1. The characterization of phase transformations in rapidly solidified Al-Fe and Cu-Fe alloys through measurements of the electrical resistance and DSCMilan Bizjak, Ladislav Kosec, Borut Kosec, Ivan Anžel, 2006, izvirni znanstveni članek Opis: For the characterization of the phase transformations in the alloys during the heat treatment the various methods of the thermal analyses are available. Thermogravimetry, differential thermal analysis (DTA) and the differential scanning calorimetry (DSC) are the most frequently used methods. The phase transformations proceed in two stages, i.e. nucleation and the growth of the new phase. Both processes are closely linked with the movement of the atoms. Rapidly solidified alloys often contain the elements with the low diffusivity. During the transition from the unstable to the stable state the energy changes are small, therefore the characterization of the changes by DTA, DSC is very difficult and could not be measured. During the heat treatment the phase transformations of the rapidly solidified alloys of Al-Fe and Cu-Fe were successfully detected by the simultaneous measurements of the electrical resistance, and were compared by the DSC method. By determination of the temperature regions of the phase transitions or temperatures, where the dynamics of the changes is maximal, the samples were heat treated and analysed by the scanning and transmission electron microscopy respectively.
Ključne besede: rapidly solidified Al-Fe alloy, rapidly solidified Cu-Fe alloy, transformations, electrical resistance, differential scanning calorimetry
Objavljeno v DKUM: 03.07.2017; Ogledov: 1966; Prenosov: 149
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2. Microstructure analysis of internally oxidized Cu-C compositeRebeka Rudolf, Ladislav Kosec, Alojz Križman, Ivan Anžel, 2006, izvirni znanstveni članek Opis: On the basis of experimentally obtained data, it was established that submicron-size bubbles are formed by the internal oxidation of Cu-C composite with fine dispersed graphite particles. They are homogeneously distributed in the Cu-matrix. This process starts with the dissolution of oxygen into the metal at the free surfaces, and continues with the diffusion of oxygen atoms into the volume of copper crystal lattice where they react with the graphite particles. The reactions of dissolved oxygen with carbon yield the gas products (CO2, CO), which cannot be dissolved in the crystal lattice of the matrix. The gas molecules, which are enclosed in the space previously occupied by the graphite, have a greater specific volume than the solid graphite. Consequently, compressive stresses arise in the copper matrix around the bubbles. The interaction of these stress fields with gliding dislocations during loading could improve the mechanical properties of the copper. The internal oxidation kinetic in Cu-C composite depends on the diffusion of oxygen in the copper matrix, and the penetration depth of the internal oxidation front indicates the parabolic nature of the process.
Ključne besede: metallurgy, Cu-C composites, internal oxidation, bubbles
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3. Mechanical properties and microstructure characterisation of Au-Pt dental alloyRebeka Rudolf, Tjaša Zupančič Hartner, Ladislav Kosec, Aleksandar Todorović, Borut Kosec, Ivan Anžel, 2008, izvirni znanstveni članek Opis: Development of a dental alloy with high Au content is based on the ternary system of Au-Pt-Zn with a nominal composition of 86,9Au-9,9Pt-1,5Zn, and about 1,5 wt.% micro-alloying elements (In, Ir, Rh). The results analyses of different heat-treated states showed that the optimal mechanical properties and hardness of an Au-Pt-Zn alloy can be reached with combinations of heat treatment for 20 minutes at 723 K and then slowly cooling, if the alloy was annealed at 1223 K for 30 minutes and the water quenched. Research results confirmed that the microstructure of the Au-Pt-Zn alloy consists of two phases: α1-phase rich in Au (main phase) and α2-phase rich in Pt (minor phase). During XRD analysis and use of the Rietveld method, it was found that the α1-phase content is about 98,5 wt.% while the content of α2-phase is 1,5 wt.%. STA analyses show that the Au-Pt-Zn alloy has a solidus temperature of about 1292 K and a liquidus temperature of about 1412 K.
Ključne besede: Au dental alloy, properties, microstructure, characterization
Objavljeno v DKUM: 03.07.2017; Ogledov: 1326; Prenosov: 128
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4. Internal oxidation of silver alloys with tellurium, selenium and sulphurGorazd Kosec, Ladislav Kosec, Ivan Anžel, Vasilij Gontarev, Borut Kosec, Milan Bizjak, 2005, izvirni znanstveni članek Opis: Silver alloys with tellurium, selenium and sulphur fulfil the conditions for the internal oxidation. Microstructure of these alloys consists of matrix (dilute solid solution) and particles of intermetallic compounds. Internal oxidation of ternary alloys is very similar to that of the binary alloys, but there are also distinctions in thermodynamics properties of alloying elements.
At the direct oxidation of the particles of the intermetallic compound the phenomena of the selective oxidation was observed. Concentration of more reactive elements is increasing in the oxidized part of the particles of the intermetallic compound (Te in AgTeSe alloys). Therefore the precipitated oxides formed with diffusional internal oxidation are richer with less reactive alloying element (Se in AgTeSe alloy). In the precipitated oxide particles the concentration of selenium is more than twice higher than of tellurium.
Ključne besede: internal oxidation, silver, alloys, compound, particle
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5. Analysis of interface at explosive welded plates from low-carbon steel and titaniumBorut Kosec, Ladislav Kosec, Gabrijela Čevnik, Peter Fajfar, Mirko Gojić, Ivan Anžel, 2004, izvirni znanstveni članek Opis: On the basis of experimentally obtained data, it was established that a very thin layer of a melt is generated at the explosive welding of two metals at the bond interface within which impurities flow at the bond during melting. Rapid cooling after the collision generates an alloy of different structure and very small grains of an average thickness app. 1 to 2 micro m. The generation of such an amorphous layer in the bond area has been noticed with various metal combinations and represents a fundamental mechanism of explosive welding of metals. Using the metallographic analysis, the development of the vortices which were formed by the explosive welding of low-carbon steel and titanium plates is described in the paper.
Ključne besede: metallurgy, explosion welding, plates, composites, low-carbon steel, titanium, melt, vortex
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6. Učni načrte : gimnazija, tehniška gimnazija (140 ur)Niko Torelli, Mojca Knez, Gabrijela Dolenšek, Gorazd Lojen, Bojan Lutman, Ladislav Kosec, Bojan Bučar, 2010, slovar, enciklopedija, leksikon, priročnik, atlas, zemljevid Ključne besede: srednje šole, učni programi, vaje za srednje šole
Objavljeno v DKUM: 21.12.2015; Ogledov: 1242; Prenosov: 38
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7. Učni načrt : tehniška gimnazijaNiko Torelli, Mojca Knez, Gabrijela Dolenšek, Gorazd Lojen, Bojan Lutman, Ladislav Kosec, 2010, slovar, enciklopedija, leksikon, priročnik, atlas, zemljevid Ključne besede: srednje šole, učni programi
Objavljeno v DKUM: 21.12.2015; Ogledov: 1485; Prenosov: 23
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8. Učni načrt : gimnazija, tehniška gimnazija (70 ur)Niko Torelli, Mojca Knez, Gabrijela Dolenšek, Gorazd Lojen, Bojan Lutman, Ladislav Kosec, 2010, slovar, enciklopedija, leksikon, priročnik, atlas, zemljevid Ključne besede: srednje šole, učni programi, vaje za srednje šole
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9. Učni načrt : gimnazija, tehniška gimnazijaNiko Torelli, Mojca Knez, Gabrijela Dolenšek, Gorazd Lojen, Bojan Lutman, Ladislav Kosec, Bojan Bučar, 2010, slovar, enciklopedija, leksikon, priročnik, atlas, zemljevid Ključne besede: srednje šole, učni programi
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10. Učni načrt : gimnazija, tehniška gimnazija (210 ur)Niko Torelli, Mojca Knez, Gabrijela Dolenšek, Gorazd Lojen, Bojan Lutman, Ladislav Kosec, Bojan Bučar, 2010, slovar, enciklopedija, leksikon, priročnik, atlas, zemljevid Ključne besede: srednje šole, učni programi
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