in a narrow range of temperatures which does not lead to significant changes of properties or after proper heat treatment carried out in the aim of specified physical properties obtaining. Practical implications: Usage of metallic glasses depending on control and regulations of alloy properties changes with proper heat treatment. It is important the prediction of alloy properties changes during temperature changes and material using. Originality/value: In the article influence of thermal activation processes on structure changes and significant changes of mechanical and magnetic properties of cobalt-based metallic glass were presented.

11

Structure, thermal and magnetic properties of (Fe72B20Si4Nb4)100-xYx(x=0.3) metallic glasses

Babilas R., Griner S., Sakiewicz P., Nowosielski R.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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Vol. 44, nr 2

140--147

EN

Purpose The work presents structure characterization, thermal and soft magnetic properties analysis of selected Fe-based metallic glasses in as-cast state and after crystallization process. Design/methodology/approach: The studies were performed on Fe72B20Si4Nb4 and Fe70B19Si4Nb4Y3 metallic glasses in form of ribbon. The amorphous structure of tested samples was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods. The crystallization behaviour of the studied alloys was examined by differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The soft magnetic properties examination of tested materials contained initial magnetic permeability and magnetic permeability relaxation measurements. Findings: The XRD and TEM investigations confirmed that the studied alloys Fe72B20Si4Nb4 and Fe70B19Si4Nb4Y3 were amorphous in as-cast state. The liquidus temperature assumed as the end temperature of the melting isotherm on the DTA reached a value of 1550 K and 1560 K for Fe72B20Si4Nb4 and Fe70B19Si4Nb4Y3 alloy, adequately. The analysis of crystallization process indicated that onset and peak crystallization temperature increased with increasing of heating rate at DSC measurements. The samples of Fe72B20Si4Nb4 alloy presented two stage crystallization process. The initial magnetic permeability of examined samples increased together with the increase of annealing temperature and reached a distinct maximum at 773 K for Fe72B20Si4Nb4 and at 723 K for Fe70B19Si4Nb4Y3 alloy. Practical implications The increasing of annealing temperature significantly improved soft magnetic properties of examined alloys by increase the initial magnetic permeability. Originality/value: The applied investigation methods are suitable to determine the changes of structure and selected properties between studied alloys, especially in aspect of the soft magnetic properties improvement after annealing process.

12

Rozwój struktury wielofazowej stali typu C-Mn-Si-Al-Nb-Ti ze wzrostem odkształcenia plastycznego na zimno

Grajcar A., Opiela M., Griner S.

Inżynieria Materiałowa

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2011

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Vol. 32, nr 1

55-61

PL

Praca dotyczy identyfikacji składników strukturalnych oraz ich cech morfologicznych w stali o strukturze wielofazowej typu C-Mn-Si-Al z mikrododatkami Nb i Ti. Próbki pobrane z odcinków blach po obróbce cieplno-plastycznej poddano jednoosiowemu rozciąganiu zgodnie z kierunkiem walcowania. Odkształcenie realizowano do wydłużenia 5, 10 i 15% oraz do zerwania próbki. Analizowano rozwój struktury wielofazowej w miarę wzrostu odkształcenia na zimno, ze szczególnym uwzględnieniem austenitu szczątkowego i martenzytu indukowanego odkształceniem. Stwierdzono, że austenit cechuje duża stabilność mechaniczna, będąca efektem dużego rozdrobnienia ziaren fazy ? w wyniku zastosowanej obróbki cieplno-plastycznej, a także postępującej stopniowo fragmentacji austenitu szczątkowego. W początkowym etapie odkształcenia przemianie ulegają duże ziarna, zlokalizowane w osnowie ferrytycznej o znacznej gęstości dyslokacji. W miarę wzrostu odkształcenia przemianie ulega austenit, stanowiący graniczne obszary wysp bainitycznych. Częściowa przemiana austenitu szczątkowego w bainicie ziarnistym oraz w środkowej części warstwowych obszarów tej fazy, ulokowanych pomiędzy płytkami ferrytu bainitycznego, rozpoczyna się przy odkształceniu około 15%. Duża stabilność austenitu występującego pomiędzy płytkami ferrytu bainitycznego wynika z ciśnienia hydrostatycznego wprowadzanego przez twarde płytki tej fazy, podobnie jak wywieranego przez indukowany odkształceniem martenzyt drobnopłytkowy. Po zerwaniu próbki stabilne pozostają rozdrobnione, warstwowe obszary austenitu oraz drobne ziarenka w bainicie ziarnistym.

EN

The work concerns the identification of structural constituents and their morphological features of C-Mn-Si-Al steel with Nb and Ti microalloying additions. The test samples taken from the sheets after the thermomechanical processing (Tab. 1) were subjected to single-axis tension along a rolling direction. Deformation was realized to elongation of 5, 10 and 15% as well as to specimens rupture. In this way, the analysis of the evolution of multiphase structure as a function of cold plastic deformation with a special attention to retained austenite and strain-induced martensite was conducted. It was found that retained austenite was high mechanically stable, retained austenite. Large grains located in a ferritic matrix of high dislocation density are transformed in an initial stage of deformation (Fig. 2, 3). As the strain increases, the retained austenite at the boundary regions of bainitic islands transforms (Fig. 2, 4). A partially transformation of retained austenite in granular bainite and in a middle part of layer regions of this phase, located between bainitic ferrite plates, begins at the strain value of about 15% (Fig. 5). The high stability of austenite occurring between bainitic ferrite plates is due to hydrostatic pressure exerting by hard plates of this phase, similarly as caused by strain-induced fine-plate martensite. After the rupture of specimens, the high mechanical stability of layer regions of austenite and fine granules in granular bainite is maintained (Fig. 6).

13

Changes of microstructure in CuNi25 alloy deformed at elevated temperature

Sakiewicz P., Nowosielski R., Griner S., Babilas R.

Archives of Materials Science and Engineering

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2011

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Vol. 50, nr 2

98-109

EN

Purpose: The aim of this paper was to present behaviour of CuNi25 alloy during elevated temperature tensile tests and describe changes of microstructure of material after deformation at the range of the Ductility Reduced Area (DRA) in which the phenomenon of Ductility Minimum Temperature (DMT) is situated. Design/methodology/approach: Numerous techniques were used to characterize properties of material: high temperature tensile tests, transmission electron microscopy (TEM), HRTEM, FFT. Findings: During the experimental studies the course of elongation and reduction of area curves has been determined. Morphology of material after deformation at elevated temperature was analysed. Research limitations/implications: Further studies should be undertaken in order to correlate effects, processes and mechanism existing and superimpose in material in range of Ductility Minimum Temperature phenomenon, it should help us understand high temperature properties of mentioned material. Practical implications: Knowledge about material properties during high temperature deformation leads to selection of the appropriate production parameters. Misapplication of parameters leads to multiplication of costs and often destruction of material during production or operating. Correct selection of technical and economical parameters of material production processes gives us supremacy in economic and technological competition. Originality/value: Investigations of this CuNi25 alloy complete knowledge about mechanical properties and help us develop correct parameters for more effective technologies for material production.

14

Structure, thermal and magnetic properties of Fe43Co14Ni14B20Si5Nb4 bulk metallic glass

Nowosielski R., Babilas R., Griner S., Czeppe T.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 38, nr 2

123-130

EN

Purpose: The paper presents structure characteristics, thermal stability and soft magnetic properties analysis of Fe-based bulk metallic glass in as-cast state and after crystallization process. Design/methodology/approach: The studies were performed on Fe43Co14Ni14B20Si5Nb4 metallic glass in a form of plates and rods. The amorphous structure of tested samples was examined by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) methods. The thermal stability of the glassy samples was measured using differential scanning calorimetry (DSC). The soft magnetic properties examination of tested material contained initial magnetic permeability and magnetic permeability relaxation measurements. Findings: The XRD and TEM investigations revealed that the studied as-cast plates and rods were amorphous. Broad diffraction halo could be observed for all tested samples, indicating the formation of a glassy phase with the diameters up to 3 mm for rods. The fracture surface of rod samples appears to consist of two different zones which might correspond with different amorphous structures of studied materials. The thermal stability parameters of rod with diameter of 3 mm, such as glass transition temperature, onset crystallization temperature and supercooled liquid area were measured by DSC to be 797 K, 854 K, 57 K, respectively. The heat treatment process of rod samples involved in crystallization of á-Fe phase and formation of iron borides at temperature above 873 K. Practical implications: The appropriate increase of annealing temperature significantly improved soft magnetic properties of examined alloy by increasing the initial magnetic permeability and decreasing the magnetic permeability relaxation. Originality/value: The success of fabrication of studied Fe-based bulk metallic glass in a form of plates and rods is important for the future progress in research and practical application of those glassy materials.

15

Influence of geometry of rapidly solidified rods on properties of Fe-Co-based alloy

Lesz S., Griner S., Nowosielski R.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 41, nr 1-2

16-25

EN

Purpose: The main aim of the paper was investigation of influence of geometry of rapid solidified rods on properties (structure, fracture morphology, microhardness) of Fe36Co36B19Si5Nb4 alloy. Design/methodology/approach: The following experimental techniques were used: differential thermal analysis (DTA), scanning electron microscopy (SEM), light microscopy (LM), X-ray diffraction (XRD) method, Vickers microhardness. Findings: Changes of mechanical properties (microhardness) and different fracture morphology of rapidly solidified rods were presented. Research limitations/implications: Obtained structures are depended on cooling rate and glass forming ability of the alloy. Practical implications: The rapidly solidified bulk alloys have been commercialized in magnetic application and high strength materials. Originality/value: Diverse fracture morphology as well as changes of microhardness in amorphous regions of differently relaxated rate are observed.

16

Influence of thermal activation on changes of mechanical properties and tensile fracture morphology surface of Ni-base metallic glasses

Griner S., Poloczek T., Nowosielski R.

Archives of Materials Science and Engineering

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2010

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Vol. 42, nr 1

13-20

EN

Purpose: The paper presents a structural relaxation and crystallization process of Ni68.7Cr6.6Fe2.65Si7.8B14C0.25 metallic glasses. The Ni68.7Cr6.6Fe2.65Si7.8B14C0.25 metallic glasses were produced by the CBMS method for two different conditions of casting at different cooling rate. Design/methodology/approach: The relaxation and crystallization of Ni68.7Cr6.6Fe2.65Si7.8B14C0.25 metallic glasses by methods: mechanical tests, scanning electron microscopy (SEM) and internal friction (IF) were studied. Findings: The investigation showed that conditions of vitrification (different, but higher than critical cooling rate) influence on different course of elementary structural relaxation processes during thermal activation. Research limitations/implications: The differences in temperature of the beginning of elementary relaxation processes and crystallization processes of alloy, in relation to strip thickness were disclosed. Practical implications: The course of relaxation processes can be used for analysis of thermal stability of metallic glasses. Originality/value: The paper presents those conditions of vitrification influence on different course structural relaxation processes during thermal activation.

17

Crystallization of Fe72B20Si4Nb4 metallic glasses ribbons

Nowosielski R., Babilas R., Griner S., Dercz G., Hanc A.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 34, nr 1

15-22

EN

Purpose: The paper presents a crystallization process of Fe-based amorphous materials. The aim of work is presentation of the influence of annealing temperature on structural changes and magnetic properties of Fe72B20Si4Nb4 metallic glasses. Design/methodology/approach: The studies were performed on metallic glasses as ribbons. Crystallization behaviour of the studied alloy was examined by differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Mössbauer spectroscopy methods. The soft magnetic properties examination of tested material contained magnetic permeability, coercive field, saturation induction and magnetic after-effects measurements. Findings: The XRD, TEM and Mössbauer spectroscopy investigations revealed that the studied alloy in as-cast state was amorphous. A two stage crystallization process was observed for studied material. The first stage of crystallization corresponding to the partial crystallization of .-Fe phase was followed by the formation of iron borides. It has shown that appropriate increasing of annealing temperature, significantly improved soft magnetic properties of examined alloy. The maximum of initial magnetic permeability is correlated with a minimum of coercive field. Practical implications: The soft magnetic properties of metallic glasses can be optimized by applying the appropriate conditions of heat treatment. Originality/value: The applied investigation methods are suitable to determine the changes of structure and the improvement of soft magnetic properties of examined Fe-based alloy in comparison with as-cast state.

18

Structure and soft magnetic properties of Fe72B20Si4Nb4 bulk metallic glasses

Nowosielski R., Babilas R., Griner S., Stokłosa Z.

Archives of Materials Science and Engineering

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2009

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Vol. 35, nr 1

13-20

EN

Purpose: The paper presents a microstructure characterization, thermal stability and soft magnetic properties analysis of Fe-based bulk amorphous materials. Design/methodology/approach: The studies were performed on Fe₇ ₂B₂ ₀Si₄Nb₄ glassy alloy in form of ribbons and rods. The amorphous structure of tested samples was examined by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) methods. The thermal properties of the glassy samples were measured using differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The magnetic properties were determined by the Maxwell-Wien bridge and VSM methods. Findings: The X-ray diffraction and transmission electron microscopy investigations have revealed that the studied as-cast bulk metallic glasses were amorphous. Broad diffraction halo can be seen for all tested samples, indicating the formation of a glassy phase with the diameters up to 2 mm. The fracture surface of rod samples appears to consist of small fracture zones, which leads to breaking of the samples into parts. A two stage crystallization process was observed for studied amorphous alloy. The changes of crystallization temperatures and magnetic properties as a function of glassy samples thickness were stated. Practical implications: The studied Fe-based alloy system has good glass-forming ability and thermal stability for casting bulk metallic glasses, which exhibit good soft magnetic properties, useful for many electric and magnetic applications. Originality/value: The obtained examination results confirm the utility of applied investigation methods in the microstructure, thermal and soft magnetic properties analysis of examined bulk amorphous alloys.

19

Structural changes of Ni-base metallic glasses during thermal activation

Poloczek T., Griner S., Nowosielski R.

Archives of Materials Science and Engineering

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2008

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Vol. 31, nr 1

33-36

EN

Purpose: The paper presents a crystallization process of i68.7Cr6.6Fe2.65Si7.8B14C0.25 metallic glasses. The Ni68.7Cr6.6Fe2.65Si7.8B14C0.25 metallic glasses was produced by the CBMS method with cooling rate corresponding for amorphous structure manufacturing. Design/methodology/approach: The crystallization of Ni68.7Cr6.6Fe2.65Si7.8B14C0.25 metallic glasses by method internal friction (IF) differential thermal analysis (DTA), X-ray and transmission electron microscopy (TEM) were studied. Findings: The investigation showed, that metallic glasses during thermal activation go through from metastable amorphous state by few medial states to the stable crystalline state (relaxation and crystallization process). Research limitations/implications: During thermal activation of metallic glasses two processes can be distinguished: structural relaxation of amorphous structure and complex crystallization process of alloy. Practical implications: Perception of structural relaxation and crystallization processes of metallic glasses can used for analysis of thermal stability of metallic glasses. Originality/value: The paper presents, that the thermal activation of metallic glasses conduct to the structural changes, which the final stage is crystalline state.

20

Shielding of electromagnetic fields by mono- and multi-layer fabrics made of metallic glasses with Fe and Co matrix

Nowosielski R., Griner S.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

45-54

EN

Purpose: In the work, influence of chemical composition, as well as magnetic and electric properties on ability of metallic glass screens for shielding of not ionizing electromagnetic fields were analyzed. Design/methodology/approach: The groups of amorphous metallic alloys with iron, iron and nickel and cobalt matrix were selected for research. Samples of afore-mentioned metallic glasses were examined from the point of view of structure, magnetic, electric and mechanical properties. Findings: There is possibility of utilization of metallic amorphous materials for screens of not ionizing, electromagnetic fields especially in range of broad-band multi-layers screens with high efficiency of shielding in wide range of frequencies. Research limitations/implications: Very good magnetic properties and parallel low electric conductivity of metallic glasses are not enough for construction of multi-layer broadband screen. Therefore for constructing broadband screen, which would attenuate much better in wider range of frequencies, we should seek solutions in multi layers systems consisting of metallic glass fabrics, layers of large conductivity materials and nonmagnetic isolating layers. Problems of determining the number of layers, individual thickness of layer, materials in relation to optimum costs of multi-layers screen metallic glasses are unsolved. Practical implications: Attenuation of metallic glass screens show very high possiblilities of metallic glasses in solution of problem of shielding electromagnetic fields. Originality/value: There are two general direction of improvement of suppression efficiency of electromagnetic fields screens: research of new constructions of elastic screens, and investigation of new materials for screens join higher magnetic properties at high conductivity. In this second area, any possibilities exist in metallic nanomaterials in form of tapes and nanocomposites consisting magnetic powders with amorphous and nanocrystalline structure.