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1

Investigations of temperature distribution in metallic glasses fabrication process

Januszka A., Nowosielski R., Pusz A.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 61, nr 2

360--366

EN

Purpose: The goal of paper is investigations of temperature distribution which is appearance during fabrication process of metallic glasses. In present work particular attention focused on system for registration of temperature distribution. Design/methodology/approach: Bulk metallic glasses in the composition as the following: Fe36Co36B19.2Si4.8Nb4 were fabricated by the die casting method. Distribution of temperature was carried out by a prototype measure system. Investigations were realized for casting process of the samples in form of rods with diameter 2, 3 and 4 mm. Temperature distributions were executed for series of samples. Moreover, investigations also enclosed structure characterization tested by X-ray diffraction and SEM. Findings: On the base of temperature distribution curves it can be observed that during casting of metallic glasses a temperature gradient have been occur. It should be note that prototype system allows to measure temperature only in cooper mould not inside of sample. Diffraction patterns confirmed that structure of tested samples was amorphous. Electron microscope observations revealed fracture morphology which is characteristic fore glassy structure. Practical implications: Analysis of temperature during casting process plays an important role in effective fabrication of metallic glasses. Cooling rate can be estimated on the base of results these analyse. Knowing the cooling rate, it could be possible to determine the glass forming ability of studied alloy. Originality/value: Investigations which have been taken in present work are novelty for the sake of optimization of casting process not only for metallic glasses, but also for nanocrystalline engineering materials.

2

Specific heat investigation of bulk metallic glasses

Januszka A.

Archives of Materials Science and Engineering

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2013

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Vol. 64, nr 2

144--151

EN

Purpose: The aim of the paper is measurements and analysis of specific heat (Cp) of bulk metallic glasses. The fabrication method and structure analysis were also described. Design/methodology/approach: The studies were carried out on FeCo-based glassy test pieces with the following composition: Fe36Co36B19.2Si4. Samples in form of rods were prepared by copper mould casting method. The structure was tested by X-ray diffraction method and scanning electron microscope observation (SEM). For determination of thermal properties the DTA and DSC method were used. Specific heat of amorphous samples was investigated by calorimetric method. Findings: The X-ray diffraction revealed that fabricated samples exhibit glassy structure. Broad diffraction halo could be seen for each tested sample. SEM observations show that fracture morphology is changed on the diameter of samples. Thermal analysis allows assigning liquidus temperature (Tl). On the base of DSC curves glass transition temperature (Tg) and crystallization temperature (Tx) were determinate. Specific heat investigation show insignificant changes in temperature range from 30 K to Tg. Practical implications: Bulk glassy FeCo-based alloys which are fabricated by rapidly solidifying technique are very interesting engineering materials because of its unique mechanical and magnetic properties. They could be used in many applications. Specific heat is important in solidification process. This property is significant input-data in computer simulation of solidification process. Originality/value: It is important to investigate thermal properties of bulk metallic glasses (including Cp) in order to understand mechanism of structural relaxation, glass transition and crystallization sequences.

3

Thermal properties of Fe-based bulk metallic glasses

Nowosielski R., Januszka A., Babilas R.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 55, nr 2

349--354

EN

Purpose: The aim of paper is presentation of results bulk metallic glasses thermal properties such as temperatures typical for glassy transition and thermal conductivity. Design/methodology/approach: Investigations were realized for Fe₃₆Co₃₆B_{19.2>/sub>Si_4.8Nb samples with dimension 3 mm in diameter. Bulk test pieces were fabricated by copper mold casting method. Thermal analysis of master alloy (DTA) and samples in as-cast state (DSC) was realized. For amorphous structure confirmation the X-ray diffraction phase analysis (XRD) was realized. Additionally scanning electron microscopy (SEM) micrographs were performed in order to structure analysis. Thermal conductivity was determined by prototype measuring station. Findings: The XRD and SEM analysis confirmed amorphous structure of samples. Broad diffraction “halo” was observed for every testing piece. Fracture morphology is smooth with many “veins” on the surface, which are characteristic for glassy state. DTA analysis confirmed eutectic chemical composition of master alloy. Thermal conductivity measurements proved that both samples have comparable thermal conductivity. Practical implications: The FeCo-based bulk metallic glasses have attracted great interest for a variety application fields for example precision machinery materials, electric applications, structural materials, sporting goods, medical devices. Thermal conductivity is useful and important property for example computer simulation of temperature distribution and glass forming ability calculation. Originality/value: The obtained results confirm the utility of applied investigation methods in the thermal and structure analysis of examined amorphous alloys. Thermal conductivity was determined using the prototype measuring station, which is original issue of the paper. In future, the measuring station will be expanded for samples with different dimensions.}

4

Structure and density of Fe36Co36B19.2Si4.8Nb4 bulk glassy alloy

Januszka A., Nowosielski R.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 52, nr 2

67--74

EN

Purpose: The work presents density measurements of bulk metallic glasses in as-cast state. Additionally casting method and structure characterization was displayed. Design/methodology/approach: The studies were performed on Fe36Co36B19.2Si4.8Nb4 metallic glasses in form of rods with diameter 2 and 3 mm. Samples were fabricated using copper mould casting method. The master alloy characteristic temperatures (Tm - melting point and T1 - liquidus temperature) were determinate by differential thermal analysis (DTA). The structure was characterized by X-ray (XRD) method and scanning electron microscope (SEM). The densities of metallic glassy rods have been measured by using the Archimedes principle. Findings: The XRD and SEM investigations revealed that the studied samples in form of rods were amorphous. Broad diffraction “halo” was observed for every testing piece. Fracture observation confirmed glassy state of samples. Archimedes principle allows calculating density of tested sample. Practical implications: The FeCo-based bulk metallic glasses have attracted great interest for a variety application fields for example electric applications, precision machinery materials or structural materials. Metallic glasses exhibit higher density than their crystalline counterparts and could be apply as a satisfactory structural material. Originality/value: The obtained results confirm the utility of applied investigation methods in the thermal and structure analysis of examined amorphous alloys. Density of metallic glasses is important properties which influence on specific application these materials. This materials offer attractive qualities, combining some of the desirable properties of conventional crystalline metals and the formability of conventional oxide glasses.

5

Thermal stability and GFA parameters of Fe-Co-based bulk metallic glasses

Nowosielski R., Januszka A.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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Vol. 48, nr 2

161--168

EN

Purpose: The paper present fabrication process, structure characterization and selected thermal properties of Fe-Co-based bulk metallic glasses in form of rods. Additionally selected GFA parameters were determined. Design/methodology/approach: The studies were realized on Fe36Co36B19.2Si4.8Nb4 metallic glasses in form of rods with diameter of 0=1.5, ø=2 and ø=3 mm. Samples were performed by the pressure die casting method. An amorphous structure was confirmed by the X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. The thermal properties of the studied samples were examined by differential scanning calorimetry (DSC). GFA parameters were calculated based on thermal properties. Findings: The X-ray analysis and scanning microscopy observation revealed that the studies as-cast rods were amorphous. For each sample broad diffraction halo could be observed. That diffraction pattern confirm formation of glassy phase in studied samples. Practical implications: Fe-Co-based bulk metallic glasses could be used in many practical application. For the sake of great mechanical, thermal and magnetic properties they may be used as a structural material and in many electric and magnetic applications (for example soft electro-magnetic cores). Knowledge about thermal properties could be useful in computer simulation of metallic glasses casting process. Originality/value: The obtained examination results allow to confirm the utility of investigation methods, which has used in this work. Thermal analysis allow to determinate selected GFA parameters for selected Fe-Co-based alloy.

6

Thermal conductivity measuring station for metallic glasses

Pusz A., Januszka A., Lesz S., Nowosielski R.

Archives of Materials Science and Engineering

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2011

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Vol. 47, nr 2

95-102

EN

Purpose: In the present paper an equipment applied in thermal conductivity measurements of metallic glasses was described. Design/methodology/approach: The paper describes the design solution of a measuring station, components, and idea of measurements of thermal conductivity. In order to correct measurement the calibration of presented equipment was realized. It was realized by determination of power losses and resistance of contacts. Methods of thermal conductivity measurements were also described in theoretical description. Findings: The suggested method of thermal conductivity measurement allows to avoid a procedure of solving complicated equations. The developed measuring station enables measurements of thermal conductivity of bulk metallic glasses in form of rod with diameter 3 mm. Research limitations/implications: The relationship between the thermal conductivity and the diameter of metallic glass samples is an interesting issue. In the future the authors are going to test rods with another diameters (not only 3 mm). Practical implications: The thermal conductivity of metallic glasses is necessary to calculate cooling rates during the fabrication of bulk metallic glasses. That are very important properties. These properties are indispensable for example in a computer simulation of a solidification process. Originality/value: Up to now there is very poor knowledge about thermal conductivity measurements of metallic glasses. There is not many references about this matter. There is no information about the thermal conductivity dependence on samples dimensions of metallic glasses.

7

Structure and properties of Fe-Cr-Mo-C bulk metallic glasses obtained by die casting method

Pilarczyk W., Nowosielski R., Januszka A.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 42, nr 1-2

80-87

EN

Purpose: The goal of this work is to investigate structure and properties of Fe54Cr16Mo12C18 alloy rods with different diameters obtained by the pressure die casting method. Design/methodology/approach: Master alloy ingot with compositions of Fe54Cr16Mo12C18 was prepared by induction melting of pure Fe, Cr, Mo, C elements in argon atmosphere. The investigated material were cast in form of rods with different diameters. Glassy and crystalline structures were examined by X-ray diffraction. The microscopic observation of the fracture morphology was carried out by the SEM with different magnification. The thermal properties of the studied alloy were examined by DTA and DSC method. Findings: These materials exhibit high glass-forming ability, excellent mechanical properties and corrosion resistance. Research limitations/implications: It is difficult to obtain a metallic glass of Fe54Cr16Mo12C18 alloy. The investigations carried out on the different samples of Fe54Cr16Mo12C18 bulk metallic alloy allowed to state that the studied ribbon was amorphous whereas rods were amorphous – crystalline. Originality/value: The formation and investigation of the casted Fe-Cr-Mo-C bulk materials and the study of glass-forming ability of this alloy.

8

Influence of nickel on structure and hardness of Fe-Co bulk metallic glasses

Nowosielski R., Januszka A.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 38, nr 1

15-23

EN

Purpose: In the present paper, influence of Ni addition on structure and hardness Fe-based bulk metallic glass were investigated. Design/methodology/approach: The studies were performed on Fe36+xCo36-x-yNiyB19.2Si4.8Nb4 ( x= 0;1, y=0;10;15) glassy alloy in a form of rods with diameter up to 5 mm. The tests, carried out to obtain amorphous metallic glasses, were realized with the use pressure die casting method. The system includes a copper mould, high frequency power supply, quartz nozzle and a source of inert gas as argon. The following experimental techniques were used for the test of structure: X-ray diffraction (XRD) phase analysis and scanning electron microscopy (SEM). Microhardness was examined by Vickers diamond testing machine. Findings: The X-ray diffraction revealed that all samples with thickness 2 mm were amorphous. The structural studies revealed that amorphous structure depended on thickness and nickel contents in a preliminary alloy. Research limitations/implications: The relationship between structure and microhardness can be useful for practical application of these alloys. Practical implications: The Fe-based bulk metallic glasses attracted great interest for a variety of application fields, for example structural materials, electric applications, precision machinery materials. These amorphous alloys exhibit high strength, a high elastic strain limit, high fracture toughness, and other useful mechanical properties which are attractive to many engineering applications. Originality/value: The originality of this paper are studies of changes of structure and hardness of Fe36+xCo36-x-yNiyB19.2Si4.8Nb4 ( x= 0;1, y=0;10;15) mainly depending on Ni addition in this alloy.

9

Glass forming ability of binary Ni60+xNb40-x (x=0;1;2) alloys

Nowosielski R., Januszka A., Pilarczyk W.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 42, nr 1-2

73-80

EN

Purpose: This paper presents the investigations results of fabrication and structure tests binary Ni-Nb metallic glasses. Design/methodology/approach: The studies were performed on Ni60+xNb40-x (x=0, 1, 2) alloys in form of ribbon and rods up to 2 mm. For the purpose of fabrication test pieces, melt spinning and pressure die casting methods were used. The main index for determine glass forming ability was thickness of specimens. To the tests of samples structure X-ray diffraction phase analysis (XRD) and scanning electron microscopy (SEM) were used. Owing to good mechanical properties of Ni-based metallic glasses, microhardness of cast rods were examined. Findings: X-ray diffraction and SEM analysis have revealed that samples in form of ribbons were amorphous, while cast rods were crystalline. Practical implications: The relationship between amorphous structure and good mechanical properties could be promising for many engineering application. The Ni-based bulk metallic glasses are newcomers engineering materials which may be applied to a new type pressure sensor exhibiting higher capability and higher sensitivity Originality/value: Paper present quite new type of binary metallic glasses based on Ni. For the sake of alloy simplicity it is possible that this alloys will be used in many applications.

10

Formation of photovoltaic modules based on polycrystalline solar cells

Dobrzański L. A., Drygała A., Januszka A.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 37, nr 2

607-616

EN

Purpose: The main aim of the paper is formation of photovoltaic modules and analysis of their main electric parameters. Design/methodology/approach: Photovoltaic modules were produced from four polycrystalline silicon solar cells, that were cut and next joined in series. Soft soldering technique and copper-tin strip were used for joining cells. Findings: In order to provide useful power for any application, the individual solar cells must be connected together to give the appropriate current and voltage levels. Taking this fact into account the analysis of photovoltaic module construction was performed. Research limitations/implications: The main goal of the research is to show the practical application of solar cells. Two photovoltaic modules were assembled and their basic electric properties were analysed. It was shown that they may be successively applied as an alternative energy source. Practical implications: Photovoltaic modules are irreplaceable in areas which are far away from power network. Simply photovoltaic module can supply small device without any problem. Originality/value: The produced photovoltaic modules and photovoltaic systems confirm the utility of solar energy in every place where the sun radiation is available. Because of exhaust conventional energy sources like coal or earth gas, new renewable sources of energy (sunlight, wind) are more and more often used. It brings huge ecological benefits.