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2. Charpy toughness and microstructure of vibrated weld metalBogdan Pučko, Vladimir Gliha, 2006, izvirni znanstveni članek Opis: Vibration during welding can be used to obtain certain changes in mechanical properties of weld metal. Research work on the influence of vibration on the secondary microstructure of welds and hence on the Charpy toughness was performed. Vibration during welding exhibits positive effects on the microstructure constituent formation. Multipass welding was simulated with reheating of the original single pass weld in order to obtain similar microstructure to multipass welds. Microstructures were examined with an optical microscope. Additionally, fractographic examination of the rupture of Charpy specimens was performed. Changes in the microstructure according to vibration were observed which affect toughness of the weld metal. Vibration during welding was rated more effective in the case of reheating the weld metal, which is the case in multipass welding. Ključne besede: welding, welded joints, mechanical properties of metals, ferrite, vibration, microstructure, toughness, notched bar testing, weld metal Objavljeno: 31.05.2012; Ogledov: 1651; Prenosov: 79
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3. Characterisation of a new dental alloy with high Au contentRebeka Rudolf, Tjaša Zupančič Hartner, Ivan Anžel, Primož Mrvar, Jože Medved, Dragoslav Stamenković, 2007, izvirni znanstveni članek Opis: The basis for developing a new dental alloy with high Au content is appropriate chemical composition and manufacturing technology. This new Au dental alloy is based on the ternary system of Au-Pt-Zn with a nominal composition of 88.5Au-8.7Pt-1.5Zn-0.5In-0.4Ir-0.3Rh. The alloy was melted and cast in a vacuum-induction melting furnace in Zlatarna Celje. Casting was followed with subsequent thermo-mechanical treatment (procedures of profile and polish milling, thermal treatment) and cutting-off strips to form a regular shape. The heat treatments of Au alloy samples were carried out in a tube furnace under different temperatures, and over different times. Testing of the new Au dental alloy included examining the initial cast, and the different heat treated conditions of the Au alloy. The optical properties of Au-dental alloy were investigated by means of spectrophotometric colourimetry. Finally the test of cytotoxicity of new Au based dental alloys using standard in vitro assays for testing the biocompatibility with establishing new, more sensitive, in vitro tests on cell lines was done.Osnovo razvoja nove dentalne zlitine z visoko vsebnostjo Au predstavljata pravilna določitev kemijske sestave in tehnologije izdelave. Nova dentalna zlitina temelji na ternarnem sistemu of Au-Pt-Zn z nominalno kemijsko sestavo 88,5Au-8,7Pt-1,5Zn-0,5In-0,4Ir-0,3Rh. Izdelava dentalne zlitine je potekala s pretaljevanjem zelo čistih komponent v vakuumski indukcijski peči v Zlatarni Celje. Temu je sledilo odlivanje taline v ustrezno formo, postopek termo-mehanske obdelave odlitka in razrez zlitine v ustrezno obliko. Toplotna obdelava je bila izvedena pri različnih temperaturah in za različne čase. Testiranje dentalne zlitine je vključevalo določitev lastnosti začetnega stanja in stanja po različnih toplotnih obdelavah. Optične lastnosti dentalne zlitine so bile raziskane s spektro-fotometrično kolorimetrijo. Na novi Au dentalni zlitini so bili narejeni še testi citotoksičnosti z uporabo standardain vitro analize za testiranje biokompatibilnosti z uvajanjem novih, bolj občutljivih in vitro testov na celični liniji. Ključne besede: dental alloy, characterisation, microstructure, properties Objavljeno: 31.05.2012; Ogledov: 1426; Prenosov: 35
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4. Composition and morphology of diborides in Al-Ti-B alloys after annealing at 1873 KFranc Zupanič, 2008, izvirni znanstveni članek Opis: In the investigation, Al-Ti-B alloys with different Ti/B ratios were annealed at 1873 K for 10 hours. Under this condition diboride particles were in contact with molten aluminium. During annealing considerable growth of remaining unmelted diboride particles took place. The composition of diboride particles shifted extremely close to the composition of pure TiB2 regardless of the Ti/B ratios in the alloys, indicating that in equilibrium almost pure TiB2 coexisted with a melt. Diboride particles were bound with well-defined crystal facets. Types and relative size of the facets depended on the Ti/B ratio. It is strongly indicated that an excess of Ti (B) in the melt over that needed to form TiB2 stabilizes crystal planes having planar arrangement of Ti (B) atoms.V tej raziskavi smo več zlitin Al-Ti-B, ki so imele različna razmerja Ti/B, žarili 10 ur pri 1873 K. V teh razmerah so bili delci diborida v kontaktu z aluminijevo talino. Med žarjenjem so diboridni delci močno zrasli. Njihova sestava se je v vseh raziskanih zlitinah močno približala sestavi čistega TiB2, kar kaže, da je v termodinamskem ravnotežju s talino praktično čisti TiB2. Diboridni delci so bili obdani s kristalnimi fasetami. Vrsta in relativna velikost faset je bila močno odvisna od razmerja Ti/B. Obstajajo trdni dokazi, da presežek Ti (B) nad vrednostjo, ki je potrebna za tvorbo TiB2, stabilizira kristalne ravnine, ki imajo ravninsko razporeditev Ti (B) atomov. Ključne besede: Al-Ti-B alloys, diboride phase, high-temperature annealing, morphology, microstructure Objavljeno: 31.05.2012; Ogledov: 1150; Prenosov: 19
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5. Metallographic sample preparation of orthodontic Ni-Ti wireLidija Zorko, Rebeka Rudolf, 2009, izvirni znanstveni članek Opis: Shape memory alloys (SMA) has been at the forefront of research for the last several decades. In this field especially, Nickel-Titanium (Ni-Ti) alloys have been found to be the most useful of all SMA. The most important applications of SMA Ni-Ti alloys are namely in medicine and dentistry, where they are used as orthodontic wires. In this paper we describe the procedure of preparing metallographic samples of typical orthodontic Ni-Ti wires which are nowadays used in dentistry praxis. We prepared the samples for microstructure observation using a light microscope. Special attention is given to the metallographic preparation, which could result in damages and deformations of the sample surfaces if the procedure is incorrect. Finally, we illustrated the typical metallographic recipe for Ni-Ti SMA alloys for optical observation. Ključne besede: shape memory alloys, Ni-Ti wire, metallographic preparation, microstructure Objavljeno: 31.05.2012; Ogledov: 1288; Prenosov: 26
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6. Microstructure of rapidly solidified Cu-Al-Ni shape memory alloy ribbonsGorazd Lojen, Ivan Anžel, Albert C. Kneissl, Elfride Unterweger, Borut Kosec, Milan Bizjak, 2005, izvirni znanstveni članek Opis: Cu-Al-Ni shape memory alloys (SMAs) are currently the only available high temperature SMAs, showing a good resistance against functional fatigue. In polycrystalline state, they are very brittle and exhibit, in general, only small reversible deformations. By melt spinning, thin Cu-Al-Ni ribbons can be manufactured directly from the melt. Appropriate casting parameters can ensurea single layer columnar structure with a fibre texture, which significantly increases the maximal reversible strain in longitudinal direction. Cu-Al-Ni ribbons, containing 13, 14 and 15 wt.% Al were cast by free jet melt spinning. Because of the alloys' low thermal conductivity, the cooling rate was surprisingly low - considering the crystal grain size - significantly below 103 K/s. Therefore, wide ribbons having a single layer columnar and (except the ribbons containing 13 wt.% Al) completely martensiticstructure could not be obtained. Regardless the chemical composition, the ribbons have a single layer columnar structure only if the thickness does not exceed approximately 50 m, otherwise the structure consists of at least two layers of equiaxed grains. In as-cast condition, only ribbons containing 13 wt.% Al seem to be completely martensitic. Heat treatments at temperatures up to 900 °C improved the structure of 13 and 14 wt.% Al ribbons. All ribbons exhibit one-way shape memory effect in as-cast condition. Heat-treated ribbons containing 13 wt.% Al exhibited two-way shape memory effect already after one bending and heating cycle. Ključne besede: metallurgy, shape memory alloys, Cu-Al-Ni alloy, microstructure, melt spinning Objavljeno: 01.06.2012; Ogledov: 1355; Prenosov: 86
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9. Quasicrystalline phase in melt-spun Al-Mn-Be ribbonsFranc Zupanič, Tonica Bončina, Alojz Križman, Werner Grogger, Christian Gspan, Boštjan Markoli, Savo Spaić, 2008, izvirni znanstveni članek Ključne besede: quasicrystals, rapid solidification, microstructure, metallography, electron emission spectroscopies Objavljeno: 01.06.2012; Ogledov: 1368; Prenosov: 73
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10. UV N2 laser ablation of a Cu-Sn-Zn-Pb alloy: microstructure and topography studied by focused ion beamFranc Zupanič, Tonica Bončina, Davor Pipić, Višnja Henč-Bartolič, 2008, izvirni znanstveni članek Ključne besede: materials investigation, microstructure, topography, copper alloys, laser, focused ion beams, UV nitrogen laser pulses, Scanning Electron Microscopy, laser ablation Objavljeno: 01.06.2012; Ogledov: 1318; Prenosov: 113
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